Fan switching on/off with lights - 2 bathrooms only one loft fitted fan.

[Matt H]

Hello all,

I had a professional electrician firm look into this when I was having my house re-wired and they said it wasn't possible, but I'm not so sure!

The scenario is - one large extraction fan in the loft and a set of extraction ducting that has a Y piece in it so it can extract from two separate bathrooms to the one fan. I wanted the fan to come on with either lightswitch being swiched on in either bathroom, and then go off again when turned off (no timers etc). This would mean that an empty bathroom was being extracted when the other one was being used, but to me that's not really a problem.

The electricians originally said they could achieve this with an extra core from each lightswitch to the loft, but having put in a set of extra cable runs, in the end they gave up and put two separate switches outside each bathroom - not ideal at all (the fan gets left on when the lights are off)

Any ideas, I think the issue the electricians were having was that the lights in the second (unused) bathroom would come on when the first one switched on, as the current would flow through the fan circuit. Saying that there were a few tales about irregular voltages and all sorts going on.

Your thoughts are much appreciated,
Cheers
Matt

 

[Taylortwocities]

I am assuming that you do not have dimmers in either bathroom?
In which case, simply chnage the light switches (which are single pole) to double pole switches.

Then you have a separate switched feed going up to the fan from both switches.

The other method is to use 230v relays one for each bathroom with the contacts being commoned to operate the fan.

There are other more complicated methods too, but need more logic/control circuitry.

 

[Matt H]

Hi there, no dimmers just switches. I was lead to believe that the lighting circuit would be energised in the other bathroom with this approach as the feed from one bathroom to the fan, would also flow from the fan back down to the other bathroom switch !?

 

[Leesparkykent]

Yeah double pole switches will do the job.

 

[Leesparkykent]

Hi there, no dimmers just switches. I was lead to believe that the lighting circuit would be energised in the other bathroom with this approach as the feed from one bathroom to the fan, would also flow from the fan back down to the other bathroom switch !?

with a double pole light switch at each position it will work. one of the poles switches the light and the other pole switches the fan. Just parallel the fan connections from each switch.

 

[Matt H]

..so how come the electricians couldn't puzzle this out..? They've wired my whole house ! :/

 

[Leesparkykent]

..so how come the electricians couldn't puzzle this out..? They've wired my whole house ! :/

Because they were stupid

 

[Taylortwocities]

I had a professional electrician firm look into this

does not mean competent, or capable

Unfortunately, many large electrical contractors employ grunts who are only able to do the standard stuff.

 

[Leesparkykent]

MK Logic K4876WHI Light Switch 1 Gang 1 Way Double Pole - http://www.gil-lec.co.uk/mk-logic-k4876-light-switch-1-gang-1-way-double-pole

 

[Taylortwocities]

wire it like this

 

[Silly Sausage]

View attachment 33961
does not mean competent, or capable

Unfortunately, many large electrical contractors employ grunts who are only able to do the standard stuff.

You should have quoted this too:
134 ERECTION AND INITIAL VERIFICATION OF ELECTRICAL INSTALLATIONS
134.1 Erection
134.1.1 Good workmanship by skilled (electrically) or instructed (electrically) persons and proper materials shall be used in the erection of the electrical installation.

I've just spotted a major flaw in the regs, 132 Design. doesn't specify the necessary abilities of the Designer, save that for the 18th

 

[Matt H]

Thank you very much all ! I must admit I did think they were making a meal of it. My next problem is that they haven't left me with a completion certificate... ho hum.

 

[Richard Burns]

Thank you very much all ! I must admit I did think they were making a meal of it. My next problem is that they haven't left me with a completion certificate... ho hum.

They should leave you an electrical installation certificate.
If the work is notifiable to building control (very likely on bathroom lighting) then a building regulations compliance certificate would (should) be sent to you later.

 

[Taylortwocities]

A Freire is certainly notifiable. You should have an Instsllation Certificate and a Building Regulations Certificate of Completion. The latter will come either from the Local Authority or from the Electrical Companies registration body (NICEIC, for instance).

 

[Matt H]

Oh its all notifiable - it was an extension to the property and renovation - full rewire of whole house, and yes all under building control. Haven't heard from the electricians since early june after they failed to wire the central heating system correctly either (fixed that myself).. I'm not in a brilliant situation on this to be honest.

 

[Matt H]

Oh its all notifiable - it was an extension to the property and renovation; full rewire of whole house, and yes all under building control. Haven't heard from the electricians since early june after they failed to wire the central heating system correctly either (fixed that myself).. I'm not in a brilliant situation on this to be honest. I've not gone for the completion from Building Control as I've not got what I need from the electricians yet

 

[Richard Burns]

Since the whole job was under building control then you will receive a building regulations completion certificate not a building regulations compliance certificate.
However you would need the electrical installation certificate(s) for the electrical work done.
It is not looking good from the electrical side of things if you have not heard from them for four months.
You may need a regularisation certificate instead!