Wiring a Replacement Kitchen Wall Mounted Extractor Fan


Postby Crassus » Sat Oct 20, 2018 7:22 pm

Hi all, I'm a newbie to the forum and I'm replacing a wall mounted extractor fan in the kitchen. The existing fan wasn't working when we bought the house, but it is wired on twin and earth cable (L, N) and is switched off and on by an isolation switch (no pull cord). I assume that it didn't have a timer. The new fan does have a timer and so has a terminal for a 3 core cable (L1, L2, N). So my question is, because I'm not too concerned about the timer facility can I get the new fan to work just by connecting it to the existing supply cable? If so, would I just connect the live supply wire to L1 (switched live) in the fan, or, do I need to connect the supply live to both the L1 and L2 terminals in the fan? Or is there a better solution?
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Postby Mr White » Sat Oct 20, 2018 10:27 pm

The answer to your question depends on the make and model of the fan. I would suggest you connect the live to one terminal and install a link to the other terminal.

A better solution would be to buy a fan with no timer.
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Postby Crassus » Sun Oct 21, 2018 9:18 am

Hi Mr White, thanks for your reply, it is really appreciated. Could I just ask, so instead of having the live supply coming to a junction block and then having separate wires comes from the junction block to the L1 and L2 terminals in the fan, are you saying that I should have one wire coming from the junction block to L1 in the fan and then a wire going from L1 to L2? Apologies if it sounds like a daft question but I just want to be sure. If there's no easy way to do this I might have to do what you suggest and just replace the fan for one without a timer.
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Postby ericmark » Sun Oct 21, 2018 11:01 am

I looked at wiring for Manrose Bathroom fan and there is nothing to suggest you can wire to switched line only, clearly would not work to permanent line only.

It has been talked about many times, if the switched line only triggers a supply from permanent line and does not actually feed the fan then only the permanent line would need a fuse, you could try it, but I would always fit the link.

In my kitchen the fan is built into the cooker hood, since I cook with electric never really worried about it, as to gas cooking, I have never seen an auto start when gas used, think it is left to the cook to turn on and off, but gas hobs the safety features seem to be conspicuous by their absence. No auto off timer if you walk away and forget, no auto off when you remove the pan, the list goes on.
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Postby Crassus » Sun Oct 21, 2018 1:03 pm

Hi Mr White, thanks for your response, it is much appreciated. Can I just confirm, so that I am clear, when you say 'install a link' do you mean take a single core of wire from L1 to L2 in the fan?
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Postby Crassus » Sun Oct 21, 2018 7:36 pm

Hi Mr White, thanks for your advice, it is much appreciated. I've tried to send a couple of responses but they haven't appeared for some reason. Hopefully this one will! Just to clarify then, when you say 'install a link' do you mean take a single core of wire from L1 to L2 within the fan? Just to give a bit more information, the old fan was 220-240 volts as is the new fan, but the old one was 40 watts whereas the new one is 20 watts. The cable from the isolation switch to the fan looks like 1.5 twin and earth as opposed to 2.5 twin and earth mains cable.
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Postby Mr White » Sun Oct 21, 2018 8:30 pm

First of all, the way this forum works is that when a post is made and then the submit button is clicked It then has to be viewed by a moderator to check to see if it is spam, or contains anything it shouldn't. If all is well the post then becomes viewable. As there is no moderator watching 24/7 we have to wait until a moderator becomes available, I am sure moderators only glance at posts (There are that many posts) so, so long as they see nothing offensive they will allow a post to become viewable, so that is why we can now all see that you posted 3 times.

Now to answer your question.

Yes.

When I say link I am indeed referring to a single piece of insulated wire taken from a twin and earth cable. (Preferably a red one)
1mm or 1.5mm cable is the size of cable I would expect to find supplying a fan, this is because extractor fans are normally supplied from the lighting circuit which uses 1mm or 1.5mm twin and earth. 2.5mm twin and earth is normally found supplying sockets.
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Postby Crassus » Sun Oct 21, 2018 8:48 pm

Mr White, that all makes sense and I now feel confident that I have a solution. I really appreciate your help and advice. Thank you.
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Postby Mr White » Mon Oct 22, 2018 7:13 pm

My pleasure, and thanks for the feedback.
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