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

 

[BrianDB9]

I was just wondering what type of HEPA filter should be installed on this bathroom fan ........................ I think it goes to show that there are too many people in the building industry with too much time on there hands when we need to worry about moving air about in a bathroom ..................

I've just done Bpec Ventilation course and see results of condensation and toxic mould quite regularly -by understanding ventilation properly you start to appreciate why "moving air " is essential.

I will never fit a switched fcu for ventilation to prevent people switching their air supply off.

To fit ventilation in new build now requires Bpec training and commissioning to prove it works.

Part F and the domestic ventilation compliance guide are areal good read too !

 

[sbelec]

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.

But then you have broken the live to the switch if the fuse blows and that negates the discrimination between light and fan which is what the idea of the isolator is, to give discrimination between the fan and light for maintainance purposes.
Hence my issue with the instruction manual. Manrose suggested I speak to an electrician and then ignored further questions.

 

[sbelec]

I've just done Bpec Ventilation course and see results of condensation and toxic mould quite regularly -by understanding ventilation properly you start to appreciate why "moving air " is essential.

I will never fit a switched fcu for ventilation to prevent people switching their air supply off.

To fit ventilation in new build now requires Bpec training and commissioning to prove it works.

Part F and the domestic ventilation compliance guide are areal good read too !

From experience in hotels that is what the isolator is for!!!!! When the fan is noisy.....

 

[plugsandsparks]

But then you have broken the live to the switch if the fuse blows and that negates the discrimination between light and fan which is what the idea of the isolator is, to give discrimination between the fan and light for maintainance purposes.
Hence my issue with the instruction manual. Manrose suggested I speak to an electrician and then ignored further questions.

Tell me about it, that was straight from Primeline destructions, needless to say i took it into consideration

 

[D Skelton]

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!! ​

I'm not saying you're wrong, but if you're right I really need to get on the phone to niglon! lol

 

[Darkwood]

FCU outside bathroom to cover feed to light switch, triple pole isolator next to fan.... if the fan developes a fault and takes the fuse out your house tenant/owner can switch the fan off and then replace the fuse to get the bathroom/toilet light back on, this is isolation to avoid a loss of lighting, given the situe where they couldn't get the light because they could not isolate fan individually then most joe public would run a 230v extension and table lamp into the bathroom not a stuation that wants to be premoted because of poor design.

 

[D Skelton]

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.

The electricians guide to the building regs does what it says on the tin mate, it is nothing but a guide and is fraught with red herrings throughout. I think you need to read through the whole thread as I have given quite a detailed explanation as to how this guide is often misinterpreted for regulation. Fitting a readily accessible means of switching off, or as some numpties like to call it 'local isolation' (which it isn't in any way [and that's an argument for another day]) has got nothing to do with whether or not the room is going to be dark without a window!

This leads me to my real grrrh, some 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?

You may not need to fuse down two line conductors as the bathroom may not need timer over run with the fan, the bathroom might not even require a fan at all and you can always choose a fan from many manufacturers that don't require it to be fused down. Alternatively, use a fan with an integral switch. Again, read through the whole post/thread again. Another thing to think about is if it is a new build or structural changes have been made and you install an isolator so your customer can just switch off the fan when you're gone, how does your install comply with Part F? Fuse the circuit down however so if you want to turn the fan off you've got no light, the customer won't switch it off. This isn't neccessarily how I would do it every time but it is worth bearing in mind. Each situation is different and should be treated as such, yes there are times where fitting a three pole isolator is going to be the best option but the point I am trying to make is that there is no black and white regulation regarding fans and three pole isolation and those who bang on about how it needs to be installed 100% of the time are just showing their lack of knowledge and lack of experience.

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.

Nope, nothing at all like control wiring, for a start the switched line alone will power the fan, take the permanent line out at the fan and you'll just lose your over run.

 

[sbelec]

Accept what you say, but any action in court where guides (building regs are law) and BS7671 (also a guide) are not taken into account you lose - unless you have very good documented evidence that what you have fitted is better. It comes down to the phrase complying with BS7671 and the guides are "likely" to show consideration to the Electricity at Work acts and Health and Safety Acts including risk assessment.
Used to be involved in design, construction and installation of plants and even 20 years ago I was challenged by HSE to show the assessment I had carried out was in line with the manufacturers recommendations and BS7671 and where it was not clear in either document that it was "the best solution" having assessed various options. My daughter who is a legally trained housing officer looks to written standard evidence of compliance to regs through best paractice guides so if I left out the isolator and somebody said it should have one then I would have to show that custom suggested it could be omitted and the guide would be accepted.
My Elecsa membership requires me to have available the appropriate guides and I have been asked to show compliance.

So all I say is ignore guides including BS7671 at your peril and an example of that is the guy in prison who did not fit cables in zones and who through not testing properly a young lady was killed. The fact that testing could have been carried out before the nail went through the cable was ignored. (the actual incident was pre 17th edition and rcd's were not required on immersian heater cables buried in the wall).

 

[D Skelton]

Accept what you say, but any action in court where guides (building regs are law) and BS7671 (also a guide) are not taken into account you lose

So all I say is ignore guides including BS7671 at your peril

BS7671 is not a guide, it is a non statutory set of regulations and classing that and other guides as one and the same is ridiculous. If you like guides so much why don't you have a read of David Cockburns guides!

 

[Engineer54]

View attachment 17368View attachment 17369

I'm not saying you're wrong, but if you're right I really need to get on the phone to niglon! lol

Unless things have changed in the not too distant past, perhaps you should!! lol!!
I've also only ever seen time/current curves for 3A and 13A fuses!! Perhaps things have changed on the fuse current rating side of things, but not as far as 1362 fuses being designed for appliance protection!!

If an appliance NEEDS protection, then the manufacturer should be supplying/incorporating a suitable means of protection. Not rely on the installer to provide it within the building wiring installation!!