DIY Doctor

Shower and light circuits under one RCD

Postby jackhawk » Sat Dec 13, 2008 4:40 pm


I have just installed a new electric shower circuit and light circuit to a bathroom. No space in existing CU so installed extra CU for shower. As per regs new circuits to bathrooms must be on rcds. So I have 63A 30ma main switch, 40A mcb for shower and 6 for light, both circuits under the rcd control. As all circuits should be installed to cause min inconveniance if a fault occurs, would you consider this arangement a min or max inconveniance. When LABC came for the first fix they never had a problem but I have been pondering over it. I could simply just reconect the light back on its old lights up circuit and remove the new mcb, but as an added safety feature I see my way as an acceptable incoveniance. The old way would see the accupier going down the stairs in complete darkness to the CU if a fault occured on the lights up. A fault on the shower would cause the light to go out in the bathroom and visa versa but the rest of the house would still be lit. Should I leave it as it is or disconect new light circuit? LABC inspecting and testing Tuesday so Monday is the crunch day. The cheap option is remove light mcb and have shower only, the expensive option is redo it with RCBOs.
Any thoughts?

Regards Jackhawk :oops:
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Simply Build It

Postby ericmark » Sat Dec 13, 2008 6:36 pm

The regulations do not say you need to fit all RCBO or duel RCD in consumer unit.
It is all to do with how your house is laid out. With my house there is a glass pain above every door upstairs to give light to the landing which has no window and as a result in my house even if I did lose bathroom lights I could still see enough to get out of the bath safely.
It is very unlikely the RCD you have fitted will ever trip and if it were me I would leave it as it is.
If sockets were also on same RCD then I would worry as anything could be plugged in and cause it to trip but with only a shower I would not worry as very unlikely it will ever trip.

Postby jackhawk » Sat Dec 13, 2008 7:05 pm

Thanks eric,

Feel alot better about it now. There is a large window with plenty of street lighting and the glass above the doors, as yours.

Many thanks
Take care

Rank: Tradesman
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Posts: 37
Joined: Tue Sep 04, 2007 9:02 pm

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