Electricity in the
home.
The ESB supplies 2 cables to your home, one cable the live is maintained at 230V AC relative to the other. The neutral (zero potential ) cable is earthed at the ESB sub station. These cables are connected directly to the ESB meter. The meter measures the amount of energy in kilowatt hours used. The 2 cable then pass through a main isolating switch on the fuse board. The fuse box contains either fuses or circuit breakers. The ESB supply then connects the lights and sockets via the fuse board.
There are 2 main circuits used in the home
1)
Ring main circuit
2)
Radial circuit
Ring Main circuit
(Sockets)
The live and neutral wires each form a ring or loop. A third loop is formed by the earth wire. When an electrical appliance is plugged in, the live and neutral pins connect directly with the live and neutral wires, no current flows in the earth wire unless a fault develops, and the current flows harmlessly to earth. In a ring circuit there are 2 independent paths for the current to any point. This reduces the thickness of the wire.
Radial circuit
( lights)
The wires in a radial circuit go directly to the lighting points. The currents flowing in these circuits are small.
Spur sockets- (avoid if possible)
This is an extra socket connected to an existing ring main socket- A maximum of only one should be used per socket.
Switch
The live wire is always connected through the switch. This is essential for safety. If the live wire was connected directly to the appliance, it would be at 230V even in the off position!! The fuse is always on the live wire for the same reason.
Fuse- a very short length of wire with a low melting point. If a circuit becomes overloaded – to big a current flows, the fuse melts and breaks the circuit.
A large current caused by an overload in a circuit could cause
a) damaged electrical appliances
b) Overheat the house and cause a fire
Most fuse boards have cartridge fuses to protect each part of your house wiring. When these fuses burn out the colored disc on the end falls off.
Plug top fuses normally come in 2 strengths- 3 amp and 13 amp. 3 amp is adequate for appliances up to 650w- lamps, televisions etc.. 13 amp fuses are required for appliances over 650w- heaters, kettles, hair dryers etc. Check the appliance rating plate in case of doubt.
|
6 amp |
green |
lights |
· |
|
10 amp |
red |
lights |
· |
|
16 amp |
grey |
socket outlets radial circuit |
· |
|
20 amp |
blue |
immersion heater |
· |
|
35 amp |
black |
4 plate cooker & socket outlet ring circuit |
· |