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Advice required on wiring for shower fan replacement

Postby MarkSolorize » Sat Oct 03, 2020 5:27 pm


I have an existing extractor fan, which I need to replace. But could do with a bit of help
confirming the wiring before I start the work.

In my ensuite I have a 'ceiling pull chord' for the fan which is separate to my light switch pull chord,
and currently do not have a fan isolator switch.

What I would like to do while replacing the fan is fit a 'Fan Isolator Switch' in the loft close by to the fan,
so I can isolate it in the future for maintenance.

I have looked at the fan pull chord switch and it seems to have the old coloured cables wired in.
I have ordered some new cables (the new colours), to wire the fan to the 'Fan Isolator Switch'.

The current fan had a run on timer function, as does the new replacement fan.

I have hopefully attached my interpretation of how I think the wiring should be done, but could do with
confirmation that I have it correct, before starting.

One of my concerns is that when looking on the internet, on how to wire the 'Fan Isolator Switch',
I have seen some people wire the 'permanent lives' into L1 and 'switched lives' into L2, as I have shown in my diagram,
but other have done it the other way around and put 'permanent lives' into L2 and 'switched lives' into L1.
Does this make a difference? or can it be done either way?

Also, could someone confirm if I have the correct old v's new wiring colours / names correct.

proposed wiring for replacement fan_1.png

Thanks in advance
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Simply Build It

Postby stoneyboy » Sun Oct 04, 2020 9:29 pm

Hi marksolarize
Connect your fan as shown in your diagrams. If the fan runs continuously swap the brown and sleeved black cable over shown in your middle diagram. Make sure the electricity is turned off at the consumer unit before you start.
Regards S
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Postby MarkSolorize » Sun Oct 04, 2020 9:58 pm

Hi Stoneyboy,

Thanks for your reply, and advice on switching the wires if the fan runs continuously.

Hopefully it will work right first time *fingers crossed*.

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