DIY extractor fan wiring

[pjgtech]

Hi, DIYer here, also 1st post (gulp!)

I've lived in my house for 30 years, we have always had a 100mm pull cord type extractor fan in the bathroom. Over the years it has stopped working and I have simply disconnected, taken out old one, and put in a new one (same type, eg: pull cord). No probs... However....

Just had a new boiler and HW cylinder installed in the airing cupboard, and the gas engineer informs me that the extractor fan is connected to the immersion heater wiring, which is not allowed, so he has disconnected it. Which is fine by me, I was not aware of where the supply came from, and assumed it was ok?

But I now need to connect the extractor fan to some other suitable electrical supply.
Can I simply connect a pull cord type extractor fan to the existing lighting circuit in the bathroom? if so will the pull cord still owrk, or will it only work if the light is on?
Or do I need to get a new extractor fan as well as the new connection / supply? (suitable for a light circuit connection).

Cheers

 

[MJPD29]

It can be connected to the lighting circuit thrpugh a fuse spur usually but it depends on the manufacturers instructions. Worth looking up to check. I wouldn't let a 'gas engineer' go round my house disconnecting things either, its not his job nor business to do so. If your in any doubt contact a qualified electrician.

 

[pjgtech]

It can be connected to the lighting circuit thrpugh a fuse spur usually but it depends on the manufacturers instructions. Worth looking up to check. I wouldn't let a 'gas engineer' go round my house disconnecting things either, its not his job nor business to do so. If your in any doubt contact a qualified electrician.

I think its cos I had a new HW cylinder and immersion heater installed, along with the new boiler, so he was disconnecting old Imm Htr and connecting new one? cheers for the info...

 

[Lucien Nunes]

He might have discovered some problem with the extractor wiring and been unwilling to reconnect it to the circuit that he was working on and had to sign off. One possibility is that it was not fused or RCD protected correctly. But it might still be possible to reconnect it to the existing supply with suitable modification, and therefore avoid running any new cables

 

[pjgtech]

I was thinking maybe that the immersions heater is presumably 13A, and is via switched fused connection, but I would imagine that a small extractor fan would only need 3A or 6A?

 

[Lucien Nunes]

A typical fan will use 0.1 - 0.2A maximum

 

[Dartlec]

The pull cord you are referring to is on the fan I assume?

If it was connected to the light directly, it may only be powered when the light is on, but it may also be possible to connect it so that it works independently - it would depend on how your bathroom light is wired. If the cable from the fan to the airing cupboard runs above the ceiling near to the bathroom light then it may be a relatively simple job, but would need some experience of lighting wiring.

Is there any other power within the airing cupboard other than the immersion heater?

 

[pjgtech]

The pull cord you are referring to is on the fan I assume?

If it was connected to the light directly, it may only be powered when the light is on, but it may also be possible to connect it so that it works independently - it would depend on how your bathroom light is wired. If the cable from the fan to the airing cupboard runs above the ceiling near to the bathroom light then it may be a relatively simple job, but would need some experience of lighting wiring.

Is there any other power within the airing cupboard other than the immersion heater?

Hi thanx for reply, yes, the pull cord is on the fan, and yes there is also the power supply for the boiler and CH / HW programmer, pump, motorised valves, etc, in the airing cupboard.
The extractor fan cable is still in the airing cupboard, (not connected at that end) and as you say it runs up into the loft, over the ceiling and down an opposite wall to the extractor fan, so it could easily be connected to the bathroom lighting circuit as it passes right next to it in the loft.
Cheers

 

[Dartlec]

Hi thanx for reply, yes, the pull cord is on the fan, and yes there is also the power supply for the boiler and CH / HW programmer, pump, motorised valves, etc, in the airing cupboard.
The extractor fan cable is still in the airing cupboard, (not connected at that end) and as you say it runs up into the loft, over the ceiling and down an opposite wall to the extractor fan, so it could easily be connected to the bathroom lighting circuit as it passes right next to it in the loft.
Cheers

Do you know if there is RCD protection on the lighting circuit?

If there is, then connecting it to the lighting circuit sounds like the best option (without seeing the installation)

First the usual disclaimer - don't attempt wiring unless you are confident in your abilty to work safely and can test that you have isolated a circuit before working on it. If at all unsure consult a competent electrician.

Second - if the fan is within one of the zones of the bathroom, doing this work may be considered to be notifiable under Part P of the Building Regulations, in which case it should be done by a registered competent person with one of the schemes (NICEIC, NAPIT, STROMA, etc).

Third - it may be sensible to include an isolator switch in the wiring, so that any future replacement can occur without isolating other circuits. The fan manufacturer may recommend or require this, and they may also require a lower fuse rating than the lighting circuit generally (such as 3A). If so, fitting a switched fused spur in the loft would be an easy way to do that in your case.

The permanently live cable will need to be identified and the cable suitably connected to that, rather than the switched live cable, then it will operate whether the bathroom light is on or not.

If all that sounds beyond you, it should be a fairly simple job for a local electrician and maybe an hours worth of labour.

 

[pjgtech]

Do you know if there is RCD protection on the lighting circuit?

Hi, thanx again for the info, yes the bathroom light is on the first floor lighting circuit, which is protected via RCD on the consumer unit.
Think I will get a local leccy to sort me out, great info thank you.