Wiring a Humidistat Bathroom Fan Using a Separate Switch Which Does not Turn on the Light

Postby Jimbotrip » Wed Jan 10, 2018 7:17 pm

Hi I am currently revamping my toilet. I am Good at DIY and do most of my jobs. I have installed 4 downlights. Removed the cord switch and replaced it with an outside switch in the hall. I have installed an LED mirror and have started to install an xpelair humidistat timer fan. I have it in position and connected it to three core and earth cable. I realise that the earth is simply sheathed. I have wired the brown cable to the live in the fan, the black to the neutral and the grey to the timed terminal. I have a lighting spur as my mains source.
Now the advice that I require is for you to explain how to connect this. I have a 1gang 2way switch and I also have a 3pole insulating switch. I would appreciate if you could start your explanation from my power source and tell me where to connect each cable to. I have extra cable (3 core and earth and 2 core and earth. Sorry the final thing to say is that I did not want the fan to come on when I switch on my lights. That is why I want to use a separate switch.
I hope someone will be able to assist me with this.
Many Thanks
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Simply Build It

Postby ericmark » Wed Jan 10, 2018 10:49 pm

Forgetting about earth which must be there even if not used.

Three cores from fan to isolator, then two cores to mains supply neutral and permanent line, and two cores to start switch which would be spring return permanent line and switches line.

The isolator could go other side of switch if you wish I am assuming standard three pole isolator which has fan logo on it.

Wired this way pressing or flicking switch as you enter will start the fan and leave it running for 15 minutes, however if the air is still damp it will continue to run.

In the main we use a PIR rather than a manual switch, the problem with a humidistat is if it gets water rather than just humid air on it then it just will not stop, so it must be running before you start using the bathroom or by time it detects enough humidity the air is already too humid to stop the water condensing on the sensor.
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Postby Mr White » Thu Jan 11, 2018 5:42 am

You connect your supply to one side of the isolator switch. From the other side of the isolator switch it goes to the fan.
You then take a twin and earth from the fan to your "Normal switch" One wire goes to the fan live, the other wire goes to the fan "timed terminal"

What colour does what is................up to you, but mark the live and switched live with brown sleeving.

All the earths get connected to the appropriate terminals.
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Postby Jimbotrip » Tue Jan 16, 2018 2:55 pm

Thank you very much for replying to me and for replying so fast. I had thought about the PIR but as it is my main toilet I thought it would turn on if I used the toilet during the night..
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