Transformer Safety Standards

ENA DOC 18-2008 Interim Guideline for the Fire Protection of Electricity Substations

ENA DOC 18-2008 Interim Guideline for the Fire Protection of Electricity Substations

May 2008

ENA DOC 18-2008 – Interim Guideline for the Fire Protection of Electricity Substations

PREFACE This Interim Guideline discusses a number of protective measures that reduce the fire hazards and risks associated with electricity substations. Engineers involved in the design, construction, operation and maintenance of substations are offered information to assist them in the development of overall policies on f ire protection to suit their particular situations. Because the hazards and consequences of substation fires vary from one organization to another, from one location to another, and from one time to another, there is no one set of rules that can guarantee safety for all, in all places at all times. This Interim Guideline is intended to apply generally to sub-transmission, zone and distribution type substations. Reference is made to the identification and assessment of risk, the design options available to reduce these risks, the types of fire detection and fire fighting equipment available. As technological developments are continually causing changes in substations and fire protection systems, a Guideline such as this can never represent itself as a definitive work. Rather, this Guideline was prepared to fill the need for a reference on good contemporary practices, and on desirable future best practices, in the fire protection of electricity substations. The information contained should serve as a reminder of those factors that should be considered in the design and operation of substations. The Interim Guideline has been divided into thirteen (13) sections. Each section deals with a particular area of concern;

Section No. 1 deals with scope and objectives Section Nos. 2, 3, 4 and 5 deal with fires in general terms. Section No 6 deals with general building requirements Section Nos. 7 and 8 consider fires in particular types of substations. Section Nos. 9, 10 and 11 are concerned with fire control techniques Section Nos. 12 and 13 list relevant regulations and standards.

This Interim Guideline has been issued p ending a ful l review.

It sho uld b e noted th at AS 2067 – 1984 High Voltage Install ation s is als o being reviewed and t hat AS/NZS 3000 – Wirin g Rules h as recentl y been reviewed. This Guideline is intended to comp lement both of t hese Standards and to suggest ways of comply ing wit h the intentions of the Buildin g Code of Australia (BCA).

It is intended to fully review this Interim Guideline with in 12 months o f public ation.

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Energy Networks Association TABLE OF CONTENTS PREFACE ......................................................................................................................................... 1 1. SCOPE AND OBJECTIVES .............................. ........................................................... ............. 6 2. INTRODUCTION ....................................................................................................................... 7 2.1. General ............................................................................................................................. 7 2.2. Heat Energy Sources —Sources of Ignition...................................................................... 7 2.2.1. Chemical Heat Energy Sources ................................................................................ 7 2.2.2. Electrical Heat Energy Sources.......................... ....................................................... 7 2.2.3. Mechanical Heat Energy Sources ............................................................................. 7 2.2.4. Nuclear Heat Energy ................................................................................................. 8 2.3. Combustion ....................................................................................................................... 8 2.4. Explosion.............................. ............................................................................................. 8 2.4.1. General.............................. ........................................................................................ 8 2.4.2. Chemical Explosions................................................................................................. 8 2.4.3. Pressure Release Explosions ................................................................................... 9 2.4.4. Explosive Failure of Electrical Equipment ................................................................. 9 2.5. Extinguishment.................................................................................................................. 9 2.5.1. Extinguishment by Cooling........................................................................................ 9 2.5.2. Extinguishment by Oxygen Dilution................................. .......................................... 9 2.5.3. Extinguishment by Fuel Removal..................................... ......................................... 9 2.5.4. Extinguishment by Chemical Flame Inhibition................................. ........................ 10 2.6. Products of Combustion and Their Effects on Life Safety........................... .................... 10 2.6.1. General.............................. ...................................................................................... 10 2.6.2. Fire Gases............................................................................................................... 10 2.6.3. Smoke ..................................................................................................................... 10 2.6.4. Heat......................................................................................................................... 10 2.6.5. Insufficient Oxygen.................................................................................................. 10 2.7. Fire Resistance Classification ......................................................................................... 11 2.8. Fire Engineering Certification.......................................................................................... 11 3. FIRE SAFETY AND RISK MANAGEMENT ......................................................... .................... 12 3.1. Fire Safety Strategy ........................................................................................................ 12 3.2. Risk Management Approach........................................................................................... 12 4. THE RISK OF FIRE OCCURRING................................................ .......................................... 13 4.1. General ........................................................................................................................... 13 4.2. Construction Stage.......................................................................................................... 13 4.3. Site Considerations ......................................................................................................... 13 4.4. Substation Equipment and Buildings .............................................................................. 14 4.4.1. General.............................. ...................................................................................... 14 4.4.2. Oil Filled Equipment ................................................................................................ 14 4.5. Substation Operating Life................................................................................................ 14 4.6. Cables ............................................................................................................................. 14 4.7. Defective Equipment ....................................................................................................... 14 4.8. Other Causes of Fire....................................................................................................... 14 5. ASSESSMENT OF THE CONSEQUENCES OF A FIRE ........................................................ 16 5.1. Direct Effects................................................................................................................... 16 5.2. Indirect Effects ................................................................................................................ 16 5.3. Adjacent Property............................................................................................................ 16 5.4. Cost of Restoration ......................................................................................................... 16 5.5. Personnel Safety............................................................................................................. 16 6. GENERAL REQUIREMENTS FOR SUBSTATION BUILDINGS ............................................. 17 6.1. General ........................................................................................................................... 17 6.2. Permanent Buildings ....................................................................................................... 17 6.3. Prefabricated Buildings ................................................................................................... 17 7. FIRE PRECAUTIONS FOR DISTRIBUTION SUBSTATIONS................................ ................. 18

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ENA DOC 18-2008 – Interim Guideline for the Fire Protection of Electricity Substations 7.1. Pole Mounted, Kiosk and Padmounted Substations ....................................................... 18 7.1.1. General.............................. ...................................................................................... 18 7.1.2. Personnel Safety ..................................................................................................... 18 7.1.3. Siting ....................................................................................................................... 18 7.1.4. Equipment Design ................................................................................................... 18 7.1.5. Adjacent Property.................................................................................................... 18 7.1.6. Public Safety ........................................................................................................... 18 7.2. Surface Free-standing, Outdoor and Metal Enclosed Substations ................................. 18 7.2.1. General.............................. ...................................................................................... 19 7.2.2. Personnel Safety ..................................................................................................... 19 7.2.3. Building Requirements ............................................................................................ 19 7.2.4. Limitation of Damage .............................................................................................. 19 7.3. Surface Building Substation ............................................................................................ 19 7.3.1. General Comment ......................................................... .......................................... 19 7.3.2. Personnel Safety ..................................................................................................... 19 7.3.3. Building Requirements ............................................................................................ 20 7.3.4. Limitation of Damage .............................................................................................. 20 7.4. Basement, Vault or Underground Substations................................................................ 21 7.4.1. General Comment ......................................................... .......................................... 21 7.4.2. Personnel Safety ..................................................................................................... 21 7.4.3. Building Requirements ............................................................................................ 21 7.4.4. Limitation of Damage .............................................................................................. 22 7.5. High Level Substations ................................................................................................... 22 7.5.1. General Comments ....................................................... .......................................... 22 7.5.2. Personnel Safety ..................................................................................................... 22 7.5.3. Building Requirements ............................................................................................ 22 7.5.4. Limitation of Damage .............................................................................................. 23 7.6. Substation Overpressure ................................................................................................ 23 8. FIRE PRECAUTIONS FOR TRANSMISSION, BULK SUPPLY AND ZONE SUBSTATIONS . 25 8.1. General Comments .......................................................... ............................................... 25 8.2. Transformers................................................................................................................... 25 8.2.1. General.............................. ...................................................................................... 26 8.2.2. External Fires .......................................................................................................... 26 8.2.3. Internal Faults......................... ................................................................................. 26 8.2.4. Transformer Replacement....................................................................................... 26 8.2.5. Spacing........................... ......................................................................................... 26 8.2.6. Barrier Walls............................................................................................................ 27 8.2.7. Enclosed Transformers ........................................................................................... 32 8.2.8. Spilt Oil .................................................................................................................... 33 8.2.9. Cabling to Transformers .......................................................................................... 34 8.3. Outdoor HV Switchyards.................................... ............................................................. 34 8.3.1. General Comments ....................................................... .......................................... 34 8.3.2. Spacing of Equipment ............................................................................................. 35 8.3.3. Provisions for Fire Fighting................................. ..................................................... 35 8.3.4. Control Cable Trenches........................................................................................... 36 8.3.5. Housekeeping ......................................................................................................... 37 8.4. Buildings................................. ......................................................................................... 37 8.4.1. General Remarks .................................................................................................... 37 8.4.2. Buildings Adjacent to Transformers......................................................................... 38 8.4.3. Emergency Exits ..................................................................................................... 38 8.4.4. Segregation of Rooms........................... .................................................................. 38 8.4.5. Housekeeping ......................................................................................................... 38 8.4.6. Fire Detection and Alarm Systems .............................. ............................................ 38 8.4.7. Fire Fighting Systems.............................................................................................. 39 8.5. Indoor Switchgear ........................................................................................................... 39

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Energy Networks Association 8.5.1. General Remarks .................................................................................................... 39 8.5.2. Personnel Safety ..................................................................................................... 40 8.5.3. Building Requirements ............................................................................................ 40 8.6. Battery Rooms and Enclosures................................. ...................................................... 40 8.7. Control Rooms ................................................................................................................ 41 8.8. Cables ............................................................................................................................. 41 8.8.1. General.............................. ...................................................................................... 41 8.8.2. Control Cables.............................. ........................................................................... 41 8.8.3. Power Cables .......................................................................................................... 42 8.9. Hydrants and Water Storage Tanks................................................................................ 42 8.10. Portable Fire Fighting Equipment................................ .................................................... 43 8.11. Fire Break........................................................................................................................ 43 8.12. First Aid ........................................................................................................................... 44 8.12.1. Basic Equipment ..................................................................................................... 44 8.12.2. Additional Facilities which may be considered include:.......................... ................. 44 9. FIRE DETECTION AND ALARM SYSTEMS ........................................................................... 45 9.1. General ........................................................................................................................... 45 9.2. Heat Detectors ................................................................................................................ 45 9.2.1. Fixed Temperature Types ........................................................................................ 45 9.2.2. Rate of Rise Detectors ............................................................................................ 45 9.3. Smoke Detectors............................................................................................................. 46 9.4. Flame Detectors.............................................................................................................. 46 9.5. Aspirating Smoke Detectors........................ .................................................................... 46 9.6. Precautions ..................................................................................................................... 47 10. FIRE FIGHTING SYSTEMS .................................................................................................... 48 10.1. Fire Classifications .......................................................................................................... 48 10.2. Portable Fire Extinguishers............................................................................................. 48 10.3. Fire Hose Reels .............................................................................................................. 48 10.4. Fixed Fire Fighting Systems............................................................................................ 49 10.4.1. Water Based Systems ............................................................................................. 49 10.4.2. Fire Fighting Foams ................................................................................................ 49 10.4.3. Carbon Dioxide Systems......................................................................................... 51 10.4.4. Other Gaseous Systems ......................................................................................... 52 10.4.5. Dry Chemical Extinguishing Agents............................................ ............................. 52 11. ORGANISATION OF FIRE CONTROL.................................................................................... 53 11.1. Fire Control Program....................................................................................................... 53 11.2. Training ........................................................................................................................... 53 12. STATUTORY REGULATIONS .............................. ............................... .............................. ...... 54 12.1. General ........................................................................................................................... 54 12.2. Federal Regualtions (all States)...................................................................................... 54 12.2.1. Building Code of Australia (BCA) ............................................................................ 54 12.2.2. Dangerous Goods Act ............................................................................................. 54 12.2.3. AS 1940-2004 ......................................................................................................... 54 12.2.4. AS/NZS 3000 .......................................................................................................... 54 12.3. Statutory Regulations in NSW......................................................................................... 55 12.4. Statutory Regulations in Queensland................................... .............................. ............. 55 12.5. Statutory Regulations in ACT ........................................................... ............................... 55 12.6. Statutory Regulations in Victoria ......................................................... ............................ 55 12.7. Statutory Regulations in Tasmania ................................................................................. 55 12.8. Statutory Regulations in South Austalia................................ .......................................... 55 12.9. Statutory Regulations in Western Australia.......................... ........................................... 55 12.10. Statutory Regulations in Northern Territory................................................................. 55 13. SELECTED AUSTRALIAN and AMERICAN STANDARDS RELATED TO FIRE PROTECTION 56 13.1. Building Design ............................................................................................................... 56

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ENA DOC 18-2008 – Interim Guideline for the Fire Protection of Electricity Substations 13.2. 13.3. 13.4. 13.5. 13.6. 13.7. 13.8.

Detection and Suppression............................................................................................. 57 Extinguishing Equipment................................ ................................................................. 59 Maintenance.................................... ................................................................................ 59 Other Australian Standards Related to Fire Protection ................................................... 59 Emergency-Lighting-In-Buildings .................................................................................... 60 National Fire Protection Association (NFPA) Standards................................................. 60 Summary of Australian Practices .................................................................................... 61

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Energy Networks Association

1. SCOPE AND OBJ ECTIVES The overall scope of the Guideline is to be outlined including relevance to new and existing substations. Some of the objectives are;   

compliance with all relevant legislation meeting functional & performance objectives compliance with the Building Code of Australia (BCA)

The relevance of the BCA and likely method of design is to be established in the final revision.

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2. 2.1.

INTRODUCTION General

Within the framework of the safety precautions applied to electricity substations, fire protection is one of the essential features. While experience has shown that substation fires are rare, (typically 1/1000 AEP) it must be recognised that the consequences of a substation fire can be very serious. The philosophy of "Loss Control" applied to substation fires, requires an overall appreciation of the problem with conscious decisions being taken regarding the location, design and operation and maintenance of the equipment. The chemistry and physics of fire is amply covered in texts and references such as the NFPA Fire Protection Handbook. It is sufficient here to remind readers of some of the basics.

2.2.

Heat Energy Sources —Sourc es of Igniti on

Since fire prevention and extinguishment are dependent on the control of heat energy, it is important to consider the more common ways in which heat can be produced. There are four sources of heat energy: (1) Chemical (2) Electrical (3) Mechanical (4) Nuclear. 2.2.1. Chemical Heat Energy Sour ces 





Heat of Combustion - ie complete or partial oxidisation. Spontaneous .Heating - ie the process of increase in temperature of a material without drawing heat from its surroundings. Heat of Decomposition - ie heat released by the decomposition of compounds which required the addition of heat for their formation. Once decomposition has been started by heating above a critical temperature, these compounds continue to decompose with the liberation of heat.

2.2.2. Electri cal Heat Energy Sourc es 

Resistance Heating



Induction Heating



Dielectric Heating - (eg thermal runaway in bushings or cables)



Heat from Arcing – the main cause of transformer fires





Static Electricity Heating - Static arcs are ordinarily of very short duration, and do not produce sufficient heat to ignite ordinarily combustible materials such as paper. Some however, are capable of igniting flammable vapours and gases. Fuel flowing from a pipe can generate static discharges of sufficient energy to ignite a flammable vapour. Heat Generated by Lightning.

2.2.3. Mechanical Heat Energy Sour ces 

Frictional Heat - The mechanical energy used in overcoming the resistance of motion when two solids are rubbed together is known as a frictional heat. This is responsible for

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Energy Networks Association most fires caused by mechanical heating. One example is the heat caused by a slipping belt against a pulley. 



Friction Sparks - resulting from the impact of two hard surfaces. Friction sparks are formed in the following manner - heat, generated by impact or friction, initially heats the particle; then, depending on the ease of oxidisation and the heat of combustion of the metal particle, the freshly exposed surface of the particle may oxidise at the elevated temperature with the heat of oxidisation increasing the temperature of the particle until it is incandescent. Overheating of Machinery.

2.2.4. Nucl ear Heat Energ y This would not concern substation designers.

2.3.

Combustion

"Combustion" is a chemical reaction which is a combination of a fuel (reducing agent) with certain elements, prominent among which is oxygen. Combustion is always exothermic converting matter and giving off heat. Combustion can be broken up into two modes: 

The flaming type (including explosion)



The flameless surface type (including glow and deep seated glowing embers).

The flaming type is associated with relatively high burning rates. Approximately 2/3 of heat release is conducted or convected away in burning and about 1/3 is radiated away. In combustion if more heat is generated than lost to the surrounding environment the fire will grow and conversely if less heat is generated than that lost the fire will diminish. Simplifying Fires require fuel, heat and oxygen.

2.4.

Explosion

2.4.1. General The word "explosion" has assumed so many shades of meaning that it cannot be used with any degree of precision. For example, if a flammable gas-air mixture within a vessel were ignited, and the resultant pressure increase ruptured the vessel, then this would be termed an explosion. However, if the same vessel were stressed beyond its limits by steam pressure, then it could just as easily rupture and the incident would also be termed an explosion. In the widest sense, an explosion is an effect produced by the sudden violent expansion of gases and may result from: 

Chemical changes - as in the detonation of an explosive gas-air mixture.



Physical changes - such as the bursting of a boiler.

2.4.2. Chemical Explo sio ns These events may be classed as either: (a) (b)

Detonation - which is characterised by the presence of a shock wave. The pressure of a shock wave cannot be relieved by blow-out panels or rupture discs. Deflagration - where the reaction propagates through the material at a rate less than the velocity of sound.

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ENA DOC 18-2008 – Interim Guideline for the Fire Protection of Electricity Substations Generally, deflagration is the more relevant process for transformer (oil) type fires. Detonation is not generally associated with substation failures. 2.4.3. Pressur e Release Explo sio ns During normal use, boilers, gas cylinders and other pressure containers are designed to withstand expected pressures with a reasonable factor of safety. Rupture of these containers may occur due to a number of factors, such as; 

the absence, improper installation, or malfunction of a pressure release device;



some defect in the container itself;



localized heating etc.

Some items of electrical plant are enclosed in sealed compartments which can rupture violently when an internal arcing fault creates a massive build-up of pressure, cable end boxes for example. Such equipment should not be fabricated from a brittle material such as cast iron which will, upon failure, project fragments of the material at dangerous speeds. Rather, such equipment should be fabricated from sheet steel or similar materials which will tear apart instead of shattering. This will significantly reduce, but not entirely eliminate, the risk of developing projectiles during such an event. 2.4.4. Explo siv e Failure of Electri cal Equipm ent The probability of severe structural damage to substation buildings by explosion resulting from the disruption of oil-filled switchgear, cable box failure etc. is very low but incidents have occurred. In some cases, the losses have been catastrophic while in others, severe damage has been caused to associated equipment. Adequate ventilation may help to reduce the damage to the substation building by relieving the build-up of pressure following equipment failure. Some authorities provide specially designed blow-out panels for this reason. The roof and walls should be securely tied to prevent collapse of the structure under such conditions.

2.5.

Extinguishment

2.5.1. Extinguis hment by Cooling Water is the most commonly used coolant applied as a stream or a spray to remove heat from ordinary combustible materials. The extinguishing mechanism depends upon cooling the fuel and slowing the release of combustible vapours and gases. The cooling action also results in the formation of steam which tends to starve the fire of oxygen. However, the use of water may not be effective with large oil fires. 2.5.2. Extinguis hment by Oxygen Dilution Almost all fires require oxygen to allow the chemical reaction called combustion to occur. By denying a fire oxygen it is extinguished. However, this will only be effective in enclosed spaces and there may be a re-ignition risk with hot surfaces. An example of this displacement of oxygen from the environment is the use of carbon dioxide as a fire suppressant although this may introduce other hazards for the safety of personnel which will require careful management. 2.5.3. Extin gui shm ent by Fuel Removal

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Energy Networks Association Fuel removal can be accomplished literally by removing the f uel; eg by shutting off the fuel valves or by pumping the contents of a burning storage tank to another tank. 2.5.4. Extinguis hment by Chemical Flame Inhibiti on This method can only be used to fight flaming type combustion. The outstanding effect of the method is the extreme rapidity and the high relative efficiency with which flames can be extinguished. These virtues can be more fully appreciated when it is realised that this method, when properly executed, is the only means by which an explosion can be prevented in a flammable gas/air mixture after ignition has occurred. Application methods vary from the very simple to the very sophisticated which utilise highly responsive fire detection apparatus.

2.6.

Products of Combust ion and Their Effects on Lif e Safety

2.6.1. General The products of combustion can be divided into four categories: (1) fire gases, (2) flame, (3) heat, and (4) smoke. These products have a variety of physiological effects on humans, the most important being burns and the toxic effects which result from the inhalation of heated air and gases. 2.6.2. Fire Gases Most combustible materials contain carbon which burns to carbon dioxide when the air supply is ample but forms dangerous carbon monoxide when the air supply is poor. Fire gases are the major cause of fatalities in most fires. 2.6.3. Smoke Smoke is matter consisting of very fine solid particles and condensed vapour. Smoke obscures the passage of light thus restricting vision to exits and of exit signs. In many fires, smoke reaches untenable levels before temperature does. Smoke particles can be irritating when inhaled and may cause damage to the respiratory system. Smoke particles lodged in the eyes induce tears which may impair vision; when lodged in the nostrils and throat, they can cause sneezing and coughing at times when the persons so affected "need their normal faculties. 2.6.4. Heat Heat can cause physical dehydration and heat exhaustion. A person exposed to heat may die if the heat is conducted to the lungs rapidly enough to cause a serious decline in blood pressure and failure of circulation due mainly to capillary blood vessel collapse. Burns, of course, caused by contact with flame or from radiant heat will result in physical shock and possible death. High levels of radiant heat exposure can cause instant death. 2.6.5. Insuf fic ient Oxygen When the concentration of oxygen in the air drops from the normal 21% to about 15% muscular skills are diminished (anoxia). With a further reduction to between 14% and 10%, although a person will remain conscious, fatigue quickly sets in and judgment becomes faulty. In the range of 10% to 6% complete collapse occurs but revival may be effected by fresh air or oxygen. During periods of physical exertion, increased oxygen demands may result in 10

ENA DOC 18-2008 – Interim Guideline for the Fire Protection of Electricity Substations oxygen deficiency symptoms becoming apparent at higher percentages than those given above.

2.7.

Fire Resis tance Classifi cation

The fire resistance of a substation structure and its constituent material, including the substation building, is normally indicated by code letters and numbers as defined by the Building Code of Australia (BCA). The Fire-Resistance Level (FRL) assigns a Fire Rating (FR) grading period in minutes to three distinct criteria, namely;







Structural Adequacy – the ability to maintain stability and adequate load bearing capacity. Integrity – the ability to resist the passage of flames and hot gases. Insulation – the ability to maintain a temperature on the surface not exposed at below the limits specified.

The FRL requirements are expressed in the order given above with a dash indicating that there is no requirement for that criterion. For example, 120/-/- means that there is no requirement for and FRL for integrity and insulation, and -/-/- means that there is no requirement for an FRL. Internationally the code letters are designated R, E and I so that FRL 120/60/60 is equivalent to REI 120/60/60. In this Guideline, a reference to a fire resistance rating or FRL shall apply to at least the level of the “Integrity” criteria noted above. Hence, a 2 hour fire resistance requirement stated in this Guideline shall be equivalent to an FRL of 120/120/-.

2.8.

Fire Engineering Certi fic ation

Further material is to be included in the final revision

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3. FIRE SAFETY AND RISK MANAGEMENT 3.1.

Fire Safety Strategy

The overall strategy of management of fire risks is to be defined. For buildings, the following fire safety strategy may be appropriate: 

  

3.2.

Utilise fire resistant construction to contain the fire within the building, and prevent spread of fire outside the building. Utilise all building exits as the primary means of escape from the building Utilise the fire extinguishers for occupant intervention Utilise the emergency lighting and exit signage to aid occupant evacuation

Risk Management Appr oach

The Guideline will outline a risk management approach to fire in substations, including identification of all fire related risks, consequences, overall risk & mitigation strategies. Further material is to be included in the final revision

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4. THE RISK OF FIRE OCCURRING 4.1.

General

At the substation design stage full consideration should be given to the fact that fire hazard and fire risk of electrical equipment is separated into two categories, namely, fire victim and fire origin. Precautions for each category should be taken into account in the substation requirements as follows; a) Precautions for fire victim: (i) Space separation from origin of fire (ii) Flame propagation prevention; Grading Liquid containment Fire barriers Extinguishing systems    

b) Precautions for fire origin: (i) Electrical protection (ii) Thermal protection (iii) Pressure protection (iv) Fire resistant materials

4.2.

Constr ucti on Stage

The first fire risk occurs as soon as work commences on a site to develop it for a substation. During the construction stage an adequate number of portable fire extinguishers should be provided including those for fires in any temporary electrical installation and for oil or petrol fires in mobile construction vehicles. As soon as possible after construction work begins at a substation the ultimate water supply together with any hydrant installation should be commissioned so that these can be used in case of fire. For existing brownfield sites the adequacy of existing fire fighting facilities should be verified and augmented where necessary to cater for the new facilities. Burning off of any material on the site should not be permitted unless adequate safety precautions are taken and the provisions of clean air, bush fire legislation and local fire control regulations are observed. Storage and handling of flammable and combustible liquids shall comply with A.S. 1940, or relevant State regulations.

4.3.

Site Consid erations

When selecting the site for a proposed substation, consideration should be given to: 1. The possibility that a substation fire could endanger neighbouring buildings or vegetation. 2. The risk of a fire on neighbouring property damaging the substation. 3. The supply of water for fire fighting requirements (or the provision of water storage facilities). 4. The availability of Fire Brigade Services in the event of a fire. 5. The requirements of the Rural Bushfire Service (RFS), if applicable, including any Hazard Reduction Zone

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4.4.

Substation Equipment and Buil din gs

4.4.1. General In the general terms any electrical equipment containing flammable materials and not having a flameproof enclosure, and any building constructed from flammable materials is a potential fire risk. As well as being at risk the above equipment can possibly cause a fire in adjacent structures or equipment in the event of an explosion or an oil pool fire. 4.4.2. Oil Filled Equip ment The intimate contact between a heat source and combustible liquid, as exists in oil filled electrical plant, is potentially hazardous. Switching arcs, over-loading and insulation failure can all initiate a fire. However, the incidence of such fires is very low due to high quality engineering and effective mitigation measures. Despite the infrequency of such fires, their possibility must be acknowledged. The fuel content of an oil filled transformer is sufficient to create a major blaze. Consideration must also be given to the possibility of a tank rupture. Spilt oil may spread a fire beyond the immediate area and the oil may enter the public drainage system and water-ways unless suitable precautions are taken. Furthermore, burning oil may be projected beyond the immediate area and into public spaces although this is very rare. Refer to Australian Standard 1940 for definitions of Flammable and Combustible Liquids.

4.5.

Substation Operatin g Lif e

The age of the substation equipment and its loading patterns are factors which influence the equipment's vulnerability to fire. Most insulating materials deteriorate with time and with heat. The operating life and load pattern of a substation should be taken into account when a substation's fire risk is being considered.

4.6.

Cables

HV power cables are possible fire risks, especially the oil filled type. It is prudent to keep oil tanks associated with cables remote from electrical equipment. When polyvinyl-chloride insulation is involved in a fire, one of the by-products of combustion is hydrogen chloride gas. This, in turn, reacts with the water content of the air to form aqueous hydrochloric acid which is both toxic and corrosive. Sensitive relays, instruments, control apparatus, copper busbars and base metals - iron, brass, aluminium, zinc and their alloys exposed to the fumes are subject to corrosion damage. Also, in reinforced-concrete structures, chlorine contamination forms hygroscopic calcium chloride in the cement content and attacks reinforcing bars. Concrete may spall off due to the build-up of corrosion products on the reinforcing bars, months or even years after a fire. The use of low halogen and halogen-free plastic insulating materials is recommended, including non-halogenated flame retardant thermoplastic for PVC and XLPE type of plastic.

4.7.

Defectiv e Equipment


4.8.

Other Causes of Fire

Other causes of fire that need to be considered are: 

Intentionally lit fires

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

Welding in existing buildings



Vehicle fires/overheating


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5.

ASSESSMENT OF THE CONSEQUENCES OF A FIRE

Should a fire occur in a substation, the consequences can be severe. Listed below are some of the possible effects.

5.1.

Direct Effects

Equipment directly concerned in a fire will be damaged and can be put out of service for a considerable period while repairs are carried out. Frequently it is necessary to replace damaged equipment and this can result in even longer delays particularly when there is a long lead time on the delivery of equipment. In either case, disruption to the system can be considerable. For example, it may be necessary to overload other equipment to maintain supply to customers causing increased electrical losses and reduction in equipment life. It may be necessary to restrict supply to business and domestic customers and this will result in measurable losses and costs to the community. In the CBD of large cities such disruption to the system cannot generally be tolerated for significant periods of time.

5.2.

Indirect Effects

Equipment not involved in a fire may be indirectly affected by the fire by-products, smoke and heat, or by the fire fighting materials. The consequences are largely the same as in 7.1 above but usually less severe.

5.3.

Adjacent Property

A fire in a substation could subsequently involve adjacent property. This raises the issue of public safety. There is potential for court action against the Supply Authority, particularly if negligence is suspected.

5.4.

Cost of Resto ration

The cost of restoring a substation building or equipment to full working order can be considerable. Even where only a section of the substation is damaged and some equipment is still in good working order, the cost of repair can be considerably increased by the need to maintain safe working conditions for the repair while maintaining other equipment in service.

5.5.

Personnel Safety

If a fire occurs in a substation then there is a potential danger to the safety of employees working within the substation. This is particularly so when an explosion occurs and/or when flammable liquids are involved. Where a substation is close to public places, then consideration must be given to public safety. A potential danger from live electrical equipment also exists for non-skilled persons who may attempt to render assistance in the event of a fire in a substation.

16


6. GENERAL REQUIREMENTS FOR SUBSTATION BUILDINGS 6.1.

General


6.2.

Permanent Buil ding s

An outline will be provided of the structural design requirements for substation buildings including; 

Building Requirements



Design Requirements



Damage Limitation

Safety



For building requirements – several standards need to be complied with relating to collapse of structures, eg. AS 3850 – Tilt-up concrete Construction.

6.3.

Prefabri cated Bui ldi ngs

Requirements will be outlined for transportable/prefabricated substation buildings, reference AS 61330. A separate section is warranted for these buildings as existing provisions relate to permanent structures. Details will be provided of cable basements, pedestal type foundations, sealing of entry points and confined space issues.

17


7. FIRE PRECAUTIONS FOR DISTRIBUTION SUBSTATIONS 7.1.

Pole Mounted, Kio sk and Padmou nted Substations

7.1.1. General A fire in any of these types of substations will frequently involve all equipment to some extent. Therefore fire precautions are normally concerned with confining the damage to the substation or in protecting the substation from external fire sources. In terms of the requirements of the BCA, where applicable, these small facilities can be classified as Class 10a under the current effective ruling of the Australian Building Codes Board (May 2007). It is anticipated, however, that a separate and dedicated classification class that applies uniformly to all electricity infrastructure structures will become available in the future. 7.1.2. Personn el Safety For pole mounted substations the usual safety precautions for personnel working aloft should be observed. Kiosk and padmounted substations are operated from outside the enclosure, hence personnel should not be trapped by a fire in such a substation. 7.1.3. Siting Sites for these substations should be selected to minimise hazard exposure to neighbours and provide reasonable separation from adjoining fire hazards including areas of bushland. Vehicle impact is a constant danger which can be reduced by careful site selection or provision of guard rails. 7.1.4. Equip ment Design Expulsion fuses possibly represent the greatest risk of ignition and the use of "sparkless" fuse links should be considered. In kiosk and padmounted substations the use of flammable materials should be kept to a minimum. Even the so called "flame retardant" or "self extinguishing" grades of insulating materials will often burn vigorously if sufficient heat is present. Most modern kiosk and padmounted substations often contain an integrated oil containment system as part of the facility. A separate oil containment system is not usually provided for these substations. 7.1.5. Adj acent Propert y Pole mounted, kiosk and padmount or modular type substations can be classified as Class 10a buildings in relation to the BCA and its requirements for adjacent properties. In particular, the requirements of BCA Part 3.7 “Fire Safety” in respect of Class 10a facilities, should apply. 7.1.6. Publi c Safety Pole mounted, kiosk, and padmount or modular type substations should comply with the requirements of AS/NZ 3000:2000 with respect to public safety and the safety of authorised persons who may access such facilities. Choosing the appropriate measures to ensure public and authorised person safety should be based on risk assessment and mitigation to a residual negligible level. This should be in accordance with a qualitative and/or quantitative risk analysis to AS/NZS 4360:2004 ‘Risk management’, and to AS/NZS 3931:1998 ‘Risk analysis of technological systems – Application Guide’

7.2.

Surface Free-standing, Outdoor and Metal Enclosed Substations 18

ENA DOC 18-2008 – Interim Guideline for the Fire Protection of Electricity Substations 7.2.1. General In these distribution substations the transformers are usually outdoor and the switchgear is either of the outdoor type or of the indoor type provided with individual housings. Fire precautions are normally concerned with confining damage to the substation or in protecting the substation from external fire sources. 7.2.2. Personn el Safety Adequate exit facilities should be provided. Usually two (2) exits placed towards opposite ends of the substation and arranged for easy exit from normal operating positions. 7.2.3. Bui ldi ng Requi rements Either physical separation, of say 3 to 5 metres should be provided from adjacent buildings or areas where flammable materials might be stored, or a masonry wall should enclose the substation to provide effective fire segregation. Where a masonry wall is provided for fire segregation then the gates should be of a fire resistant construction. As these substations are often built on small parcels of land, or within the boundaries of an industrial complex, there is always the risk that, in time, the open space originally surrounding the substation will be lost. There are numerous examples where such space has been used to store flammable materials, to dump refuse and to extend nearby buildings. In rural or bushland settings the requirements of the Rural Fire Service should be considered to enable an adequate fire break to be maintained. Spilt oil should be contained within the substation either by bund walls, within cable pits, or by other means within the substation yard for recovery and disposal in a proper manner. Environmental requirements associated with the collection and t reatment of oil and oil contaminated water should be considered in the substation design process. 7.2.4. Lim itati on of Damage A properly graded protection system with remote back-up protection will limit the fault energy released and will substantially reduce the chance of a fire being sustained. A portable fire extinguisher of the CO 2 type should be provided close to the substation entrance - preferably outside any switchgear housings.

7.3.

Surface Bui ldi ng Substation

7.3.1. General Comm ent A fire in this type of substation will usually result in all equipment being damaged to some extent either by combustion, heat, smoke or water. Therefore, there is little point in attempting to design such substations to confine a fire to a single item of equipment, unless there are particularly onerous conditions (eg repairs or alternative supply arrangements cannot be provided within a reasonable time). Rather, the main objective is to prevent a fire within the substation from spreading to adjoining properties, or from external fires damaging the substation equipment. 7.3.2. Personn el Safety Adequate exit facilities should be provided, usually 2 doors placed towards opposite ends of the substation and arranged for easy exit from normal operating locations (eg from HV and LV. switchboards). To facilitate escape in an emergency, doors are usually arranged to open outwards. However, because substation doors often open onto a public footpath, or because the escape door may be obstructed, some authorities prefer to open them into the substation. In this case it is good practice for both doors to be kept open when the substation is occupied.

19

Energy Networks Association For security reasons it may not practical to leave both doors open in urban areas where doors open into public areas. In this case, it is more desirable to design a recessed door inside the main security fence. 7.3.3. Bui ldi ng Requi rements The substation should comply with the relevant Building Code of Australia (BCA) requirements which may include fire segregation from adjoining property by fire rated construction or physical separation. For BCA Type C construction, applicable to single and double storey construction under Class 8, the use of combustible materials is allowed and, hence, it may be necessary to ignore presence certain building elements when conducting a fire risk analysis. The performance requirements for the building structure itself may need to be considered especially where substations are located in commercial buildings and the main load resisting structure is inside the substation. In this case, the structural designer should consider the risk of a potential progressive collapse of entire structure due to fire and/or explosion. Where necessary, suitable mitigation measures should be employed including additional redundancy of key structural members. The Wiring Rules (AS/NZS 3000) calls for 2 hour fire rated enclosure of substations within buildings, for containment of spilt oil and for sealing of busbar openings. For surface building substations other standards (e.g. NFPA 850, Chapter 3) require a higher fire resistance due to the potential risk of collapse of the entire building. Where fire protection involves intumescent paint systems, consideration shall be given to its performance where an explosion may occur. In this case, a blast/abrasion may remove paint and hence the effectiveness of protection is seriously compromised.

(Figure to be revised and updated in t he Final Document to reflect curr ent practice)

A substation chamber within a customer's building will require ventilation. This is often provided in the form of louvered access doors which, due to the possibility of deflagration venting through the louvres, should generally be directed away from public areas. Fire segregation of such ventilation from other openings in external walls is covered by the Building Code of Australia. The arrangement in Figure 1 is suggested as a possible solution. 7.3.4. Lim itatio n of Damage 20

ENA DOC 18-2008 – Interim Guideline for the Fire Protection of Electricity Substations A properly graded protection system with remote back-up protection will limit the fault energy released and will substantially reduce the chance of a fire being sustained. At substations where the consequences of a fire may be particularly severe, consideration should be given to: 1. Reduction of the fuel available eg by using dry type transformers and oil-free switchgear, or 2. The installation of a fire alarm system and/or an automatic gaseous fire extinguishing system. Portable extinguishers of the carbon dioxide type should be located in readily accessible locations. Recently constructed chamber substations located in CBD areas may utilise dry type or SF 6 transformers and/or switchgear based on a risk assessment of the facility. A smoke detection and automatic fire suppression system is normally provided together with other systems designed to prevent the spread of fire. Older substations will have oil filled transformers and switchgear. A fire detection and /or extinguishing system may not have been installed.

7.4.

Basement, Vault or Undergroun d Substation s

7.4.1. General Comm ent A fire in this type of substation will usually result in all equipment being damaged to some extent either by combustion, heat, smoke or water. Therefore, there is little point in attempting to design such substations to confine a fire to a single item of equipment, unless there are particularly onerous conditions (eg repairs or alternative supply arrangements cannot be provided within a reasonable time). Rather, the main objective is to prevent a fire within the substation from spreading to adjoining properties or from external fires damaging the substation equipment. Deflagration can typically be critical for these facilities when provision for overpressure venting is limited. This has the potential for development of high compartment pressures in a deflagration incident. Any fire dampers, walls, slabs and the like must be designed to resist these higher pressures. 7.4.2. Personn el Safety Adequate exit facilities should be provided, usually two (2) doors placed towards opposite ends of the substation and arranged for easy exit from normal operating locations (eg from HV and LV switchboards). Exits should lead, through self closing fire doors, to vestibules at the foot of the access stairs or ladders. Any passage-way should lead directly to the exterior of the building. Where a CO 2 system is provided, the gas should not be injected while personnel are in the substation. With automatic gaseous systems it is mandatory to provide an audible and visual warning to personnel with a time delay before injection commences. However, a risk still remains if personnel are injured or physically incapacitated and are unable to evacuate when required. Provision may also be made for automatic systems to be deactivated while the substation is occupied. When CO 2 has been injected into a substation, the gas should be exhausted by the fire brigade before the substation is re-entered. A build up of other gases, such as ozone, may also occur as a result of an electrical fault. Adequate ventilation should be provided for the substation and suitable precautions taken when entering the enclosure following a significant electrical fault. 7.4.3. Bui ldi ng Requi rements The substation should comply with BCA requirements which include requirements for fire segregation from adjoining property and protection of structural elements of the building. 21

Energy Networks Association The performance requirements for the building structure itself may need to be considered especially where substations are located in commercial building basements and the main load resisting structure is inside the substation. In this case, the structural designer should consider the risk of a potential progressive collapse of entire structure due to fire and/or explosion. Where necessary, suitable mitigation measures should be employed including additional redundancy of key structural members. The Wiring Rules (AS/NZS 3000) calls for 2 hour fire rated enclosure of substations within buildings, for containment of spilt oil and for sealing of busbar openings. For indoor / basement substations other standards (e.g. NFPA 850, Chapter 3) require a higher fire resistance due to the potential risk of collapse of the entire building. Where fire protection involves intumescent paint systems, consideration shall be given to its performance where an explosion may occur. In this case, a blast/abrasion may remove paint and hence the effectiveness of protection is seriously compromised. Automatic fire dampers should be provided on any ducted ventilation system where the ducts enter the substation chamber. External ventilation louvres, not provided with dampers, will require protection from other openings in the face of the building as required by regulation. Wall, floor or ceiling penetrations for, busbars, cables etc., must be sealed to maintain the integrity of the fire rated construction and to prevent smoke or water from being conveyed to or from other parts of the building 7.4.4. Lim itati on of Damage A properly graded protection system with remote back-up protection will limit the fault energy released and will substantially reduce the chance of a fire being sustained. Basement, vault or sub-surface substations are difficult for the fire brigade to approach, consequently it is usually necessary to provide some means of fighting the fire remotely. Installed automatic CO2 gaseous systems are suitable. In some major cities the fire brigade have available mobile CO2 tenders. Hence, a relatively simple system of pipes and nozzles leading from a roadlevel connection point can provide an economical solution. Such installations are usually arranged to trigger dampers over the ventilation ducts in case they have not been released previously. Also, where both entrances to the substation are not visible from the injection point, it is usual to provide a warning to the fire brigade to check that personnel are not in the substation before they inject the CO2. A fire alarm system may be installed to provide early notice of a fire. Portable extinguishers of the CO2 type should be provided in the entrance vestibules. Extinguishers should be on site prior to commencement of equipping.

7.5.

High Level Substations

7.5.1. General Comm ents In high rise commercial developments it is f requently economical to develop a substation at an upper-level plant room. Special conditions apply to the fire rating, sprinklers, fire exits etc., in high rise buildings, the prime objectives being to safeguard life and to protect the structural integrity of the building in the event of a fire. Consequently, the prime fire precautions for high rise substations is to reduce flammable materials to a minimum. 7.5.2. Personn el Safety Adequate exit facilities, usually two (2) doors placed towards opposite ends of the substation and arranged for easy exit from normal operating locations. Exits should lead, through self closing fire doors, to a safe area with ready access to the building fire stairs. 7.5.3. Bui ldi ng Requi rements 22

ENA DOC 18-2008 – Interim Guideline for the Fire Protection of Electricity Substations The substation should comply with BCA requirements which include requirements for fire segregation and protection of structural elements of the building. The performance requirements for the building structure itself may need to be considered especially where substations are located in commercial buildings and the main load resisting structure is inside the substation. In this case, the structural designer should consider the risk of a potential progressive collapse of entire structure due to fire and/or explosion. Where necessary, suitable mitigation measures should be employed including additional redundancy of key structural members. The Wiring Rules (AS/NZS 3000) calls for 2 hour fire rated enclosure of substations within buildings, for containment of spilt oil (although oil filled equipment are generally prohibited in Upper Level Substations) and for sealing of busbar openings. For upper / high level substations other standards (e.g. NFPA 850, Chapter 3) require a higher fire resistance due to the potential risk of collapse of the entire building. Where fire protection involves intumescent paint systems, consideration shall be given to its performance where an explosion may occur. In this case, a blast/abrasion may remove paint and hence the effectiveness of protection is seriously compromised. Automatic fire dampers should be provided on any ducted ventilation system where the ducts enter the substation chamber. External ventilation louvres, not provided with dampers, will require protection from other openings in the face of the building as required by regulation. Wall, floor or ceiling penetrations for, busbars, cables etc., must be sealed to maintain the integrity of the fire rated construction and to prevent smoke or water from being conveyed to or from other parts of the building. There are differing opinions regarding the provision of sprinklers in high level electricity substations. On one hand the incorrect operation of a sprinkler could damage the electrical equipment and create a fault. On the other hand, the sprinklers afford the best protection for personnel and the structure of the building in the event of a serious fire. There is no clear resolution of these conflicting views. Cable risers should be sealed at each floor level by grouting or other proven fire stop system. The access doors at each level should be of fire rated construction that is equivalent to the Fire Resistance Level (FRL) of the building or that of the substation compartment, whichever is the highest. 7.5.4. Lim itati on of Damage A properly graded protection system with remote back-up protection will limit the fault energy released and will substantially reduce the chance of a fire being sustained. It is sound practice to exclude from high level substations all equipment containing insulating oil. The most popular solution is to use dry type transformers and oil free switchgear. Portable extinguishers of the CO 2 type should be provided near the entrance.

7.6.

Substation Overpressure

High voltage electrical equipment has the potential to cause overpressures under failure conditions. Where this occurs indoors there is a risk of damaging the building and any associated fir rated components. Generally, arc fault overpressures are dependent on room volume, fault level, time of the electrical fault and type of equipment. The effect of arc fault overpressures reduce as the room volume increases as the energy released is more uniform and not subject to as many variables. Oil fuelled deflagrations increase in effect with room volume increase. Peak pressures are much greater for any given volume and occur over a shorter duration, but are subject to many variables.

23

Energy Networks Association Venting for both arc fault induced overpressures and deflagrations may reduce the risk of damage to buildings and persons in the vicinity. The structural elements and fire rated components within a building should be designed to resist the potential overpressures resulting from arc fault or deflagration as appropriate Where electrical equipment is located outdoors, the risk of damage to elements other than the electrical apparatus from overpressure is minimal. The failure, however, may result in a fire and the recommended separation distances to protect against fire spread should be adopted.

24


8. FIRE PRECAUTIONS FOR TRANSMISSION, BULK SUPPLY AND ZONE SUBSTATIONS 8.1.

General Comments

This section covers the range from large transmission and bulk supply substations down to the smaller zone substations. The format adopted is to deal with general principles and recommendations which apply to all such substations then to follow on with additional comments and recommendations related to the larger or more critical installations. In terms of the requirements of the BCA, where applicable, these facilities can be classified as Class 8 under the current effective ruling of the Australian Building Codes Board (May 2007). It is anticipated, however, that a separate and dedicated classification class that applies uniformly to all electricity infrastructure structures will become available in the future. It is the responsibility of the substation Owner to assess each project on its merits and to adopt appropriate levels of fire protection measures. Distribution substations supply a relatively small load and utilize commonly available equipment in a manner which usually permits emergency restoration of supply to be achieved within a few hours after a fire. However, the loss of a large substation affects many more customers and may require weeks or months for restoration. The impact of fire on a large substation may be even more significant if the building structure has not been designed to remain functional after a catastrophic event such as overpressure and/or fire. The appropriate building design criteria to meet these special requirements are likely to exceed those of the statutory building regulations. Consequently, after factors concerning the prevention of a fire starting and personnel safety have been considered, then the focus of attention for a zone substation designer should be to minimize the effects of a fire. More explicitly, the designer should be concerned with confining the fire to one item or group of equipment; controlling the spread of smoke and restricting the damage caused by extinguishing procedures. The prevention of fires in zone and larger substations dictates that all equipment be correctly selected and installed for the duty to be performed. Fire protection measures fall into t hree (3) categories: a) Elimination – which aims at reducing or removing the cause of fires at substations. Measures such as a sound electrical protection system with appropriate back-up protection will markedly reduce the incidence of fires associated with electrical faults. Good housekeeping and maintenance will avoid many of the external fire hazards. b) Containment - which aims at restricting the damage to one item of equipment or area of the substation. Such precautions are usually passive. The use of non-flammable materials, physical spacing, segregation walls, sealing of wall and floor opening, ducts, fire retardant coatings etc. are all examples of passive systems which are dealt with in this section. With the exception of oil pool fires, fire fighting in these circumstances would normally be tackled firstly by any employees present, and later by regular fire brigade personnel. c) Extinguishment - which aims at reducing the damage to the burning equipment and to reduce (or eliminate) any fire or smoke damage to other equipment. Active systems with automatic detection and release of an extinguishing medium are usually required to achieve these objectives. The cost of installation and maintenance of such systems, plus the possibility of damage caused by the fire fighting medium must, in each case, be weighed against the risk of and potential loss resulting from a fire. Sprinkler, high velocity water spray, CO2 and foam injection systems are all examples of such active systems. They are dealt with in some detail in Section 10 of this Guideline.

8.2.

Transformers

25

Energy Networks Association 8.2.1. General Zone transformers are normally oil filled and hence they contain a large quantity of fuel. While insulating oil is a relatively safe liquid (with a flash point of about 140°C) once ignited it burns fiercely with billowing clouds of smoke and vapour. The flames can extend 10m or more above a burning transformer. 8.2.2. External Fires The great mass of a transformer provides a substantial heat sink which can absorb heat from a nearby fire for some considerable time before the surface of the oil reaches flash point. However, it is not uncommon for a bushing to crack or a gasket to fail thus permitting a flow of oil to the fire, this may then accelerate into a major conflagration. Ancillary items attached to transformers such as control equipment, cables and small pipe work are vulnerable to external fires. 8.2.3. Internal Faults An effective protection system is necessary to isolate a faulty transformer quickly in order to reduce the energy released at the fault and thereby reduce the possibility of a fire starting. Modern transformers are normally fitted with explosion vents or pressure relief diaphragms to reduce t he risk of tank rupture and a major oil spill in the event of an internal failure. However, despite these features, it is still possible to rupture the tank. Explosion vents should be directed so that discharged oil will not be sprayed over adjacent electrical plant. Preferably, the oil should be directed against a barrier wall, otherwise the oil should be directed over the transformer but, if possible, not over cable end boxes. Environmental considerations should be taken into account in the design and positioning of explosion vents in order to minimise the impacts of any discharged oil. Cable end boxes, tapchanger tanks, isolation link compartments, etc. do not have explosion vents and are more likely to rupture in the event of an internal fault. These compartments are often connected to the oil conservator thus providing a substantial source of fuel to a potential fire. 8.2.4. Transf orm er Replacement The complete destruction of a transformer by fire is always possible and in planning for such an eventuality it is necessary to consider the possibilities for transferring load, the time required to obtain and install a replacement transformer and the total cost involved. However, if the fire damage were to extend to adjoining transformers, switchgear or control buildings; then the provision of emergency supply, the time and the cost of repairs, all assume much greater dimensions. The substation designer must consider these factors and determine the appropriate trade-off for the project, between initial costs and the cost of a potential fire. In practice, several trade-offs may need to be made, especially with bund walls, blast/fire walls, acoustic/noise walls. Minimum operational requirements also need to be considered including access for maintenance and equipment access requirements for transformer removal. 8.2.5. Spacing The separation required between adjoining transformers or between transformers and other equipment or buildings is determined by consideration of: 

The heat energy radiated from a potential fire.



The vulnerability of adjacent equipment or buildings to that radiation.



The space available on the site. This will often be in conflict with the first two factors and some trade-off will be needed in most cases.

Full scale tests have demonstrated that within the vicinity of a transformer fire: 

Steel structures sagged. 26

ENA DOC 18-2008 – Interim Guideline for the Fire Protection of Electricity Substations 

Porcelain insulators cracked and lost skirts.



Cable insulation melted or burnt.



Copper fittings melted.

Observations from these tests include: 







Even where transformers have 7m clear space between them, they are not safe from fire in an adjacent transformer if the wind is from that direction. A down wind heat pattern up to 800°C can carry for say 10 metres in a moderate wind. Bushings and porcelains can be readily cracked by brief flashes of heat from 9m away. Radiation barriers (even of sheet metal) can reduce the likelihood of spreading fire from one transformer to another. However, need to also consider the duration of the fire as sheet metal barriers will collapse for other than “short” duration fires. Lattice girders and towers located above or near transformers are vulnerable to a transformer fire.

In addition, damage may occur to CT/VTs, nearby auxiliary equipment, overhead feeder conductors and gantry structures. If a gantry structure sags/fails, the overhead feeder lines/conductors may be too low outside the substation boundary and introduce new hazards to the nearby public. The attached graphs Figures 2, 3 and 4 provide some indication of the possible temperatures in the vicinity of a major transformer fire. Actual spacings adopted by various supply authorities within Australia vary widely, ranging from the minimum space required for erection and maintenance, up to 25m in some major situations. The following table indicates some typical clearances for substations using oil filled transformers without barrier walls or installed fire fighting systems.

Minimum Clearance to

Minimum Clearance to

Liqui d Volume (l)

Other TX or Non-combust ible Buildi ng Surface (m)

Combustible Building Surface (m)

1,000 < 2,000

3

7.5

2,001 < 20,000

5

10

20,001 < 45,000

10

20

45,001 < 60,000

15

30

> 60,000

23

30

Transformer

Greater separation should be considered for the lower voltage substations in locations where full scale fire brigade services are not readily available. Reduced separation may be adequate where barrier walls and/or installed automatic extinguishing systems are installed. Where bund walls are provided for oil containment, some of these separations may need to be increased and suitable provisions should be made for containment of fire fighting water. The distances for terminal yards may be insufficient for blast related damage to insulators etc. CIGRE SC A2 recommends that oil filled transformers within 50m of each other or to adjacent buildings, or to the public, be assessed for blast damage.

8.2.6. Barri er Walls Where adequate separation cannot be achieved between adjacent transformers, from buildings, or from steel structures, it is necessary to consider the erection of barrier walls that are designed 27

Energy Networks Association based on fire engineering principles including radiant heat flux levels and various flame characteristics. Barrier walls are normally of masonry construction with adequate returns or columns to provide stability. Other materials may also be used to achieve the required rating. They should be at least as high as the conservator (the UK Code specifies conservator plus 1m) or bushings.

Note - Only addresses the burning of oil on the surface of the TX tank (top and leeward). Does not consider a “pool fire” scenario where the flames can be 10 to 15m high. 28

ENA DOC 18-2008 – Interim Guideline for the Fire Protection of Electricity Substations (Figure to be revised and updated in t he Final Document to reflect curr ent practice)

29


1. Reference to “Area” could be pad or bund area. 2. Timber ignites at much lower temperatures than shown in this Figure. 3. Vertical scale should also indicate incident radiant heat levels in kW/m2 (Figure to be revised and updated in the Final Document t o reflect cu rrent practi ce)

30


Note - Timber ignites at much lower temperatures than shown in this Figure. (Figure to be revised and updated in t he Final Document to reflect cur rent practic e)

31


The performance requirements for a barrier walls are to be outlined in the final revision. Typically, several trade-offs may need to be made, especially with bund walls, blast/fire walls, acoustic/noise walls. Noise walls cannot be constructed of flammable materials. Design parameters should include - Width, Height, FRL, impact and pressure requirements [or reference a standard]. Where adequate separation cannot be achieved between a transformer and a building (eg where the switchroom wall forms part of a transformer bay): 1.

There should be no windows facing the transformer.

2.

The wall and any doors should be of a minimum two (2) hour fire rated construction. An higher fire rating may be justified depending on the outcome of a risk assessment which would consider;

3.



Likely response time of the Fire Brigade



Access / ease of extinguishing fire



Post fire performance of structure

The roof and eaves construction should be either of fire resistant construction or be shielded from radiated heat by the wall. However, a fire analysis may determine that the roof and eaves also need to be fire rated depending on the incident radiant heat flux. This will be dependant on the height of the fire and the height of the wall/roof.

Figure. 5

(Figure to be revised and updated in t he Final Document to reflect curr ent practic e) 8.2.7. Enclo sed Transf orm ers An increasing number of large transformers are being enclosed for noise suppression or as part of a multi-level substation. Transformer fires under such circumstances pose particular problems including difficult access to fight a fire, and the effects of heat and overpressure on the structural integrity of the building. Where fire rated enclosures are used, it is imperative that they have sufficient strength to resist the estimated overpressure levels (arc fault or deflagration as appropriate) in order to remain effective as fire rated elements. Open roofed noise enclosures force the fire to be attacked from above. Under these conditions foam may contain a major blaze at the top of the transformer or of spilt oil, however

32

ENA DOC 18-2008 – Interim Guideline for the Fire Protection of Electricity Substations any sheltered flames (eg below an end box) will be difficult to extinguish. Incidents have occurred where totally enclosed transformers have been completely destroyed after burning for some days because there were no means available for attacking the seat of the fire. When totally enclosing a transformer, which is not to be protected by an automatic fire installation, consideration should be given to providing pipe work to a suitable location for the fire brigade to inject foam or other media. As such a fire may burn for some time before injection is possible, the effect of temperature on the pipework, its supports and fittings must be considered. Low melting point fittings such as brass nozzles should be avoided. Where a transformer bay forms the lower part of a multi-level building the following precautions should be considered: 1.

Installation of an automatic fire fighting system (High Velocity water spray or Aqueous Film Forming Foam (AFFF).

2.

Two (2) hour minimum fire resistance rating of all structural members adjoining the transformer bay and of all walls, floor, ceiling and air ducts to the bay. A higher fire rating may be justified depending on the outcome of a risk assessment which would consider; 








3.

Design of the structural elements and fire rated components to resist the potential overpressures resulting from arc fault or deflagration as appropriate.

4.

Special drainage, with an oil interception tank and the capacity to cope with the water from the automatic system.

5.

Containment of smoke during a fire and provision for exhausting the smoke when the fire is extinguished.

8.2.8. Spilt Oil A major spillage of oil from a transformer creates the following possible problems: 

Ground fires.



Spread of fire along drains, cable chases, conduits etc.



Escalation of the fire intensity due to the greater area of oil exposed and free to burn.



Pollution due to oil escaping into gutters, roadway, storm-water drains, creeks etc.

Various laws on pollution control define the responsibility for containment and recovery of pollutants. In addition, AS 1940 also provides specific requirements for spill containment and drainage associated with transformers. If a piece of equipment contains a minor amount of oil or is located in a designated low risk area, then oil containment requirements may be reduced subject to the requirements of AS 1940. A number of solutions to the problems associated with oil spillage have been adopted by Australian Supply Authorities as indicated below.

33

Energy Networks Association 1.

Crushed gravel covering the area around transformers to a depth of 75 mm to 150 mm has been used in the past as a simple and effective solution. Pits or ditches filled with gravel may be used to increase the capacity to hold spilt oil. In the event of a substantial oil spill, prompt action may be required to prevent the oil from reaching public streets or water ways. Personnel should be t rained and contingency plans prepared to cope with a major oil spillage. Various state laws on pollution control define the responsibilities for containing pollutants.

2.

Concrete drainage aprons adjacent to the transformer base, arranged to catch any major spillage and drain it to an oil interception tank has been used by some Supply Authorities. Such drainage aprons can have a bed of large river pebbles or large crushed gravel to cool the oil before it enters the drainage system. The pebble beds will require periodic cleaning to remove accumulated dirt which could impede free drainage. If a pebble bed is not provided the drain should be provided with a flame trap. Details of a suitable flame trap and oil interception tank are shown in Figures 6 and 7 below.

3.

Bund walls surrounding a large transformer are frequently used to contain a major oil spillage. The spill containment provided by the bund walls and associated elements should comply with the requirements of AS 1940 and will generally have a capacity not less than that of the largest single unit draining to it and be equipped with an underflow discharge. Where a compound is provided with continuous gravity drainage, draining should be via a flame trap or traps to an oil spill containment facility. This will typically be an oil interception tank (Figure. 7) of sufficient capacity to retain the envisaged quantity of spilt oil. Where several bunds use a common oil interception/storage location, consideration should be given to preventing oil/water back-flowing into the adjacent unaffected transformer bunds. Where oil is to be retained within the bund area, a pipe and valve system should be provided to allow spilt oil to be drawn from the bund for treatment and/or disposal in an approved facility. Oil containment systems should include suitable provision for fire fighting water and be provided with a shut-off valve at the outlet to exclude fire fighting water when necessary. Any overflow from the oil containment system can be directed to a secondary storage area or dealt with by an emergency response process.

(This Section is to be updated in the final revision to reflect contemporary oil containment practices) 8.2.9. Cabli ng to Transf orm ers All conduits, cable trenches or tunnels in the vicinity of transformers should be sealed to reduce the risk of either burning oil or burning cable insulation from spreading the fire. Some Authorities direct bury both power and control cables within the vicinity of large transformers.

8.3.

Outdoor HV Switch yards

8.3.1. General Comm ents The provision of safety clearances and space for equipment handling in outdoor switchyards goes a long way towards providing adequate separation to prevent a fire from spreading to other equipment. Additional consideration should, however, be given to:

34




Transformer locations and separation (see Clause 8.2)



The possible violent failure of VT's, CT's etc.



The location of gantry structures



Overhead lines / feeder conductors



Access for fire fighting



Control of spilt oil



Possible propagation of fire along cable trenches



Good housekeeping

8.3.2. Spacin g of Equip ment Clause 8.2 provides information on transformer fires including some estimates of temperatures associated with major transformer fires. The effects of such temperatures on nearby equipment should be considered. Special consideration should be given to equipment that is especially costly or difficult to repair such as circuit breakers or 132kV cable terminations. 8.3.3. Provisions for Fire Fighting The switchyard layout should provide a reasonable approach for the fire brigade, preferably from two (2) directions for larger substations. Water supply should be checked and a hydrant provided at the perimeter of the yard if existing hydrants in public roads are inadequate or not sufficiently close. Where no town water is available, consideration should be given to the installation of a water storage tank (see Clause 8.9). Portable extinguishers should be provided in a location readily accessible but protected from the weather. Secure weather protected storage should be provided for portable extinguishers and any other fire protection equipment or materials kept on site. The location of the storage room or kiosk should permit ready access during a f ire.

35


(Figures to be revised and updated in the Final Document t o reflect curr ent practice for various oil containment options) 8.3.4. Contr ol Cable Trench es Control cable trenches should be covered, provided with fire stops at critical locations and arranged to drain spilt oil back towards its source. In the vicinity of large transformers, some authorities prefer 36

ENA DOC 18-2008 – Interim Guideline for the Fire Protection of Electricity Substations to obtain greater fire protection of control cables by direct burial of cables or use of buried ducts, or by providing a layer of gravel over the cable chase as shown below (Figure 8).

(Figure to be revised and updated in t he Final Document to reflect cur rent practic e)

8.3.5. Housekeeping Switchyards should be kept free from accumulated rubbish, weed growth, etc., drains should be kept clear and flammable materials should not be stored in switchyards or on transformer roadways.

8.4.

Buildings

8.4.1. General Remarks Buildings should comply with the Building Code of Australia (BCA) requirements. The fire protection section of BCA adopts the general approach of prescribing requirements on the following criteria: (a)

The USE to which the building is put (ie the "Class" of Building)

(b)

The HEIGHT of the building above ground (ie the "rise in storeys")

(c)

The LOCATION of the building (ie whether inside or outside a designated "fire zone")

Fire zones are established by local authorities and generally relate to areas of sizeable commercial or business development. It is usual for a higher degree of inbuilt fire protection to be required in such zones. The BCA requirements also incorporate the concepts of a "fire source feature" and an "effective distance". A "fire source feature" represents a theoretical burning building emitting heat radiation. Major factors involved with the spread of fire are the intensity of heat radiation, the geometrical relationship and the distance apart of buildings. The "effective distance" between a fire-source f eature and a proposed new building determines what precautions are required to guard against the spread of fire and the undue heating of structural members by radiation. The BCA does not address the specific problems of electricity substations. However, the broad principles are applicable and local authorities are likely to press for the most stringent interpretation for substations in highly developed locations.

37

Energy Networks Association Substation buildings can be deemed as Class 8 buildings if they are not pole mounted, kiosk, padmount or modular type substations and should comply with the BCA, Section C generally and, in particular, clause C2.13 “Electricity Supply System”. 8.4.2. Build ings Adjacent to Transformers Where buildings are not adequately spaced from transformers and barrier walls have not been constructed, then the following precautions are recommended: There should be no windows facing the transformer The wall and any doors should be a minimum two (2) hour fire rated construction. A higher fire rating may be justified depending on the outcome of a risk assessment which would consider; 








The roof and eaves construction should be either of fire resistant construction or be shielded from radiated heat by the wall (see Figure 5). However, a fire analysis may determine that the roof and eaves also need to be fire rated depending on the incident radiant heat f lux. This will be dependant on the height of the fire and the height of the wall/roof. 8.4.3. Emergency Exits Each switchroom, cable basement etc. should be arranged to provide safe exit for personnel should any item of plant fail violently, or ignite. This would usually be achieved by providing two (2) exits towards opposite ends of each room. The disabling effects of smoke and fumes should be considered. The provision of adequate ventilation and illuminated EXIT signs and emergency lighting can help under such circumstances. 8.4.4. Segregation of Rooms The extent of fire segregation within a substation building will depend largely on: 

The size of the building



The importance of the substation to the network or the consequences of a major fire



The type of equipment housed

In general, larger substations will be divided into a number of separate rooms which can fairly easily be fire-segregated by the use of appropriate building methods. It should be remembered that roof spaces should also be segregated to control the spread of fire or the collapse of the roof onto otherwise undamaged equipment. Cable basements should be segregated from switch and control rooms. All cable penetrations of walls or floors should be sealed to prevent the spread of fire, smoke and corrosive fumes liberated by burning PVC. The fire stop should be at least 100 mm thick. 8.4.5. Housekeeping Good housekeeping is an important factor in preventing fires. Particularly during equipping stages, all rubbish, off-cuts of insulation etc. should be regularly cleaned-up. Flammable materials such as oil, jointing compound, cleaning fluids, paint etc., should be stored in a safe manner preferably remote from electrical plant. 8.4.6. Fire Detect ion and Alarm Systems 38

ENA DOC 18-2008 – Interim Guideline for the Fire Protection of Electricity Substations The objective of a fire detection and alarm system is to provide early notice of a f ire so that prompt action may be instigated to minimize the damage. Fire alarm systems are now generally installed at zone substations and also in larger bulk supply and transmission substations. The coverage provided may be limited to special hazard areas (control panels, switchrooms, cable basements etc.) or may cover the whole substation building. The application of detection and alarm systems to outdoor substation equipment is quite rare. The considerations which may lead to their installation in any type of substation would include: 

BCA regulation (eg if substation is combined with another building which requires alarms).



Particular hazards (eg at an industrial site).





Remoteness (ie where there are no neighbours to raise the alarm or where alarms would avoid an undue delay in attendance of a fire brigade). Supply reliability (ie where the consequences of a substation fire would justify the cost of installation and maintenance of an alarm system).

Fire alarm signals, where provided, are normally sent direct to the System Control Room and need to be separated from other substation alarms so that fire brigade and electrical operation staff can be alerted at the same time. Alternatively, a parallel alarm can be provided direct to the fire brigade. Details of various types of detection and alarm systems are given in Section 9 of this Guideline. 8.4.7. Fire Fight ing Systems As with detection and alarm systems, fixed fire fighting systems are only installed in selected locations, in determining if a system should be installed, similar considerations would apply, plus: 

the consequences of a fire spreading from unit to unit, or its effect on the building.



the lack of adequate access to fight a fire with mobile equipment.

Details of various types of fire fighting systems are given in Section 10 of this Guideline.

8.5.

Indoor Switch gear

8.5.1. General Remarks The degree of a hazard represented by indoor switchgear will vary significantly depending on a number of factors including:

The interrupting system

e.g. bulk oil, minimum oil, air break, vacuum, SF 6.

The form of switchgear

metal clad, metal enclosed, open.

The fault duty

maximum current.

The protection systems

maximum clearing time, I 2T.

The busbar system

compound filled, air insulated, gas insulated, the degree of segregation

Cable terminations

compound filled, air insulated.

These matters relate primarily to the proper selection and use of equipment. The precautions which may be taken in the design of switchrooms to mitigate the effects of fire relate to the layout and construction methods used.

39

Energy Networks Association 8.5.2. Personn el Safety Adequate exit facilities should be provided, usually two (2) doors placed towards opposite ends of the switchroom. Attention is drawn AS 2067 High Voltage Installations (refers to IEC document 61936-1:2002) which deals with Personnel Safety aspects of electrical installations including metal clad switchgear. 8.5.3. Bui ldi ng Requi rements After complying with the requirements of the BCA it will be necessary to consider any further desirable precautions. Supply Authorities tend to take more fire precautions when using bulk oil circuit breakers than with other types of switchgear. These precautions include: Fire resistance construction of the switchroom. 



Automatically closing fire doors to other rooms.



Possibly the segregation of large switchboards into several rooms.









Either no windows or the use of wired glass in metal frames (to avoid the danger of flying glass in the event of an explosion). Sealing of cable penetrations through the switchroom floor to prevent spilt burning oil from entering the cable basement and to prevent smoke from a cable fire entering the switchroom. Some authorities provide pressure relief venting to minimise damage to the building in the event of an explosion. In some critical locations gaseous systems are installed.

Where switchgear other than the bulk oil type is installed, concern is more related t o end box, busbar and similar failures rather than the possibility of an oil fire.

8.6.

Battery Rooms and Enclosu res

Hydrogen produced when wet cell batteries are recharged can give rise to the risk of an explosion if it is allowed to accumulate sufficiently. Alternative battery types evolve far less hydrogen and therefore present a much smaller risk. Dispersing the hydrogen by providing effective ventilation throughout the room is an essential precaution. Hydrogen is lighter than air and will tend to concentrate at ceiling level so that ventilation must be provided in the ceiling or high up on the outside walls. Unventilated structural pockets in the ceiling should be avoided. The AS/NZS Wiring Rules (AS/NZS 3000) require that a battery shall be installed only in a room or enclosure which is adequately ventilated. Where ventilation is required it should be provided through high and low vents. The BCA “Deemed to Satisfy” provisions require that batteries must be separated from the remainder of the building with construction that has a fire rating of not less than 2 hours. However, the BCA also allows for “Alternative Solutions” for battery accommodation provided that compliance with the “Performance Requirements” can be demonstrated. Other relevant Australian Standards, including AS 2676.2 and AS 3011.2, do not mandate the provision of separate battery rooms for substation batteries. The critical concentration of hydrogen in air which will create an explosive mixture lies between the range of 4% to 75%. To be safe it is necessary to limit the concentration of hydrogen in a battery room to a maximum of 2%. The process of water electrolysis in a fully charged lead-acid, nickeliron, or nickel-cadmium battery will evolve a volume of 0.43 m 3 hydrogen per cell for every 1000 Ah of charging current. The maximum charging current should be considered. Under ideal conditions of ventilation the rate of air intake to prevent the concentration of hydrogen going above 2% would be at least 50 times the rate of hydrogen evolution. Pockets of slow moving air will be unavoidable and for this reason a safety factor of 4 for enclosures and 10 for battery rooms is advisable. Thus for complete safety the rate of air intake should be from 200 times the rate of hydrogen evolution for enclosures and 500 times for battery rooms.

40

ENA DOC 18-2008 – Interim Guideline for the Fire Protection of Electricity Substations In rooms containing large banks of batteries, the provision of natural ventilation would require very large openings. Forced ventilation with a flameproof fan should be considered for such installations and should comply with AS 1668 and AS 1076. Smoking should be prohibited inside battery rooms. Provided adequate ventilation exists at all times a battery room will not be a "hazardous location" as defined by AS/NZS 3000 - Wiring Rules. For mechanically ventilated battery rooms the possibility of fan failure must be considered and, accordingly flameproof light and power fittings should be installed. It is prudent for such items as links, fuses, light and power switches or other equipment which can cause an electric arc to be excluded from battery rooms.

8.7.

Contro l Rooms

The minimum fire requirements for a control room are that it should be readily accessible in an emergency and that it be segregated from any major fire risk area. Many authorities provide fire resistant construction and self closing fire doors to control rooms. Control cable routes should be sealed. Additional fire protection in control rooms may be justified to ensure people cannot be trapped inside. Most utilities require that staff call their operational centres from this location and hence, in a fire, people will be in this room momentarily. Suitable measures may include fire rated segregation from adjacent rooms and / or provision of a direct exterior exit. For larger or more critical substations, consideration may be given to providing fire alarms in control rooms or within control panels and cabling areas. It is usual for these installations to employ very early smoke detection aspirated systems sensitive to smoke from overheated insulation so that an incipient fire may be controlled early in its life. It should be remembered that smoke from PVC, and other common insulating plastics, is very corrosive and can cause considerable damage to control equipment. Some major installations are provided with automatic fire fighting systems in control rooms. Usually they will be “Inergen” gas systems which may discharge directly into control panels or cabling areas; or the whole room may be flooded with gas. Dual detection systems are often provided to guard against incorrect operation and manual over-ride facilities are available. Any forced ventilation or air conditioning system should be shut down when a fire is detected to reduce the spread of smoke. Smoke exhaust facilities may also be provided. Smoke from bush fires has been known to activate such systems incorrectly.

8.8.

Cables

8.8.1. General To reduce the impact of potential fires, the use of low halogen and halogen-free plastic insulating materials is recommended, including non-halogenated flame retardant thermoplastic for PVC and XLPE type of plastic. Further material will be included in the final revision including a discussion on the use of cable coating as appropriate to reduce fire propagation risk. 8.8.2. Contr ol Cables It is common practice to use PVC insulated and sheathed control cables in substations. As mentioned elsewhere, burning PVC liberates a large volume of smoke which: is toxic 



obscures vision and,



is highly corrosive to both metal and concrete.

Where a substantial number of such cables are congregated on supporting trays or at floor or wall penetrations there is always the risk of fire. The precautions usually taken to minimize this risk are: (i)

to ensure that cables are properly rated and not overloaded 41

Energy Networks Association (ii) to avoid undue congestion (iii) to seal all penetrations of walls or floors (iv) to maintain good housekeeping. Further precautions which may be warranted in larger or more vital substations include: (v)

the use of low-smoke or flame retardant type PVC These materials have additives to improve their fire performance under specified test conditions. The tests vary considerably and the actual improvement in practical applications may be only marginal. Such cables cost approximately 10% more than conventional PVC/PVC

(vi) the use of alternative insulating materials such as EPR*. These materials have substantially better fire resistant properties than PVC However they are much bulkier, are sensitive to transformer oil, are only available in limited colours and cost approximately twice the price of conventional PVC/PVC cables. (*EPR = Ethylene Propylene Rubber, low smoke, toxicity and acid vapour grade). Teflon and similar materials are tough, chemically insensitive and suitable for reasonably high temperature operation. (vii) spacing of cable trays, say 450 to 600 mm apart, the segregation of control from power cables and the use of enclosed trays can all reduce the fire hazard, (viii) the application of commercially available, inert, flame retardant coating products which may be brushed or sprayed onto existing cables. (ix) the installation of an automatic sprinkler or gaseous system. 8.8.3. Power Cables The basic fire precautions to be taken in all high voltage cable installations are: (i)

to avoid undue congestion

(ii)

to space and support cables properly - particularly where they cross one another

(iii) to apply fire retardant coating within the building (iv) to provide physical protection around any cable joints if necessary. Further precautions which may be required in critical locations or at large substations include: 







the application of non-absorbent fire resistant tapes to cables the provision of separate chases for important circuits (eg 132kV or higher voltage cables, bustie or transformer cables crossing outgoing feeder cables). These chases should be covered or be filled with sand. higher voltage (132kV and above) cable sealing ends should be separated as far as possible to reduce the chance of fragments from a faulted unit from damaging a sealing end which may take weeks to repair. Alternatively, barriers or walls can be used to provide suitable protection. Note that the use of fibreglass reinforced polymeric sealing ends will significantly reduce the risk of fragments. the provision of an automatic extinguishing system.

Consideration needs to be given to the flame propagation rates of vertical cables and groups of cables.

8.9.

Hydrants and Water Storage Tanks

Early in the design of a substation the location of local fire hydrants should be determined and the pressure and flow rates ascertained. For zone substations, the presence of a hydrant within say 50 meters of the substation may suffice. However, if there is any doubt about the adequacy or accessibility of the public hydrant, the mains should be extended to a hydrant on the site located close to the main entrance. Larger bulk supply and transmission substations should have a network 42

ENA DOC 18-2008 – Interim Guideline for the Fire Protection of Electricity Substations of hydrants strategically placed so that two hydrants may be used on each transformer. Hydrants should be outside any safety enclosures and in cold climates should be protected from freezing. Where no mains water supply is available, or where the flow rate may drop below 15 litre/sec, during excess demand periods, then water storage should be provided. At zone substations a 14,000 litre tank should be adequate for the generation of foam. It should be arranged to facilitate use by the fire brigade either by their suction hose or by providing pipework and a coupling which matches their hose fittings. Domestic services should be taken off above mid height to ensure that a reasonable quantity of water is available for an emergency. Large bulk supply and transmission substations will require greater storage and special consideration should be given to storage requirements for automatic high velocity water spray or foam systems. In this regard foam systems require very much less water than high velocity water spray systems. If it is intended that water be used from a tank supply independently of the fire brigade, then a suitable pump would be required.

8.10. Portable Fire Fighti ng Equipm ent All zone and larger substations should be equipped with a suitable range of portable fire extinguishers and other fire fighting equipment. The following list is intended as a guide to the equipment that may be provided. 1.

Zone Substati ons up to 132kV



30 litre mobile AFFF extinguisher



9 litre AFFF extinguisher



5 kg CO2 extinguishers in each control and switchroom. Ad di ti onal equi pm ent as r equir ed b y s it e lo cat io n:



Hydrant and/or Fire Hose Reel



Water Storage (14 000 litre) and pump if necessary



10 x 20 litre drums of AFFF solution if remote from major fire brigade, to provide additional foam making capacity as the supplies carried by a fire appliance may be inadequate for a large oil fire.

2.

Bulk Supply and Transmiss ion Substations



30 litre mobile AFFF extinguisher



9 litre AFFF extinguishers with recharges



5 kg CO2 extinguishers in equipment rooms



Hydrants to serve each transformer bay



Canvas hose; standard, diffuser and foam branch pipes with spanners etc.



10 to 20 x 20 litre drums of AFFF solution. Ad di ti onal eq ui pm ent , depend in g o n s it e co nd it io ns :



Water storage (28 000 litres plus any requirement for high velocity water systems) and pump if required.

8.11. Fire Break Where there is danger of damage from bush fires due to burning grass or trees, a fire break at least 5 m wide should be provided around the substation site. The exact width would be governed by site conditions and the requirements of the local Rural Bushfire Services (RFS). Precautions should also be taken to prevent burning materials being drawn into buildings by fans or air conditioning units.

43


8.12. First Aid 8.12.1. Basic Equi pment Adequate first aid equipment should be available at all large substations, either as a permanent fixture or carried by all work teams. A first aid kit should contain the following items: 

Lint



Cotton Wool



Bandages



Wound dressings



Burn dressings



Mild antiseptic fluid



Eye drops



Salvolatile



Bi-carbonate of soda

Scissors



Tweezers



Splinter probe



8.12.2. Addit ional Facilities wh ich may be consi dered include: (i)

A stretcher

(ii)

Personnel eye wash and shower facilities to quickly douse burning clothing. These should be installed and located close to locations where employees may be sprayed with burning or corrosive liquid. A reliable water supply is required.

(iii) Water-Jel fire blankets, are designed to smother the flames of a person on fire and reduce shock. A blanket is simply wrapped around the victim. The blankets are of specially woven wool fully immersed in a gel and supplied in sealed unit containers. The gel as well as assisting in extinguishing any fire also cools the burn victim, and acts as a dressing. A water-jel blanket container should be located adjacent to the perceived risk area. They require periodic inspection and replacement.

44


9. FIRE DETECTION AND AL ARM SYSTEMS 9.1.

General

For the design, installation and commissioning of automatic fire alarm systems, refer to Australian Standard AS 1670-2004. Signalling back to the System Control Room needs to be separated from other substation alarms so that both the fire brigade and electrical operator can be alerted at the same time. Substation buildings can be deemed as Class 8 buildings if they are not pole mounted, kiosk, padmount, or modular type substations and should comply with the BCA, Part E2 ‘Smoke Hazard Management’ generally and, in particular, with clause E2.2 and E2.3 regarding airhandling, smoke detection and alarm, and special hazards of substation fire risk. There are various types of detectors and their designs vary with the manufacturer, but they fall into the following general types:

9.2.

Heat Detector s

Heat detectors depend for their action on heat from the fire. Heat detecting devices fall into two general categories: — (i)

Those that respond when the sensing elements reach a predetermined temperature, ie fixed temperature (static) elements (9.2.1).

(ii)

Those that respond to an increase in temperature at a rate greater than some predetermined value ie rate-of-rise temperature elements (9.2.2.).

Heat detectors generally provide slower response to smouldering or common smoke generating electrical fires. Thermal detectors provide lower false alarm rate than smoke detectors and provide a benefit where the environment is not suitable for smoke detectors. 9.2.1. Fixed Temperatur e Typ es 









Bi-metal Strip - a bi-metal strip bends to close a set of contacts when the predetermined operating temperature is reached. Bi-metal Disc - At normal ambient temperatures the disc is concave but when the predetermined operating temperature is reached the disc snaps over to a convex shape and closes a set of contacts. Fusible Link - a link which normally holds an alarm switch in the open position but when the design temperature is reached the link melts thus closing the switch. Thermostatic Cable - A two core cable whose core insulation is heat sensitive. When the design temperature is reached the insulation melts causing the cores to touch thus completing an initiating circuit. Quartoid Bulb - When the temperature surrounding the bulb reaches the predetermined level the bulb fractures, releasing the internal pressure thus commencing the fire control.

9.2.2. Rate of Rise Detector s Pneumatic Tubing - In this system a length of tubing passes through the area to be protected. Any expansion of air in the tubing escapes through a small vent. If the tubing is heated at an abnormally high rate insufficient air escapes through the vent and a diaphragm is expanded thus triggering the alarm circuit.

45

Energy Networks Association Thermo-Couple - Two sets of thermocouples are mounted in a common housing, one set is exposed to the area to be protected while the other is shielded. A fire will produce a voltage in the circuit due to the difference in temperature of the thermocouple junctions. This voltage initiates an alarm circuit. Line Detector - A four core cable having two cores of high thermal resistivity and two cores of low thermal resistivity. One core of each type is exposed to any heat in the vicinity of the cable more than its mate. By suitable connection in a bridge circuit, the difference in resistance of the pairs is detected and when this reaches a prescribed amount an alarm circuit is closed.

9.3.

Smoke Detector s

There are essentially two basic types of smoke detectors: Ionization Point Type Detectors - These detect very small particles which are invisible to the naked eye. A radio-active source is used to ionize the air in a chamber. A current flows between two electrodes in the chamber. When smoke enters the chamber it reduces the current flow which is sensed and initiates an alarm. Photo-Optical Point Type Detectors - These detect larger smoke particles by either obscuring the path of a light beam, or by deflecting a light beam into a photoelectric cell. The photo optical smoke detectors detect visible particles of combustion and operate on a light scattering principle. The detectors have a symmetrical lens and a protective cover that allows ready entry of smoke while providing high immunity to air movement and dust accumulation. Photo optical detectors measure the density of smoke particles in the 0.01 to 10 micron range and provide an active output proportional to the amount of smoke present in the chamber. They are responsive to both visible and invisible products of combustion with response to fires in the incipient stage. The detector continuously samples the air in the area and signals an alarm when the smoke density in the area exceeds the threshold and automatically resets itself when the smoke falls below the threshold.

9.4.

Flame Detector s

A flame detector determines the presence of a fire by the appearance of radiant energy. There are three basic types of flame detectors and a further combination type: 1.

Ultraviolet - This device has a sensing element responsive to radiant energy in the ultraviolet range. These detectors may be activated by switching arcs.

2.

Photoelectric - Utilises a photoelectric cell which either changes its electrical conductivity or produces a voltage when exposed to radiant energy.

3.

Flame Flicker Infra-Red - Uses a photoelectric cell and produces an output voltage when the observed light is modulated at the frequency characteristic of the flicker of a flame.

4.

Ultraviolet / Infra-Red - These detectors contain two sensors and give an alarm only when both ultraviolet and infra-red are detected. This eliminates many of the causes of false alarms.

9.5.

Aspi rating Smoke Detector s

Aspirating smoke detection systems differ from point type smoke detectors in that they operate in the high to very high sensitivity range. Aspirating systems are designed to detect a slowly developing fire where there is perhaps minimal smoke.

46

ENA DOC 18-2008 – Interim Guideline for the Fire Protection of Electricity Substations Aspirating type smoke smoke detectors continually continually draw air air into a piping network network attached attached to the detector unit where the air is passed passed through a filter to remove any dust. dust. The air sample then passes through a laser chamber where the light scatter caused by any smoke contained in the air is measured, processed and the results compared to a reference level. In an aspirating type system the sampling pipework is the only part that needs to be on the ceiling or in the area to be monitored, the equipment requiring requiring maintenance is mounted at eye level on the wall. The main advantage of an aspirating type smoke detection system is that the detector unit can be located remote from the area being monitored and can be located outside the fire zone. The ability to locate the detector unit unit remote from the area being monitored monitored is an advantage in electrically hazardous hazardous areas inside substations because of the need to gain access to the detector unit for servicing and maintenance thus avoiding the need to arrange for de-energisation of equipment. However, However, deactivation of aspiration type smoke detection systems in a work area is normally required to avoid spurious alarms. The sensitivity of the aspirating type smoke detector system can be adjusted as required for reliable performance without triggering nuisance false alarms.

9.6.

Precautions

When selecting fire detectors for a substation alarm system, care should be taken to ensure that the detectors are compatible compatible with the proposed installation. installation. For example, if the substation rooms could experience rapid rises in temperatures then the “Rate of Rise” detectors may cause problems.

47


10. FIRE FIGHTING SYSTEMS 10.1 10.1.. Fire Classifi cation s Substation buildings buildings can be deemed Class 8 buildings if they are not pole mounted, kiosk, padmount, padmount, or modular type substations and should comply with the BCA, Part E1 ‘Fire Fighting Equipment’ regarding substation substation fire risk. Fires are classified as per Australian Standard AS 2444-2001 as follows: Class "A": Fires involve carbonaceous carbonaceous solids, which generally have a vegetable origin. Class "B": Fires involve flammable liquids. Class "C": Fires involve flammable gases. Specialist advice should be sought for this t ype of risk. Class "D": Fires involving combustible metals. These should not be applicable to substations. Class “E”: Fires involving energized electrical equipment. Where a fire including an electrical hazard can be anticipated, anticipated, the extinguishment extinguishment must be electrically non-conductive in addition to having the relevant classification. classification. The marking of 'E' on the fire extinguisher extinguisher indicates the agent as discharged is electrically non-conductive. non-conductive.

10.2 10.2.. Portable Fire Exting uish ers The following table lists the types of portable fire extinguishers available available and the classes of fire for which they are intended. They must be used only in the classes of fire so designated.

Type of Extinguisher

Class of Fire A Solids

Au st ral ian Standards

Colour of Container

Supplementary Colour

B Liquids

Water (Soda Acid)

X

AS1841.2-1997

Red

Water (Gas Container)

X

AS1841.2-1997

Red

Water (Stored Pressure)

X

AS1841.2-1997

Red

Foam (Chemical)

X

X

AS1841.4-1997

Blue

Foam (Gas Container)

X

X

AS1841.4-1997

Blue

Foam (Stored Pressure)

X

X

AS1841.4-1997

Blue

Dry Chemical

X

X E*

AS1841.5-1997

Red

White

Carbon Dioxide

X

X E*

AS1841.6-1997

Red

Black

For installation and maintenance procedures for portable fire extinguishers refer Australian Standards AS 1851-2005 and AS 2444-2001. *The letter 'E' on an extinguisher indicates that the agent as discharged is electrically nonconductive.

10.3. Fire Fir e Hose Hos e Reels Fire hose reels consisting of a length of 25 mm diameter rubber hose coiled onto a metal reel is an effective appliance for initial containment of Class "A" fires. The hose is permanently connected to the water service and the "shut off" type nozzle is clamped into the stop valve

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ENA DOC 18-2008 – Interim Guideline for the Fire Protection of Electricity Substations mechanism such that the stop valve must be open before the nozzle is released. Fire hose reels should not be used on liquid or electrical fires.

10.4 10.4.. Fixed Fire Fighti ng Systems Systems The following fixed types of fixed fire fighting systems are commercially available. 10.4.1. Water Based Systems As a general statement statement water should should not be used on on live electrical equipment. equipment. Water Water extinguishes a fire mainly by cooling the point where combustion is taking place. Also, when water is converted from liquid to vapour its volume at ordinary pressure increases about 1700 times. This large volume of steam displaces an equal volume of air (oxygen) surrounding surrounding a fire thus reducing the oxygen available to sustain combustion. combustion. 10.4.1.1. 10.4.1.1.

Water Water Sprin kler kl er - Refer AS 2118-2 2118-2006 006

There are several types of water sprinkler systems which may be classified as follows: Wet Pipe Systems - These systems employ automatic sprinklers attached to a piping system containing water under pressure at all times. When a fire is detected individual sprinklers are actuated by the heat, and water flows through these sprinklers immediately. Dry Pipe Systems - In these systems automatic sprinklers are attached to piping which contains air or nitrogen under pressure. When a sprinkler is opened by the heat f rom a fire, the pressure is reduced. A "dry pipe valve" is opened by water pressure, and water flows out of any opened sprinkler. Pre-action Systems - A variation variation on the dry pipe system in which the air in the piping may or may not be under pressure. When a fire occurs, a supplementary fire detecting device in the protected area is actuated; this opens a valve which permits water to flow into the piping system and be discharged by any of the automatic sprinklers that have been opened by the heat of the fire. Deluge System - These systems are similar to pre-action systems, except that all sprinklers are open at all times. When heat from the fire actuates the fire detecting device, water flows too and is discharged from all the sprinklers on the piping system, thus "deluging" the protected areas. 10.4.1.2. 10.4.1.2.

High Veloc Veloc it y Wafer Wafer Spray Syst em (Refer NFPA NFPA 15)

High velocity water spray systems are frequently used to extinguish fires involving oil or similar flammable liquids. The systems usually involve heat actuated detectors operating an automatic mechanical flooding flooding valve to supply water to deluge projectors arranged both over and around the unit being protected. The projectors are designed to provide an expanding cone of fine but broken streams of water, with high velocity and momentum, evenly distributed over the area covered by the projector. In addition to the normal extinguishing action of water on a fire, the impact of water in this form onto an oil surface creates an emulsion which will not burn. It is essential that the water supply to a high velocity system have an adequate pressure and flow-rate. While the mains supply may suffice in some cases, most installations are provided with an automatic pump. 10.4. 10.4.2. 2. Fire Figh tin g Foams 10.4.2.1. 10.4.2.1.

General Remarks

Foams should not be used to fight fires in live electrical equipment. equipment. Fire fighting foam is a mass of gas-filled bubbles formed by various methods from aqueous solutions of especially formulated foaming agents. Since foam is lighter than the aqueous solutions from which it is 49

Energy Networks Association formed and lighter than flammable liquids, it floats on all flammable or combustible liquids, producing an air-excluding, cooling, continuous layer of vapour sealing, water bearing material for purposes of halting or preventing combustion. Fire fighting foams are formulated in several ways, some are thick and viscous forming tough heat-resistant blankets over burning liquid surfaces and vertical areas. Some foams are thinner and spread more rapidly, some are capable of producing a vapour-sealing film of surface-active water solution on liquid surfaces. Some are meant to be used as large volumes of wet gas cells for inundating surfaces and filling cavities. Foam breaks down and vapourises its water content under attack by heat and flame. It therefore must be applied to a burning surface in sufficient volume and rate to compensate for this loss, and to provide an additional amount to guarantee a residual foam layer over the hot surface. Certain chemical vapours or fluids may quickly destroy foam and t urbulent air or violently uprising combustion gases from fires may divert light foam from the burning area. 10.4.2.2.

Protein Foaming Agents

Protein type foam concentrates are available for proportioning to a final concentration of from 3% to 6% using fresh or sea water. In general these concentrates produce dense, viscous foams of high stability and high heat resistance. They are non-toxic and biodegradable after dilution. They are suitable for use in ambient temperatures from -7°C t o 49°C. They have a limited shelf life and old stocks should be replaced on a routine basis. 10.4.2.3.

Aqu eous Film Formi ng Foam: (AFFF)

These are synthetically produced materials that form air foams similar to those produced by the protein-based materials. In addition these foaming agents are capable of forming water solution films on the surface of flammable liquids. AFFF concentrates are available for proportioning to a final concentration from 3% to 6% by volume using either fresh or sea water. AFFF foam would generally be more effective for substation fires than protein foam. The air foams generated from AFFF solutions possess low viscosity, have fast spreading and levelling characteristics, and act as surface barriers to exclude air and halt fuel vapourisation just as other foams do. These foams also develop a continuous aqueous layer of solution under the foam with surface activity which maintains a floating film on hydrocarbon fuel surface to help suppress combustible vapours and cool the fuel substrate. This film which can also spread over fuel surfaces not fully covered by foam is self healing following mechanical disruption and continues as long as there remains a reservoir of nearby foam for its production. However, to ensure fire extinction an AFFF blanket, as with other types of foam, should entirely cover the fuel surface. AFFF is non-toxicc and biodegradable after dilution. It has a long shelf life. AFFF foam is widely used by fire brigades, however only a limited stock is carried on each vehicle. Consideration should be given to storing a quantity of AFFF foam at substations remote from a major fire station, 10 to 20 drums (20 litre) should be adequate for most substations. 10.4.2.4.

High Expansio n Foam

High expansion foam is used to control and extinguish fires involving ordinary combustibles (wood, paper, etc.) and flammable liquids and is particularly suitable as a flooding agent when the supply of water in relatively large volumes is a problem. Foams of expansion from 100 to 1 up to 1000 to 1 can be generated. High expansion foam is excellent for the displacement of vapour, heat and smoke from an area. It is particularly suited for indoor fires but its use outdoors may be limited because of the effects of weather. Automatic injection system should be switched out of service while personnel are in the protected zone, since visibility, breathing and movement are all severely hampered in the foam.

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ENA DOC 18-2008 – Interim Guideline for the Fire Protection of Electricity Substations 10.4.2.5.

Fixed Foam Installati ons

Fixed installations with pipework and detectors similar to sprinkler systems, but with f oam storage and mixing facilities, are commercially available. AFFF foam is particularly suitable requiring only a relatively low pressure and quantity of water. The long shelf life of the foam concentrate and the simple mixing equipment allow for an economical installation with low maintenance costs. 10.4.3. Carbo n Dio xid e Systems 10.4.3.1. General Carbon dioxide gas is non-combustible and does not react with most substances. As a gas it can penetrate and spread to all parts of a fire, it will not conduct electricity and can therefore be used on energized electrical equipment. It is about 11/2 times as heavy as air. Although carbon dioxide is only mildly toxic, it can produce unconsciousness and death when present in fire extinguishing concentrations. The action in this case is more related to suffocation than to any toxic effect of the carbon dioxide itself. A concentration of 9% is about the maximum the average human can withstand without losing consciousness within a few minutes. A higher concentration could bring about helplessness almost immediately. In most small enclosures protected by CO 2 any person present when the discharge starts would probably have little difficulty escaping before a critical concentration is reached. However, the cloud produced by the CO 2gas may obscure vision and panic or obstacles could prevent a successful escape. Accordingly, alarms are fitted to automatic systems to alert personnel prior to the release of CO 2. 10.4.3.2.

Limitation s as an Extinguis hing Agent

Because CO2 may not cool hot surfaces below their ignition point, fires apparently extinguished by CO 2 may reignite after the smothering atmosphere has dispersed. In such cases it may be necessary to reduce the oxygen content to about 6% and to maintain this concentration long enough for the embers and hot surfaces to cool to below the ignition temperature of the fuel. Often, long periods of time are required for sufficient cooling. 10.4.3.3.

Carbon Dioxi de Gas Installati ons

The area to be protected is fitted with open nozzles connected by pipework to either storage tank(s) or to a remote cartoon dioxide injection point. When detectors in the protected area sense the presence of a fire, a sequence of events is initiated with appropriate time delays: 

An alarm notifies the fire control centre that the detectors have operated and also alerts personnel in the protected area that it is about to be flooded with carbon dioxide.



The ventilation is turned off.



Fire dampers and doors are closed.



Where the carbon dioxide is stored in tank(s) on site then the control valve is opened either automatically or manually and the protected area is flooded with carbon dioxide. Where only an injection point is provided then it is necessary to bring a carbon dioxide tanker to site and connect it to the injection point.

A carbon dioxide system may be used in the following situations: (i)

Where a clean extinguishing agent is considered important.

(ii)

For the protection of electrical equipment.

(iii) For flammable liquids or solids. (iv) To protect equipment of high value. 51

Energy Networks Association 10.4.4. Other Gaseous Systems Further material will be included in the final revision regarding Argonite (Gaseous system) and Pyrogen systems (oxygen starving system)

10.4.5. Dry Chemical Extinguishing Agents Dry chemical is a powder mixture which is used as a fire extinguishing agent. It is suitable for fighting fires involving flammable liquids and live electrical equipment. The ingredients used in dry chemical are non-toxic. However, the discharge of large quantities may cause temporary breathing difficulty and may seriously interfere with visibility.

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11. ORGANISATION OF FIRE CONTROL 11.1. Fire Contro l Program Every Electricity Authority should have a Fire Control Program. The Program should include: 

Regular inspection of substations to ensure that correct fire control practices and good housekeeping are maintained. This also applies during the construction of the substation.



Maintenance of a register of all fire fighting equipment.



Testing and servicing of all fire fighting equipment.



Regular testing of all fire alarms.







Liaison with local fire brigade and bushfire groups, with particular reference to the electrical hazards in substations. Established procedures with local fire brigade officers for an electrical operator to be in attendance before they enter a live substation or commence to fight a substation fire. Training of Authorities' personnel in fire fighting procedures. Refer to 11.2 below.

Depending upon the size of the Electricity Authority, the Fire Control Program may only require a part time appointment or may have several staff to carry out the above duties.

11.2. Training The Fire Control Program should ensure that all appropriate employees are trained in the following: 

Correct use of portable extinguishers for various classes of fires.



Special precautions to be taken with electrical fires.



Procedures to be taken in the event of a fire.



First aid to fire associated injuries.



Handling of fixed fire fighting appliances.

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12. STATUTORY REGULATIONS 12.1. General In each state there exists a network of State, Federal and Local Regulations, by-laws etc. which control various aspects of buildings and fire protection. These regulations are dynamic and they differ from State to State. The following list indicates the range of statutory regulations that are applicable at the time of writing and which have a direct impact on substation design with regard to fire protection. It is the designer's responsibility to determine which regulation applies to a particular project.

12.2. Federal Regualti ons (all States) 12.2.1. Bui ldi ng Code of A ust ralia (BCA) Produced and updated by the Australian Building Codes Board (ABCB). Contains a uniform set of technical provisions for the design and construction of buildings and other structures throughout Australia.

12.2.2. Dangerous Goods Act Administered by the Dept. of Industrial Relations. This act uses AS 1940 - Rules For The Storage And Handling Of Flammable and Combustible Liquids as its guide. The act governs such matters as the control of electrical equipment and its proximity to the above liquids. 12.2.3. AS 1940-2004 Rules for the storage and handling of flammable and combu stibl e liquids (known as the SAA Flammable and Combust ible Liq uids Code). Provides rules for the planning, design and construction, and safe operation of all installations in which flammable or combustible liquids are stored or handled. In separate sections it deals with minor storage, package storage and handling, storage in tanks, fuel dispensing, piping and tank auxiliaries, heating of liquids, operations and fire protection facilities. Appendices deal with tank venting and combustion characteristics, and show a typical work permit. 12.2.4. AS/NZS 3000 Rules for the electrical equipment of bui ldings , structu res and premises. Part 1 - 2000 Wiring methods (known as the SAA Wiring Rules). Establish the requirements for ensuring safety from fire and shock for all electrical installations in or on buildings, structures, and premises, other than for installations in a supply authority's premises, and for equipment installed in a consumer's premises and belonging to a supply authority. Sections deal with definitions and nomenclature; general requirements; general arrangements, control and protection; installation of wiring; installation of equipment; earthling; special situations; extra-low voltage installations; high voltage installations; and hazardous locations. Appendices provide additional data, and include an introduction to Part 2 of the rules. Included with the Rules is Supplement No. 1, Cable and Conductor Tables - Imperial Units which reproduces the essential requirements of Appendix B of superseded AS CC1, Part 1 - 1969, for the purpose of providing ratings of imperial cables. For Notes see Doc. 3000N.

54


12.3. Statut ory Regulation s in NSW (Request that State jurisdictions supply current details for inclusion in the final Revision) .

12.4. Statut ory Regulation s in Queensl and (Request that State jurisdictions supply current details for inclusion in the final Revision)

12.5. Statut ory Regulation s in ACT (Request that State jurisdictions supply current details for inclusion in the final Revision)

12.6. Statut ory Regulati ons in Victori a (Request that State jurisdictions supply current details for inclusion in the final Revision)

12.7. Statut ory Regul ations in Tasmania (Request that State jurisdictions supply current details for inclusion in the final Revision)

12.8. Statut ory Regulation s in South Austalia (Request that State jurisdictions supply current details for inclusion in the final Revision)

12.9. Statut ory Regulation s in Western Aust ralia (Request that State jurisdictions supply current details for inclusion in the final Revision) Worksafe (2004) Code of Practice - Tilt-up construction Fire collapse requirements Department of Consumer and Employment Protection

12.10. Statut ory Regul ations in Northern Territ ory (Request that State jurisdictions supply current details for inclusion in the final Revision)

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13. SELECTED AUSTRALIAN and AMERICAN STANDARDS RELATED TO FIRE PROTECTION 13.1.

Bui ldi ng Desig n

AS 1530 Methods for Fire Tests on Building Materials Components and Structures Part 1 - 1994 Combustibility test for materials. Describes a combustibility test for classifying building material, either coated or uncoated. Apparatus, test procedures and classification criteria are given. Part 2 - 1993 Test for Flammability of materials (Incorporating Corrig.) Describes procedure for preparing and determining flammability index of thin sheet or woven materials of pliable nature which are combustible and do not melt readily or shrink away from an igniting flame. The index is determined according to a speed factor, heat factor. See also A30. Part 3 - 1999 Test for early fire hazard properties of materials. Describes a test .for graded building material on the basis of ignition tendency, heat development, flame spread and tendency to produce smoke. Apparatus, test procedure and indexes for grading are given. Part 4 - 1975 Fire-resistance test of structures. Describes a fire-resistance test for grading elements of building structures. Apparatus, test procedures and methods of grading are given. AS 1668 Rules for the use of mechanical ventilation and air conditioning in buildings (Known as the SAA Mechanical Ventilation and Air Conditioning Code) Part 1 - 1998 Fire precautions in buildings with air-handing systems. Applies to the design, construction, installation and operation of air-handling systems, in relation to preventing the spread of fire through a building by way of the air-handling system. Mandatory safety requirements, intended for incorporation by reference in building regulations and the like, are specified. AS 1682 - 1990 Fire dampers Deals with materials, design and manufacture, rating, testing and marking requirements for fire dampers of rectangular and circular face of single and multiblade construction. An appendix provides information on installation. AS 1890 - 1999 Thermally-released links. Applies to links for general fire protection services in buildings but not to links incorporated in sprinkler heads. It provides for identification, construction requirements and performance requirements in terms of strength, operating temperature, operation, corrosion resistance and coating tests. An appendix deals with the fatigue test for links for use in high temperature industrial environments. AS 1905 Rules for the construction and installation of fire resistant doors, fire windows and fire shutters (known as the SAA Fire Door Code) Part 1 - 2005 Fire-Resistant Doorsets. Gives basic design data (except method of construction) for fire-resistant doorsets other than lift-landing doors, which are intended to protect trafficable openings in fire-rated walls: it covers required modes of exposure to standard fire tests, and lists permissible variations which may be made to doors without resubmission for prototype t esting. Installation, adjustment, inspection and certification and labelling are specified. Appendices include requirements for fireresistant doorsets for particular applications, notes on the selection of door closers,

56

ENA DOC 18-2008 – Interim Guideline for the Fire Protection of Electricity Substations and some suggestions on fixing of fire-door frames which are not built-in at the time of wall construction. AS 2427 - 2004 Smoke/heat release vents. Specifies construction and performance details for vents intended to be fitted in a building and to automatically open, on the outbreak of fire, to allow escape of smoke and hot gases. AS 2428 Methods of testing smoke/heat release vents. AS 2428.1 - 2004. Determination of resistance to leakage during rain. AS 2428.2 - 2004. Determination of ability to operate under wind loading. AS 2428.3 - 2004. Determination of operating characteristics. AS 2428.4 - 2004. Determination of effect of flame contact. AS 2428.5 - 2004. Determination of coefficient of discharge and effective aerodynamic area. AS 2428.6 - 2004. Determination of ability to operate under snow loading. AS 2430 - Classification of hazardous areas. Part 1 - 1981. Explosive gas atmospheres. Provides a classification of areas according to the likely existence of an explosive gas/air mixture, including areas in which the mixture is continuously present or present for long periods (Zone 0), areas in which the mixture is likely to occur in normal operation (Zone 1), and areas in which the mixture is not likely to occur or will exist only for a short time (Zone 2). Factors to be considered in the classification of areas are outlined and appendices deal with specific occupancies, and with basic principles of hazardous atmospheres. Part 2 - 1981. Dusts (including inherently-explosive dusts). Provides a classification of areas according to the likely existence of an inherently explosive dust or explosive dust/air mixture. Dusts are grouped according to their physical properties and three zones (3, 4 and 5) are determined according to the area where a particular dust is present. Appendices cover basic principles of dust hazards, experimental data, groupings of typical hazardous dusts, and illustrations of zones.

13.2. Detectio n and Suppressi on AS 1603 - 1997 Heat detectors for fire alarm installations. Covers the design, construction, marking, performance and testing of five types of detector for "rate of rise" and "fixed temperature" applications. Performance is prescribed in relation to insulation resistance tests and thermal tests (22°C/min., 6°C/min., 2°C/min. and 0.5°C/min.), together with an instantaneous rise of 20"C or 30"C according to type. Tests for resistance to corrosion, shock, crushing, low temperature, voltage excursion and transient voltage are also included together with test strength of screw threads and fixings. Recommendations on the selection of the type of heat detector arid on the application of fixed capacitors are given. AS 1670 - 2004 Rules for automatic fire alarm installations (known as the SAA Code for Automatic Fire Alarm Installations) Applies to the design, installation and maintenance of thermal detectors and smoke detectors and systems using detectors responsive to flame and any other automatic fire alarm system, including the method of connecting manual call-points to such systems. Definitions, general requirements applicable to ail systems and specific requirements for heat detection, smoke detection and flame detection systems are given. Appendices set out recommendations on the selection of types of thermal

57

detector and on the application of smoke and flame detectors, together with a standard form of installer's statement for a fire alarm system, and fire alarm symbols. AS 2362.23 - 1990 Automatic Fire Detection and Alarm Systems – Method of Test for Actuating Devices – Weathering Test. Sets out the requirements and tests for manually operated call points for use in conjunction with automatic fire alarm installations. It includes tests for corrosion, frangibility of covers, and impact. A weathering test is included for call points intended for mounting in positions exposed to weather. AS 2118.1 - 2006 Rules for automatic fire sprinkler systems (known as the SAA Code for Automatic Fire Sprinkler Systems) The first eight sections deal with general requirements and include information relating to classification of occupancies, water supplies, piping etc. The following three sections deal with the specific requirements for extra light, ordinary, and extra high hazard class system. Appendices cover the determination of orifice plate sizes, hydraulic requirements for extra high hazard systems and a specimen completion certificate. AS 7240 series on Fire detection and alarm systems, and in particular its Part 1: General and definitions, is a core fire protection standard (along with AS 1670) in respect of system design approach – refer to its Figure 1 – and the unifying definition of terms it contains. The series currently comprises: AS 7240.1-2007 Fire detection and alarm systemsGeneral and definitions

AS 7240.2-2004 Fire detection and alarm systems Control and indicating equipment (ISO 7240-2:2003, MOD)

AS 7240.4-2004 Fire detection and alarm systems Power supply equipment (ISO 72404:2003, MOD)

AS 7240.5-2004 Fire detection and alarm systems Point type heat detectors (ISO 72405:2003, MOD)

AS 7240.6-2006 Fire detection and alarm systems Carbon monoxide fire detectors using electro-chemical cells

AS 7240.7-2004 Fire detection and alarm systems Point-type smoke detectors using scattered light, transmitted light or ionization (ISO 7240-7:2003, MOD)

AS 7240.8-2007 Fire detection and alarm systems Carbon monoxide fire detectors using an electro-chemical cell in combination with a heat sensor

AS 7240.10-2007 Fire detection and alarm systems Point-type flame detectors

AS 7240.12-2007 Fire detection and alarm systems Line type smoke detectors using a transmitted optical beam

AS 7240.13-2006 Fire detection and alarm systems Compatibility assessment of system components

AS 7240.15-2004 Fire detection and alarm systems Multisensor fire detectors (ISO 724015:2004,MOD)

AS 7240.21-2006 Fire detection and alarm systems Routing equipment

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13.3. Exting uish ing Equipment AS 1221 - 1997 Fire hose reels Specifies design, materials, construction and performance requirements of fire hose reels permanently connected to a water supply. AS 1687 - 1991 Knapsack spray pumps for fire fighting. Applies to a hand-operated knapsack spray pump of the rigid water-container type. It specifies materials and construction of containers of metal and plastics with a capacity of up to 22 litres. Requirements for carrying straps, hose and pump are given, together with tests for the nozzle in the jet position and the spray position and a drop test for plastics containers. AS-1841.1 - 1997 Portable fire extinguishers – General Requirements. AS 1841.2 - 1997 Water Type Portable Fire Extinguishers. AS 1841.3 - 1997 Wet Chemical Type Portable Fire Extinguishers. AS 1841.4 - 1997 Foam Type Portable Fire Extinguishers. AS 1841.5 - 1997 Powder Type Portable Fire Extinguishers. AS 1841.6 - 1997 Carbon Dioxide Type Portable Fire Extinguishers. AS 1841.7 - 1997 Vaporising – Liquid Type Fire Extinguishers AS 1841.8 - 1997 Non-rechargeable Type Fire Extinguishers. AS 1850 - 1997 Portable Fire Extinguishers, Classification, Rating & Fire Testing. Sets out the classification, fire testing and rating of fire extinguishers used in attacking fires. AS 2419 - 2005 Installation of fire hydrants. Sets out the requirements for fire hydrant installation in properties, including location, spacing and water supplies. Covers hydrants both in buildings and in open areas. Although primarily installed for use by occupants, such hydrant systems may also be used by fire brigades. AS 2441 - 2005 installation of fire hose reels Specifies requirements for connection to water supply, location and mounting, and includes commissioning tests. AS 2444 - 2001 Portable Fire Extinguishers and Fire Blankets Selection & Location Sets out guidelines for the selection and location of portable fire extinguishers to provide minimum protection. It provides recommendations for extinguishers for industrial, commercial and domestic premises and vehicles, including caravans and boats.

13.4. Maintenance AS 1851 - 2005 Rules for the maintenance of fire protection systems and equipment. Sets out requirements for the inspection, test, preventative maintenance and survey of fire protection systems and equipment.

13.5. Other Aust ralian Standards Related to Fire Prot ection AS 1674 - 2007 Rules for fire precautions in arc or flame cutting, flame heating and arc or gas welding operations (known as the SAA Cutting and Voiding Safety Code)

59

Relates to protection of persons and property from injury by fire or explosion arising out of cutting, heating or welding operations. Preliminary precautions include the appointment of the responsible officer, inspection of site and issue of work permit. General precautions include reference to cutting, heating or welding in or near hazardous locations and in other locations, and set out essential safety measures to be taken before, during and on completion of the work. Cutting, heating and welding permit is illustrated in an appendix and a second appendix provides a recommended procedure for cutting, heating or welding containers used for flammable or explosive substances. AS 1875 - 1976 Domestic incinerators. Applies to up draught and downdraught types used for the burning of readily combustible domestic and garden rubbish and specified requirements aimed at reducing risk of spread of fire. It refers to top, flue, spark arrester, baffle plate, openings, screen and guards, and external apertures, but does not specify overall dimensions. AS 1940 - 2004 - The storage and handling of flammable and combustible liquids Provides rules for the planning, design and construction, and safe operation of all installations in which flammable or combustible liquids are stored or handled. In separate sections it deals with minor storage, package storage and handling, storage in tanks, fuel dispensing, piping and tank auxiliaries, heating of liquids, operations and fire protection facilities. Appendices deal with tank venting and combustion characteristics, and show a typical work permit. MP24 (1972) Use of lifts in emergencies (An examination by the SAA Committee on Lift Installations)

13.6. Emergency-Lighting-In-Buildings Substation buildings can be deemed Class 8 buildings if they are not pole mounted, kiosk, padmount, or modular type substations and should comply with the BCA, Part E4 ‘Emergency Lighting, Exit Signs and Warning Systems’ regarding substation evacuation provisions. The standards below are mainly intended for buildings used by the public - but can be used for guidance in substations. AS 2293 Emergency escape lighting and exit signs in buildings. AS 2293, Part 1 - 2005 System design, installation and operation requirements. Requirements for the equipment used and practices adopted in the installation of emergency evacuation lighting in buildings. Includes a system for classifying emergency luminaries according to their light output distribution, together with associated requirements controlling the maximum spacing which may be used. Does not specify the types of buildings which should be provided with emergency evacuation lighting. AS2293 Part 2 - 1995 Inspection and Maintenance procedures. Specifies periodic inspection and maintenance checks which should be carried out to ensure that emergency evacuation lighting systems will be ready ' for operation at all times. AS2293 Part 3 - 2005 Emergency Escape Luminaries and Exit Signs.

13.7. Natio nal Fire Prot ection Assoc iation (NFPA) Standards NFPA. No. 12 - Carbon Dioxide extinguishing systems. 60

ENA DOC 18-2008 – Interim Guideline for the Fire Protection of Electricity Substations NFPA. No. 15 - Water spray fixed systems for fire protection. This standard deals with water spray protection from fixed nozzle systems only. It does not cover water spray protection from portable nozzles or sprinkler systems. NFPA, No. 850

13.8. Summary of Aust ralian Practices The Insurance Council of Australia The above Council is concerned with the interests of Insurance Corporations and when a certain aspect of fire protection is not covered by the SAA it is prudent to require that it meet the standards set by this Council. Board of Fire Commissioners of NSW In New South Wales this is an advisory body until a fire takes place and then it has ultimate responsibility and authority. Similar authorities exist in other states.

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Transformer Safety Standards

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