Bathroom Wiring

dsnd_medic · May 9, 2014

I am helping a friend with some bathroom wiring but I have a couple of things I am not sure of. His flat is an older one with a fuse box. I seem to remember from my regulation exam a few years ago that all bathroom wiring has to connected to an RCD in the fuse box....would that be correct ?

The other question I would like to ask is - is it good practice to connect a small ceiling extractor fan to the lighting power. He wants the fan to come on with the light rather than have an addition switch installed.......any comments would be greatly appreciated.

Thanks in advance for your answers

SPECIAL LOCATION · May 9, 2014

Regulation exam done a few years ago.... Do you still have a copy of BS7671???

Page 199 reg 701.411.3.3. is the one that says all circuits in the room containing a bath or shower need RCD protection...

maybe more than one RCD..

The RCD(s) may be at the fuse box ...

or may be a local standalone RCD..

or an RCD fused spur....

Whatever is the best solution..

Bathroom lights & fans....

A fan will not normally overload a lighting circuit so its all OK to supply it from the lights..

and as you say lots of fans with run-on timer use the light as the trigger to switch them on!

Guinness

ProDave · May 9, 2014

The regs are not retrospective so if the instalation is left alone, you don't have to do anything.

But new work, like adding a fan will require an upgrade to comply. you will need an rcd and you will need to check all earth bonding is okay.

Since it's a "fuse box" you won't be able to fit an rcd to that, so perhaps time to consider a CU upgrade? otherwise it's a stand alone rcd for the upstairs lighting circuit.

At least you don't have to notify this work to your LABC as you are in Scotland (off to get my tin hat. I didn't actually mention the unmentionable)

Yes it's fine to feed the fan from a lighting circuit, they draw much less power than a light fitting.

Andy™ · May 9, 2014

i often stick an RCD spur outside the bathroom for the lighting if its not practical to do it at the board

Evans Electric · May 9, 2014

Also manufacturer's instructions ask for a 3A fuse backing up the fan .....seperate from the lighting but you'll still need a 3 pole isolator as well .

{ note: It has been pointed out elsewhere not all manufactures instructions ask for a fuse or a 3pole isolator. But the majority of common fans used in a domestic environment do suggest some form of fuse and isolation.

Doc H. }