3-pole isolator switch for bathroom fan

Latin · Oct 7, 2013

Hi,

I have replaced an old bathroom fan wired to the light pull cord with a timer/humidity control one.
I realize I need a permanent live as well as a switched one for this.
This is an attic and the fan/duct goes out to the roof.
I have access to the loft above and I intend to rewire from the pull cord wiring and run a three core to the fan.

Is an isolator switch an absolute legal requirement? It appears it is for servicing purposes only and for that I can always switch off the radial from the CU like I have always done.
Should I have to install one, can I fix the switch to the bathroom ceiling next to the fan? The ceiling is quite low (2.5 mt) and I can easily drill into it from the loft to let the wires in and out, instead of chasing through the wall and causing serious disruption.

Many thanks
Latin

Badged01 · Oct 7, 2013

Its debatable whether you need an isolator or not but my interpretation of the regulations is you dont -- others will disagree so hear them out and take your pick!

The main argument hinges around if you dont fit an isolator when the lighting circuit is isolated for you to work on the fan, you cant see what you are doing because there's no light. OK, but what do you do for lighting if you want to work on the light fitting and you've isolated the lighting circuit anyway? If you've got an bright window in the bathroom then the argument is even less important.

As for needing local isolation for the fan you've hit the nail on the head, you trip the breaker at the CU -- as we all know working on any circuit you have to safely isolate it first be it the fan or the light! Not an ideal way to isolate but nothing in the regs prevents that being your method of isolation, but again a debatable point on regulations interpretation!

Think what you will find though is the 'new' fan will require fusing (normally on the manuf instructions) which generally means the circuit leading to the bathroom light has to be fused too. Pays your money takes your choice as to whether you fit an isolator at the same time, but for me the regulations dont require an isolator! (unless in addition to a fuse the manuf also wants an isolator fitted of course!)

Octopus · Oct 7, 2013

What do the fan installation instructions say. BS7671 states you have to follow such instructions........

Latin · Oct 8, 2013

Hi and thanks for replies.
Instructions say a 3 Amp fused isolator should be fitted.
Going back to my original questions, can I fit an isolator on to a bathroom ceiling as opposed to a wall?
If I could do that I would probably fit one anyway.

Cheers
Latin

Octopus · Oct 8, 2013

Latin said:
Hi and thanks for replies.
Instructions say a 3 Amp fused isolator should be fitted.
Going back to my original questions, can I fit an isolator on to a bathroom ceiling as opposed to a wall?
If I could do that I would probably fit one anyway.

Cheers
Latin

Seen it done - it looked awful. But if its outside zones....

SirKit Breaker · Oct 8, 2013

I have seen isolators installed in the loft. as long as you can get at it, and as murdoch says it outside of the zone, then carry on.

Cheers........................Howard

HandySparks · Oct 8, 2013

SirKit Breaker said:
I have seen isolators installed in the loft. as long as you can get at it, and as murdoch says it outside of the zone, then carry on.

Cheers........................Howard

In fact, if the fan is located in the loft and serviced by entering the loft, that is my preferred location for the isolator.

Des 56 · Oct 8, 2013

HandySparks said:
In fact, if the fan is located in the loft and serviced by entering the loft, that is my preferred location for the isolator.

That's where I thought it was located by his description,then reading him again,it seems its on the bathroom ceiling

He also contradicts himself throughout the thread

Latin · Oct 8, 2013

Hi,
I was trying to keep it simple, but it appears that my description is confusing.
So here we go:
I live in a converted Victorian house and I have the top floor. The roof is sloped like you would imagine. The bathroom ceiling, being under the roof, is partly flat and partly sloped. The fan and the pull cord and the ceiling rose are on that flat side of the bathroom ceiling. I have access to the loft space above through a hatch in the landing where I can get to all the bathroom wiring. It is a mask job, I have to lift the insulation and I don't fancy working there at all, but I can if I have to.
I certainly wouldn't put an isolator in the loft as the less I go there the better I feel. In that loft I can also see the fan duct shooting up to the top part of the roof from the bathroom.
I do intend to go up in the loft and rewire the fan from the pull cord so that I can have the extra (permanent) live. At the same time I could drill into the bathroom ceiling between the pull cord and the fan to let the wires through so that I could fit an isolator right there on the bathroom ceiling with minimal disruption, if I was allowed to, and that was one of my questions.
Thanks