Extractor Fan - Utility Room

[nick60]

evening all, my sparky is booked for two weeks time but he's currently on holiday so I can't get him to advise on this. Myself and the builder need to get on with boarding and skimming a stud wall tomorrow but I know we're going to need some wiring for an extractor fan in there. It's a utility room, the only window is a velux in the roof (likely to be opened only rarely I would think). My plans indicate an extractor fan, but it's the detail I'm stuck on;

1. Is it OK to have an extractor with a simple on/off pullcord rather on a timer?

2. If I have an extractor with no timer, is it OK to just have the on/off pullcord and no isolator switch? Fan will be on a 6A lighting circuit

3. I think I read somewhere that you can do this, but you need a pullcord switch with some minimum gap between the switch contacts. Is this correct? (I can't remember where I read this)

Hope someone can help! TIA

Nick

 

[stem]

Please see comments below your questions.

1. Is it OK to have an extractor with a simple on/off pullcord rather on a timer? Yes, the run on timer is only a requirement for rooms such as bathrooms & W/C's that don't have an opening window, or other method of ventilation.

2. If I have an extractor with no timer, is it OK to just have the on/off pullcord and no isolator switch? Fan will be on a 6A lighting circuit. No, you will need an isolating switch that breaks both Live & Neutral conductors for servicing purposes. Normal pullcord light switches are single pole.

3. I think I read somewhere that you can do this, but you need a pullcord switch with some minimum gap between the switch contacts. Is this correct? (I can't remember where I read this) Probably in the instructions that come, or will come with your new fan. If you haven't purchased one yet, then find what you want on the internet and you will usually find instructions on there too. Click here for an example.

 

[OwainDIYer]

3. Usually you need a 3mm contact gap for isolation and a mechanical off indicator. The switches sold for electric showers will be suitable eg
http://www.tlc-direct.co.uk/Products/MK3164.html

50A is a bit overkill ...

However in a utility room (no shower or bath) there would be no problem about having an ordinary FCU (fused connection unit) off either the power or light circuit for isolation, and an ordinary 5A pullcord lightswitch somewhere more convenient if, erm, convenient.

 

[nick60]

OK, thanks for the replies. So I think the simplest thing is to bung in a 2 pole isolator switch and then use a single pole pullcord to switch it on/off. Just one final question, whats the recommended order of components .....

is it

supply--isolator--on/off switch -- fan

or

supply--on/off switch--isolator--fan

cheers
Nick

 

[stem]

Doesn't really matter. Most are wired

Supply - Isolator (Double pole)- Pull Switch - Fan

That way the isolator isolates everything. Because it's a utility room, you could dispense with the pullcord and use the isolator to switch the fan on and off. Having said that it you're likely to want to operate it with wet hands probably best to keep it in.

 

[nick60]

thank you stem. that's good because that's how we arranged things! cheers

 

[stem]

Sorry, my reply was a week later. Summer holiday season.