Page 664 - The City and Guilds Textbook: Plumbing Book 1 for the Level 3 Apprenticeship (9189), Level 2 Technical Certificate (8202) and Level 2 Diploma (6035)

The City & Guilds Textbook: Plumbing Book 1

supply conductors. The colours for these conductors were red and black for
installations constructed up to 2004 and since then the colours blue and brown
have been introduced.

Meter
Main fuse

Consumer unit
Main double pole
switch on consumer unit
To water service
To gas service
Line and
neutral
cables Main earth terminal (MET)

Supply cable

p Figure 11.12 Fuse box

KEY TERMS The meter receives the electricity supply from the service head and measures the
consumption of power in your house. There may also be added components such
Meter: a display that as time clocks and switches if you make use of the ‘cheap rate’ night-time supply
enables the local company
to take readings for your bill. known as Economy 7. The dials on the meter record the number of units of power
Units of power: these are used so the customer can be billed. This then feeds the consumer unit via a pair of
read as kWh (kilowatts per large wires – one blue (old cable colour = black) and one brown (old cable colour
hour). = red). The wires from the meter terminate at a double pole switch (double pole
switches break both the line and neutral) inside the consumer unit. On the other
side of the switch, the neutral is connected to a neutral bar, which accommodates
all the blue (old cable colour = black) neutral conductors from your circuits.
The line, brown (old cable colour = red) cable goes to a bar, which sits behind
one end of all the fuses. The link from here to the terminal of each circuit is
protected by a fuse mounted between the two.

Another connector block called the main earthing terminal accommodates all
the earth (green and yellow) wires from your circuits and connects them back
to the main supply earth terminal.

On the consumer unit you will find switches you can touch to turn off and on as
p Figure 11.13 A meter point with
old wiring colours required. The main double pole switch is usually coloured red and will isolate all
the power to all of the circuits.

Next to this main switch you will have individual circuit breakers or other types
KEY TERM of circuit breakers that you can use to isolate a single circuit, again via a switch.
Permitted: being allowed to Remember that you are not permitted to remove the casing of the consumer
do something. unit or tamper with the cables – you must be a qualified electrician to do so.

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