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Wiring a Fused Extractor Fan Isolator

Postby AzK » Fri Dec 25, 2020 10:37 am


I am installing an extractor fan that has a built-in humidstat and timer. I ordered a
'10A 3 Pole Fan Isolator Switch with 3A Fuse' to combine having both a fan isolator switch and a FCU.

Has anyone wired one of these up before or would they have a good idea how to do it? It's more the 'L in' and 'L out' element on the back of the fuse that I am not sure about.

The fan is a Xpelair CV4SR that has 3 connections (T-L-N).

I am planning to wire:

L1: Black (Switch live) to 'T' (within the fan unit)
L2: Brown (Permanent live) to 'L'
L3/N: Grey (Neutral) to 'N'

That being the case, where do L in and L Out wire into?
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Simply Build It

Postby Mr White » Sat Dec 26, 2020 12:05 am

Connect it as you said. BUT, instead of the permanent live going to L connect it to L in on the fuse, then connect a small wire from L out on the fuse to L on the isolator.
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Postby mckaymmc1 » Sun Jan 24, 2021 1:25 pm

The fuse ie the Lin and Lout terminals needs to be wired into the permanent live circuit between the isolator and the fan - not the switch lived circuit.
I would connect it slightly different to Mr White but it makes no difference as long as the fuse is down stream of the isolator and in the permanent live circuit.

Fan manufacturers are cagey about whether local fuse protection is required. Vent axia initially insisted on it for a 1400+ bedroom build but then backed down when challenged. Safest option is to install local fuse but TP isolators with this built in arent yet common.
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