Wiring a humidistat Bathroom extractor fan.

mark3178 · 11 May 2008

I have a humididstat fan to install from scratch.
The fan has a live, neutral and switched live terminal.
I wondered if i could bring a live and neutral direct from a lighting circuit, via a fan isolator switch(positioned outside the bathroom) straight into the fan, removing the need for a switched live.

The idea being the fan would come on when needed(as humidity increased) working independently of the lights.

I also need to know wether I need to include a 3amp switchable spur, if i'm using a fan isolator switch, if so should this be fitted between the fan and iso switch or iso switch and existing light circuit?

All advice welcomed, as long as it's good advice.

GaryMo · 11 May 2008

Yes, that should work fine.
You don't need a fused spur as you're connecting to a lighting circuit which should be protected by a 5, 6 or 10A device. This is assuming the cable you're using is adequate.

breezer · 11 May 2008

never seen one, but you may have to link the live to switched live in order for it to work.

GaryMo · 12 May 2008

breezer said:
never seen one, but you may have to link the live to switched live in order for it to work.

If you do that the fan will probably run continuously, 24-7.
The humidistat will switch the fan on automatically when humidity rises as it's fed from the permanent live.
The switched live is for connection to the bathroom light so the fan turns on and off (with timer).

breezer · 12 May 2008

I did say

breezer said:
but you may have to link the live to switched live in order for it to work.

i didnt say you must

GaryMo · 12 May 2008

breezer said:
i didnt say you must

I'm just pointing out what would happen if he did as you suggested.

breezer · 12 May 2008

fine, i did not take any offence, i was thinking the other way round, it wont (may not) work unless the lights are on, to start it, then the humidistat bit makes it over run

GaryMo · 12 May 2008

No worries Breezer

I've fitted Vent Axia humidistat fans with overrun timers and they seem to operate independent of the switched live. Great for basement conversions.

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Wiring a humidistat Bathroom extractor fan.

mark3178

GaryMo

breezer

GaryMo

breezer

GaryMo

breezer

GaryMo

DIYnot Local

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