All cables and connections to the consumer unit must be checked and
tested by a qualified electrician. Do not attempt removal or replacement
unless you are absolutely positive you know what you are doing, and
even then the above still applies. It is also an offence to interfere with
the seals on the electricity meter.
The modern consumer unit is the centre, or heart, of the wiring system
in the home. The unit distributes the electricity, via fuses of one kind or
another, to the different circuits in the house. The older fuse wire are
being replaced gradually by their modern equivalent, the MCB or
miniature circuit breaker.
We will deal with the two main types of consumer unit found in the home today . The first one
is a single load fuse board where the power coming in is taken through a double pole switch
to a live buss bar. Each fuse, or MCB, is clipped onto a DIN bar and the "teeth" of the buss
bar are inserted into the MCB's. The cables to the house circuits are connected to the other
side of the MCB's. All of this is explained more thoroughly when we deal with the second type
of unit, which is the split load unit. The photographs are of a split load fuse board. The
ordinary consumer unit is exactly the same in principle without the RCD.
Just as a matter of interest, DIN stands for Deutsche Industrie Norm and, originating in
Germany, is any of a series of technical standards, used Internationally, to designate
electrical connections, film speeds and paper sizes. Shown in the consumer unit casing
above, it is a metal, pressed bar, to which the MCB's clip. They simply push on via a spring
loaded lock at their back.
A split load board is designed for total safety and incorporates an RCD (Residual Current
Device, shown as E in the picture above) as well as the double pole switch (D).
The RCD is not just a manually operated isolating switch, but a very sensitive safety device
which cuts off in fractions of a second if it senses an earth fault. RCDs can be bought in