My daughter lives in a flat in Edinburgh. Recently she has had some
issues with fuses blowing. On investigation (by phone and photogarphs)
I've been amazed and alarmed to find that the consumer unit is simply
an 80A MEM fusebox with no earth fault protection devices.
A 9.5Kw shower is connected to a 30A fuse (which explains the blowing
When did UK or Scottish regulations require Earth Fault Protection?
Is there no onus on electricians in Scotland to ensure loads are
connected to suitably rated fuses.
There are no Scottish regulations in this context, the relevant ones are
those to the UK: - BS7671.
There is no requirement in the current regulations to fit RCD (earth fault
protection) to showers in any case, although there are manufacturers who
stipulate this. The future edition of the regulations: - 17th due in 2008,
will probably require this however.
The original earthleakage protection was voltage operated; and superseded by
the imbalanced current operated earth leakage protection, (the RCD) around
1981, as I can ascertain, so earth leakage protection per se, was introduced
sometime before. Older installations with fuseboards still conform to the
regulations: and there is no requirement to update for RCD protection,
unless there are alterations to the socket outlet circuits, where it may be
expected that portable appliances can be connected to these: -
Quote from the regs: -
471-16-01 A socket-outlet rated at 32 A or less which may reasonably be
expected to supply portable equipment for use outdoors shall be provided
with supplementary protection to reduce the risk associated with direct
contact by means of a residual current device having the characteristics
specified in Regulation 412-06-02(ii).
The discrepancy between the shower rating and the fuse size, is apparently
due to incompetence on the installer, what is the cable size?
I would recommend an inspection and report, by a competent electrician, at
least of the shower installation.
Always, in the form of EEBADS (Earthed Equipotential Bonding with
Automatic Disconnect of Supply). The fuses do the automatic
disconnection of supply when you short circuit the live to earth.
If you were thinking of RCD protection against electrocution, that's
only required in a few specific cases. This doesn't include a shower,
although you can optionally fit one if you wish.
Yes. Possibly it was a 7kW shower originally, although that's no
excuse. Combine that with your daughter possibly taking rather
long showers, and that gives the fuse a nice long time to warm up.
Note the cable may only be good for 30A too, so you can't simply
bump up the fuse without checking that too.
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