Circuits are important in the fact that without them you would not be able to run your TV, HiFi, lights etc. Your circuits are supplied direct from your Fuse Board/Consumer Unit and form Part of what is known as the Electrical Installation. An Electrical Installation in general is all the circuits, accessories etc within your property.
Circuits are referred to by a name and number with the lowest number normally being next to the main isolation switch of the fuse board. Furthermore it is good practice having the largest Fuse/MCB next to the main switch or in the case of a split load boards, and where relevant, next to the RCD or RCBO on the protected side. Modern day fuse boards could have the main switch on the left or on the right. the RCD/RCBO whilst normally being midway it has been known for them to be situated on the opposite end to the main switch.
Below is typical modern day layout of a fuse board in a house
Main Switch 100A Double pole to BS 60947-3
|
Circuit Designation
|
Circuit Name
|
Fuse Size (Amps)
|
Fuse Type
|
Cable Size Twin & Earth (mm²) |
Phase conductor size (mm²)
|
Neutral conductor size (mm²)
|
CPC (Earth) conductor size (mm²)
|
Notes
|
|
1 or 8
See Notes |
Cooker
|
32 or 40
|
B
|
6 or 10
|
6 or 10
|
6 or 10
|
2.5 or 4
|
If the cooker isolation switch incorporates a socket it should be on the RCD protected side and 'Immersion' would therefore take circuit 1 |
|
2
|
Immersion
Central Heating |
16
|
B
|
2.5 |
2.5
|
2.5
|
1.5
|
|
|
3
|
Lights Up Stairs
|
6
|
B
|
1 or 1.5 |
1 or 1.5
|
1 or 1.5
|
1
|
Properties normally have 2 light circuits regardless as to weather it is a flat, bungalow or house. This means that if if one light circuit fails, there is still some form of lighting. |
|
4
|
Lights Down Stairs
|
6
|
B
|
1or 1.5
|
1 or 1.5
|
1 or 1.5
|
1
|
As per Lights Up |
|
5
|
Smoke Alarms
|
6
|
B
|
1 or 1.5
|
1 or 1.5
|
1 or 1.5
|
1
|
Modern domestic smoke alarms can have two power sources, Battery and Mains. |
|
6
|
Spare
|
RCD 80A 30mA Double Pole
The following circuits have additional protection from the RCD
|
Circuit Designation
|
Circuit Name
|
Fuse Size (Amps)
|
Fuse Type
|
Cable Size Twin & Earth (mm²) |
Phase conductor size (mm²)
|
Neutral conductor size (mm²)
|
CPC (Earth) conductor size (mm²)
|
Notes
|
|
7
|
Shower
|
40
|
B
|
10
|
10
|
10
|
4
|
|
|
1 or 8
|
Cooker
|
32 or 40
|
B
|
6 or 10 |
6 or 10
|
6 or 10
|
2.5 or 4
|
See Notes for Circuit 1 |
|
9
|
Kitchen Ring
|
32
|
B
|
2.5
|
2.5
|
2.5
|
1.5
|
As the kitchen tends to draw the largest amount of power it is a good idea for it to have its own separate supply |
|
10
|
Upstairs Ring
|
32
|
B
|
2.5
|
2.5
|
2.5
|
1.5
|
|
|
11
|
Downstairs Ring
|
32
|
B
|
2.5
|
2.5
|
2.5
|
1.5
|
|
|
12
|
Spare
|
