ELECTRIC CABLE CONDUCTOR
WIRE CONSTRUCTION CONSTRUCTION
small cable wire big wire cable a conductor must be able to :transmit current efficiently minimal heat release during transmission resist fire for a considerable period light in weight Consist of inner conductors and outer layer of insulators for protection. It is important to use proper size of wire if wire is used that is large than needed , it is an unnecessary expense if wire is used that is too small, it will cause excessive voltage drop and damage the equipment. most people think of wire as having zero resistance . In actual practice, however all wire has resistance. There are four factors that determine the resistance of a piece of wire. The factor are : the diameter of the wire the material of the wire the length of the wire the temperature of the wire →
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INSULATORS Purpose : to resist current of heat flow. Common materials :- paper, wood, plastic, pvc, rubber, glass, porcelain and etc.
CABLE CONSTRUCTIONS CONSTRUCTIONS
Generally consists of :a) Conductor , either solid cores or several strands to one core. b) Insulator, one or several layers of different materials. c) Mechanical protection (if needed) of solid casing, steel wires or steel tapes. If a) + b) wires If a) + b) +c) cables Cables are more heavy duty and carry higher voltages than wires. There are two types of cable : 1. PILCSTA ( paper insulated lead sheath steel tape armoured ) 2. PILCSWA ( paper insulated lead sheath steel wire armoured ) →
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There are three (3) types :1. FLEXIBLE PVC Flexible cord ( 0.5mm² - 4mm²) household domestic wiring 2 small cores with several strands Flexible wires ( 6mm² - 630mm²) household permanent domestic wiring I core with several strands household appliance: 3 cores ( earth, neutral, live) with several strand.
2. HSOS ( HOUSE SERVICE OVERHEAD SYSTEM CABLE )
similar to flexible cords but with vulcanized rubber on the outer sheath and PVC insulators on the inner sheath. has 2 bigger cores and more durable to environment use to supply 1 – Ø, 2 wires between houses
3. MICS (MINERAL INSULATED COPPER SHEATHED)
heavy duty & durable water, oil, grease & chemical resistance can withstand until 150°C very expensive & for higher voltages
SELECTION OF CABLES AND WIRES Important criteria due to : -
Important factor are : -
SAFETY PROTECTION APPARATUS KILOWATT METER
» cost » safety » effectiveness effectiveness » durability » flexibility » optimum capacity » handling
» capacity of voltage & current » Insulation » Method of wiring » Usage » Moisture » Corrosion » Pest resistant » Ultra violet rays » Impact or stress » Cost
DUCTING Conduit circular ducting, smaller in size(up to 32mm Ø), GI & UPVC Trunking rectangular or square ducting bigger in size ( from 50×50mm to 125 ×
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305mm) UPVC & metal.
Main switch of the electrical system in home switches off and on that is the supply of electricity to the entire house. Before any electrical inspection or work is carried out such as checking and replacing a blown fuse. It is vital that the main switch is turned off. The main switch is located on the fuse box or the consumer unit.
ELCB ( EARTH LEAKAGE CIRCUIT BREAKER )
Purposes of ducting
» Extra protection against pest, accident etc. » Proper installation & alignment, grouping & aesthetic.
MAIN SWITCH
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A kilowatt meter is simply a gauge for measuring the amount of electrical energy something uses. One will find this device attached to any home or apartment that uses a commercial source for electricity. This power monitor is not equipped with the ability to send readings to the company and it is still read manually. Each reading period, generally one month, a r epresentative from the energy company goes to the home to conduct a reading to determine the electrical usage for billing purposes
Fittings : elbows, tees, crosses, inspection windows, saddles Nowadays UPVC conduit & trunking are preferable compare to metal due to light weight, non- corrosive & cheap
An Earth Leakage Circuit Breaker (ELCB) (now referred to as residual current circuit breaker) is a safety device used in electrical installations with high earth impedance to prevent shock. Responsibilities Responsibilities of house owner Automatic switch off main supply if 1. Short circuit 2. Lighting strike Automatic switch off main supply of short Lighting strike by earthing the extra Current to earth, thus protecting humans. Four types : current operated, heat operated, magneto hydraulic & electronic.
TRAY
Cable of wire tray is installed by suspension wires under the ceiling or by screw to the wall. It is the metal tray with different sizes of holes so that plastic or aluminium grip can hold the cables or wire to the tray.
FUSES
MAIN SWITCH
Responsibilities Responsibilities of house owner To switch off ( cut off ) main supply manually for maintenance or etc. Two types : for industrial industrial / workshop ( 3-Ø) & house (1-Ø)
To cut out current circuit due to excess current flow by using conductor ( fusible material ) melting at certain temperature. For domestic supply, certain locations are placed fuses for extra safety. Three types : rewirable fuse, cartridge fuse & high capacity fuses.
MOLDED CASE CIRCUIT BREAKER (MCCB)
Wide range: 25A to 1600A (AC) - Thermal magnetic type and electronic electronic type, fixed and adjustable version version - Compact dimensions, 1P, 2P, 3P, 4P - Adjustable thermal setting and magnetic setting - Suitable for use as switch disconnector - Push to trip button provision - Positive dolly position indication indication - Wide range of accessories
MINIATURE CURRENT BREAKER(MCB) MCB’s function is like fuse where it protect the electric circuit wiring system
from supercurrent which triggered by overload or short-circuit. If the current rate exceed the MCB rate, then the MCB will jerked and must be reset to so that the circuit could be linked again.
RESIDUAL CURRENT CIRCUIT BREAKER(RCCB)
SOCKET
The current flow of electrical system is always very hazardous and involves high risks. Complacency in the part of the electrical enginee or wrong wire connection can lead to serious damage by way of electrical shock circuit. This can cause leakage in current. Earth leakages is a electrical hazard and may cause fatal damage by way of electrical shock circuit. This can be protected by way of residual current circuit breaker. It is otherwise known as Earth Leakage Circuit Breaker (ELCB ).
Socket is a panel that have three hole. Each hole has it main function which can allow the current to flow to earth, live and neutral line. It also has a switch to turn the current flow or not.
SWITCH
A switch is a mechanical device used to connect and disconnect a circuit at will. Switches cover a wide range of types, from sub miniature up to industrial plant switching megawatts of power on high voltage distribution line.
