Extraction fan in toilet wired into light - but need overrun

[3549950]

Hi guys, hope you're all well.

We've converted an existing commercial premises (workshops) into a new one (physiotherapy clinic). However we've come into a problem with the toilets!

Essentially the electrician who did the work wired the vent in the toilet from the light circuit. So essentially the extraction fan comes on when you turn the lights on. So far so good.

However, our BC man has informed us that it must have an overrun, as there are no windows. However, the problem we've got is that as soon as you walk out of the toilets and turn the lights off, this of course kills power to the whole room - essentially stopping the fan.

Of course, we could rewire the whole lot (and I'm taking this up with my electrician obviously). However is there a simpler solution? Are there different extraction units available with a battery which trickle charge and then run the fan for a set period when the power is cut *hopes*

Does anyone have any ideas? Me and Mr Building Control both don't want to fall out over this, and I also don't want to run new power to the rooms!

Many thanks -

Dominic

 

[JohnW2]

Essentially the electrician who did the work wired the vent in the toilet from the light circuit. So essentially the extraction fan comes on when you turn the lights on. So far so good. ... However, our BC man has informed us that it must have an overrun, as there are no windows. However, the problem we've got is that as soon as you walk out of the toilets and turn the lights off, this of course kills power to the whole room - essentially stopping the fan. ... Of course, we could rewire the whole lot (and I'm taking this up with my electrician obviously). However is there a simpler solution? Are there different extraction units available with a battery which trickle charge and then run the fan for a set period when the power is cut *hopes*

I wouldn't have thought so - I've certainly never heard of such a thing. Apart from anything else, it would only be able to 'trickle charge' the battery when the light was switched on, which probably wouldn't be for all that much time!

However, the amount of change o the wiring might be very little. You'd need a new extractor, with a built-in over-run timer (or, alternatively a separate over-run timer, but that might well be almost as expensive). However, it's quite possible (but not certain) that all your electrician would have to do would be to replace the 2-core cable from light to extractor with 3-core, which might well not be a very big job at all.

Kind Regards, John

 

[mfarrow]

You won't fall out with the BCO, because the BCO is correct, and has to enforce the regulations.

I am assuming you lack a permanent live at the fan to allow you to fit a fan with an overrun. Correct?

If so, either rewire a permanent live to the fan or, and this might be a lot easier, replace the light switch with a flush ceiling PIR with tmer, so both light and fan go off x minutes after leaving the room. You'll need a neutral, but at least it will be mounted in the ceiling where one should be available more readily.

 

[Iggifer]

I thought that but being commercial it likely isn't fed from a rose like it normally would be - but, that being said, it's likely only looped at the switch or a JB in the ceiling, so potentially just as easy (or a little more if it's looped at the switch)

I wouldn't waste time looking for a battery fan, just get the spark back to add you a permanent live

 

[3549950]

Righty ho.

Sounds like a job for my electrician - time to give him a call, get him back and confiscate his car keys until he fixes it!

Thanks chaps!

 

[JohnW2]

I am assuming you lack a permanent live at the fan to allow you to fit a fan with an overrun. Correct? ... If so, either rewire a permanent live to the fan or, and this might be a lot easier, replace the light switch with a flush ceiling PIR with tmer, so both light and fan go off x minutes after leaving the room. You'll need a neutral, but at least it will be mounted in the ceiling where one should be available more readily.

My thinking was that there's probably as likely to be a permanent live in that ceiling (where the light presumably is, hence where feed to fan probably comes from) as a neutral - either in a rose/light fitting or a JB. The biggest pain would probably be if the perm live was looped at the switch. Similar to your idea, an alternative might be to replace the light switch with a push button 'delayed off' one, which would result in both light and fan staying on until x minutes after you'd entered the room and switched the light on.

Kind Regards, John

 

[securespark]

It's a long way off that high horse, Ban.

There are so many things you don't know.

It's a commercial premises. It could easily be that the job was arranged by a builder or even architect (as the premises has had a change of use).

So they could well have told BC they would comply by fitting an ORT. The spark may have misread the spec (or scrimped on the parts, or fitted what he had on the van - who knows?)... the point is you can't jump in like a Rottweiller all the time and make assumptions.

 

[mfarrow]

might be to replace the light switch with a push button 'delayed off' one, which would result in both light and fan staying on until x minutes after you'd entered the room and switched the light on.

That would certainly help reduce the duration of toilet breaks the staff take

 

[JohnW2]

might be to replace the light switch with a push button 'delayed off' one, which would result in both light and fan staying on until x minutes after you'd entered the room and switched the light on.

That would certainly help reduce the duration of toilet breaks the staff take

I'm not so sure about that - 'x minutes' would have to be quite a long time, because it would presumably have to ensure the minimum period of over-run (probably 15 mins) after the room had been vacated, in order to satisfy Part F!

Kind Regards, John

 

[mfarrow]

have to ensure the minimum period of over-run (probably 15 mins) after the room had been vacated, in order to satisfy Part F!

That number rings a bell. You still might need to think about what you eat the night before, and don't even think about taking a book with you!

 

[JohnW2]

have to ensure the minimum period of over-run (probably 15 mins) after the room had been vacated, in order to satisfy Part F!

That number rings a bell. You still might need to think about what you eat the night before, and don't even think about taking a book with you!

As I said/implied, I don't think that's the user's problem. I presume that, to comply with the spirit of Part F (which IIRC requires 15 mins run-on after the light is manually switched off), if one was (which I was!) thinking in terms of a fixed 'on' time', the designer would have to consider the worst possible case of what a user might have eaten the night before, what book(s) they might take in with them, and what else they might be doing in there, and then add on 15 mins to get the minimum fixed 'on' time

Kind Regards, John

 

[JohnW2]

Whether you are able, or even inclined, to 'change your ways' is not something I know with certainty.

I'm supposed to take that sort of thing on board as valid criticism, accept that the critic is right and I need to change? In your dreams.

I think you do now John!

Fair enough (hardly unexpected!). In that case, when he wrote "There is now nothing I can do about the way that a number of people behave towards me.", he really should have written "There is now nothing I am prepared to do about ..." - and if that's the case, then he simply has to lie on the bed which he's made for himself, so long as he continues to be allowed to.

Kind Regards, John

 

[Johnmelad]

Sorry, wrong topic

 

[JohnW2]

Off topic posts removed. Back on topic...

At last! Thanks. I think 'the topic' was actually put to bed (by the OP) in post #5! ("Righty ho. Sounds like a job for my electrician - time to give him a call, get him back and confiscate his car keys until he fixes it! Thanks chaps!")

Kind Regards, John