timed extractor fan for downstairs toilet

5 Nov 2006
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United Kingdom

We need to get retrospective building regs approval and our cloakroom (just toilet and basin). Currently it has a bog standard fan that is controlled with the light switch cord.

We need to replace this with a timed one to meet the regs.

Looking on the net it seems timed extractor fans need 3 core and need to be connected to a 3 pole isolator switch. Out current setup just has fan connected by 2 core to a junction box with the lighting circuit, light switch and light.



I've been looking at wiring diagrams but not too sure. Is it ok to remove the 2 core from the junction box, connect a 3 core from the junction box to a 3 pole isolator switch and then have the isolator switch hooked up to a new timed fan?

If so, as it is only a cloakroom, I believe it would be OK to fit the isolator switch inside the toilet just above the door (quite near the light switch and fan).
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The junction box will need to be accessible for maintenance, inspection and test. It looks like you have had break in to the ceiling to access it.
If you cannot connect up without a junction/joint then you must use a method that is considered maintenance free (MF), you can purchase MF junction boxes!

To have overrun you will need three core and earth.

As the room does not contain a bath or shower, you will not require to notify building controls with regards to the alteration of an existing circuit.
You will need to comply to part p of the building regulations though, this mainly requires the installation to be safe.

So you need to prove that, this alteration will be deemed minor works and either a electrical installation certificate or a minor works certificate should be completed.
Any newly buried cable will very likely also require 30mA RCD protection.
the junction box is in the ceiling void, i pulled it down when I pulled out the fan to have a look.

I'll get a sparkie in though as we've got a few bits that we want doing. Cheers
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