Replacing bathroom Extractor Fan - Do I need to add an isolator switch
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Replacing bathroom Extractor Fan - Do I need to add an isolator switch

by sameerp » Mon May 04, 2015 6:38 am

Hi all

I am replacing a bathroom extractor fan.
The old one is currently wired to switch on when the light is switched on, and then runs on for 20mins after the light is turned off. (There is a permanent live feed for the timer)

The old fan case broken, so I am replacing the whole fan with an IPX5 rated fan.
There is currently no double/triple pole isolator switch for the fan.
The fan is not isolated from the lighting circuit. For maintenance, have to turn the whole lighting circuit off. This is fine with us.

Current regulations for NEW wiring say that an isolator switch must be installed.
Is there a requirement to add an isolator switch when replacing fan?
Property will be let out if that makes a difference to teh answer.

Thansk for you help

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Re: Replacing bathroom Extractor Fan - Do I need to add an isolator switch

by ericmark » Tue May 05, 2015 3:30 pm

The regulations stipulate the size of motor before an isolator is required and a bathroom fan is too small to need an isolator. However regulations also say you should follow manufacturers instructions and most say fit an isolator.

I would always fit one because fans do fail and this could mean no lights.

[quote]314.1 Every installation shall be divided into circuits, as necessary, to:
(i) avoid hazards and minimize inconvenience in the event of a fault
(ii) facilitate safe inspection, testing and maintenance (see also Section 537)
(iii) take account of danger that may arise from the failure of a single circuit such as a lighting circuit
(iv) reduce the possibility of unwanted tripping of RCDs due to excessive protective conductor currents produced
by equipment in normal operation
(v) mitigate the effects of electromagnetic interferences (EMI)
(vi) prevent the indirect energizing of a circuit intended to be isolated.[/quote]

In theroy lights should not be supplied from the lights although they often are. I think it all comes under Part F which says when a fan is required and how it should be switched. If window opens no need for fan. But if there is a window and it does not open the fan must be able to be switched on without switching on the lights.

But regulations are only a problem when some jobs worth is inspecting or something goes really wrong. So do alterations in a bathroom and no problem until some thing goes wrong. Then courts look for some one to blame.

The [url=]Emma Shaw case[/url] is a good example. The mistake to my mind was made by either the person wiring leaving slack which plaster screwed through or plaster for screwing through the cable. Or the Plumber. But it was the Foremen who was blamed for using unskilled labour.

It was a one in a million error and to get caught is very slim but your letting out so only way is the paper trail. Every electrical job should have a minor works certificate or an installation certificate and depending who does the work and where you live it may need a completion certificate, building warrant or compliance certificate.

The person filling these in does not need to have an exam passed but needs to show they do know what they are doing. So in real terms it's not what regulations say but what the person filling in the paper work will accept.

Personally I would fit an isolator as have a call out bill for some one to disconnect the fan so there at lights at midnight is not funny. Yes I am sure you would just drop the supply cables but a tenant will not do that they will call out an electrician.

So yes in theroy no need for isolator but in practice yes there is.

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