Bathroom extractor fans and 3 pole isolation: A source of much controversy

[telectrix]

Sorry wrong thread had 2 open and posted on the wrong one:19:

we all make mistakes, as the hedgehog said, dismounting from the bog brush.

 

[Mega Greg]

As far as I understand it, the main purpose of the Building Regs and the electrically related British Standards is to increase structural and electrical safety. In the case of a bathroom fan, how does it help to put a 'local switch' for the fan in another room, potentially weakening the fabric of the wall and complicating the switching arangement. My first reaction to this topic was that it would be easier and safer for everyone to leave the switch function for the fan to the breaker box alone?

But then I got round to chapter 34 of the regs, the topic of maintainability and the issue of mechanical safety.

341.1 An assessment shall be made of the frequency and quality of maintenance the installation can reasonably be expected to receive during its intended life. The person or body responsible for the operation and/or maintenance of the installation shall be consulted. Those characteristics are to be taken into account in applying the requirements of Parts 4 to 7 so that, having regard to the quality of the maintenance expected:

It may be interpreted that the designer of an electrical system would be obliged to consult with the client to find out if the extra local switch is required and whether the client wants articial light to assist in jobs such as cleaning.

There's the case of the guy at college who's getting through the course supported by his cleaning job. His case may differ from say the average home owner doing maintenance.

Before I got into electrics properly, if I were a job like changing a light fitting, I wouldn't tend to trust the local switch but would switch off at the breaker. This worked for me as it was my house and could do what I wanted.

But what of my mate the cleaner. I don't think that he's bought a lock off device yet. There's no way he could ensure that the fan would not have spun, keys for safety measures not being in his control.

However, wanting to do a thorough job of the polishing he might require the clear visiblity of his work area as he buffed the appliance to a high shine.

Then, if his boss might return, stumble in the dark to the breaker box and reconcect the circuit while my college mate was getting stuck in.

Appologies for this AC complication.

Cleaning with water could still require the installation of a three pole switch for fan with a time delay function and, even if a fan were IP rated to make it impossible for maintenance types to get electricuted, the installation of a one way switch might cause confusion if other maintanence functions were undertaken.

I know this thread was intended to clear up this topic. It may be down to our Jack of all friend to add a extra touch.

(not having seen previous posts I don't know if this issue hasn't already been tackled).

 

[StewartElectric]

Agreee with this post

 

[amlu]

on last couple of bathrooms installed fan isolators right next to light switch. easy to wire, customer got a option of easily disabling the fan when they want go have a quiet session in the bath.

 

[Engineer54]

A bathroom timer fan with overrun that runs off a light that is fused down to 1A via a switched fused connection unit as per manufacturers instructions,

As far as i'm aware the BS covering these fuses do not recognise any other fuse rating other than 3A and 13A!! Other ratings that are available, do not and should not include the BS 1362 number!! The other point being, that the same BS does not include protection of appliances, only conductors!! So this is one manufactures instructions you don't comply with!! lol!! ​

 

[valleybilly]

Manufacturers installation instructions take precedent over ( non statutory BS 7671 ) regardless , eg replacement shower needing rcd protection is not like for like if it has not got it even if its the same kw . Your only get out is if they state ( recommended ) but usually they state , must ' in bold writing . page 21 reg 134.1.1

 

[sbelec]

The IEE Electricians Guide to the Building Regs states:
"An extractor fan supplied from a lighting circuit for a bathroom without a window should have its own means of isolation, otherwise replacement or maintainence of the fan would have to be carried out in the dark. A fan with an automatic run on should be fitted with a triple pole isolator which must be fitted outside zones".
Whilst I agree with the posts completely, not fitting an isolator in these circumstances where someone was hurt or killed because they hadn't disconnected the supply because it was dark or fell off the ladder in the dark would potentially be liable as they had not carried out the appropriate risk assessment on design. The fact that it is in writing from the IEE would compound the issue.

This leads me to my real grrrh, most fan manufacturers require a fuse in circuit and then talk about the lighting circuit switch live and a permanent live for the fan run on. How do you wire up a single pole fuse into 2 live supplies but still leave a situation where the fuse is not in the light part of the circuit? Something I have mentioned before and today replaced a fan where the electrical company had run the permanent live through the fuse but not the switched supply. I suppose this is the best of both, the switched live is only energising electronics to start the fan and not necessarily supplying the power to drive the fan in almost the same was as low voltage control wiring and contactor energising 3 phase motor supplies.

Amlu - how do you get your nuetral? I have not installed a bathroom switch except pull cord for a long time, with zones and tiles the ceiling is easier.

 

[plugsandsparks]

Its barking i know, basically you have to intercept the perm live going to the switch and into a FCU, that way you isolate both perm and switched at the same time. Then put the lot through a 3 pole isolater for maintenance.

 

[amlu]

Amlu - how do you get your nuetral? I have not installed a bathroom switch except pull cord for a long time, with zones and tiles the ceiling is easier.

I`m running neutral to the switch
There will be 2 single boxes linked together with bit of conduit, feed coming in, feed going out, bathroom light out, 3-core fan out.

 

[valleybilly]

Fit Inline fuses within the unit , Maplins £1 ' last 1 i did required 1amp fuses ! , they should be pre installed IMO