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

[D Skelton]

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!!

Agreed!

 

[sbelec]

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!

Non statutory means simply that, it is not on the statute books as law, you cannot be prosecuted under it however you can be prosecuted under HSE Acts which are law who may quote BSI and IEE literature as safe, standard technical parctice.
Just like you cannot assume that complying with BS7671 will make you immune to prosecution, HSE quote from BS7671 states that "compliance with BS7671 is LIKELY to comply with the relevant statutory instruments". It does not say guaranteed.....

Following on from this, publications and guidance from the IEE on BS7671 could similarly be quoted simply because they are deemed as an authoritive voice. As an expert witness anyone with the "technical experience" could be called to Court and give testimony either in support of non-statutory documents or to disprove its content as poor based on their own research. Very difficult when up against major documents but not impossible, if you have the money.

As a footnote one of the documents Elecsa demand at their annual assessment is the On-Site guide! As well as BS7671, Part P and the Memorandum on Electricity at Work Regs.

 

[D Skelton]

Ok mate, whatever. There is no telling you coz no matter what anyone says you will still believe you're right. Still... You are wrong.

I maintain my point. There is a vast difference between a set of non-statutory regulations and a guide. You can't be prosecuted under EAWR for not following the on site guide can you!? A guide by it's very nature is a simpler way of explaining something more complex, a means of giving basic instruction (OED definition). It will guide you through those complexities with much easier to understand language. Well what is BS7671 guiding you through?

Again, if guides are the be all and end all then give one of David Cockburn's guides a read then come back and tell me that you're still right.

The HSE will not quote just 'any' IEE literature when prosecuting, they will use BS7671, that is all, because if you have followed BS7671 then you will have by definition followed the guidance to BS7671. If you follow the much watered down guidance however, then you may not have complied with BS7671.

Another thing worth pointing out is the fact that there are people within the highest circles at the IEE who still haven't got a foggyest what they are talking about when it comes to electrical installation so claiming that all of their literature is bomb proof is a load of rubbish in my opinion. Even BS7671 is full of mistakes and uneducated doctrine.

 

[gonefishing]

It would seem that whenever the topic of bathroom extractor fans comes up, triple pole isolation has always been a rather debated subject. There are those of you who talk about not having to fit an isolator if there's a window and there are those of you who say that an isolator should always be fitted. Well, I'm writing this today to see if I can help clear up this subject once and for all.

There is a common misconception that if a bathroom has a window, then an isolator does not need to be fitted as mechanical maintainence can take place whilst the work area is suitably lit with daylight. Unfortunately, this is not the case at all. Generally speaking (there are exceptions), an extractor fan does not need to be fitted in a bathroom containing an opening window at all providing it can be demonstrated that Part F (ventilation) of the building regs has been complied with. This is to do with the air change rate within the bathroom and has nothing at all to do with mechanical maintainence only being allowed when lit. The amount of lighting that should be provided whilst working is down to the Health And Safety at Work Act not BS 7671. There is also a common misconception that a 3 pole isolator switch must be installed to allow for the fan to be isolated, this is also not the case, points of which I will explain in detail later on.

I have also seen a lot of debate regarding which type of extractor fan has to be fitted. Whether it has to be a timer fan with overrun, humidity controlled or simply one that operates off of the switched live alone. This again is a topic that is down to Part F of the building regs, not any electrical regs that I know of. Whatever the air change rate that specific bathroom needs to conform to Part F, then a fan that is fitted must be able to provide it, regardless of the type of fan. This means it may have to be a timer fan with overrun, it also means it may not need to be, it all depends.

Another point worth noting is that Part F only applies to new builds and refurbishments. A rewire is not a refurbishment as no structural changes have been made to the property. This means that there is no requirement to fit an extraction fan during a rewire alone. A rewire during a loft conversion however would be classed as a refurbishment, this means an extractor fan would need to be fitted and it would need to comply with Part F. Finally, if a bathroom that isn't already fitted with an extractor fan complies with Part F, a new fan installation in that bathroom need not apply to Part F. This means that in this scenario, selection of the type of fan is free for the customer or installer to choose.

Now I come to a couple of regs, first of which is all of those covered by 537.3.1. Essentially, electrically powered equipment shall be provided with a means of switching off where mechanical maintainence may involve a risk of injury. I feel the need to stress that use of an MCB and/or main switch and/or RCD is a perfectly acceptable means of switching off a bathroom extractor fan for mechanical maintainence. Nowhere does it state in BS 7671 that switching off for mechanical maintainence must be provided locally.

Another regulation I will draw your attention to is 132.15.2 which states that 'Every fixed electric motor shall be provided with an efficient means of switching off, readily accessible, easily operated and so placed as to prevent danger'. This is a regulation often pointed to by people who are in the 'Always fit 3 pole isolation club'. Here, 'means of switching off' does not neccesarily mean isolation. An extractor fan that runs off the switched live alone could reasonably be expected to conform with this regulation by use of the light switch alone, thus not needing a 3 pole isolation switch . 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, could also reasonably be expected to conform with this regulation by use of the SFCU alone, thus not needing a 3 pole isolation switch. A third example I could give you is of an extractor fan with an integral switch, this would not need 3 pole isolation either. Ultimately, depending on your own interpretation of the words 'readily accessible', it could be argued that a bathroom extractor fan could be efficiently switched off with the applicable circuit's MCB depending on the placement and accessibility of the consumer unit.

Now of course, all manufacturers instructions for electrical equipment must be followed to comply with BS 7671 but taking into account all the above highlighted points, what I have demonstrated is that the debate surrounding extractor fans in bathrooms is never black or white. Although it may still be considered best practice, there is no requirement in BS 7671 to fit 3 pole isolation for extractor fans, however, they must be able to be switched off, and there must be some method of isolation for the purpose of mechanical maintainence.

I hope this clears up any future debate or confusion regarding bathroom extractor fans.

"Now I come to a couple of regs, first of which is all of those covered by 537.3.1. Essentially, electrically powered equipment shall be provided with a means of switching off where mechanical maintainence may involve a risk of injury. I feel the need to stress that use of an MCB and/or main switch and/or RCD is a perfectly acceptable means of switching off a bathroom extractor fan for mechanical maintainence. Nowhere does it state in BS 7671 that switching off for mechanical maintainence must be provided locally."

Just to disagree with you on a few points, have you forgotton that the original intention of the fan isolator switch was to disconnect all the poles (except CPC where used of course) the main concept is to be able to isolate the fan for maintenance. That's difficult to do if the MCB is used to control the circuit if it's dedicated, if it's for the lighting circuit then the regs say that no installation should be installed as to be a nuisance and switching the lighting MCB off in the dark is dangerous and impractical as the Neutral is still connected, isn't it? Also, any thought to the maximum amperage required by the fans. Most suppliers require a 3 amp fuse so that means a dedicated FCU as well. Anyone ever been called out because of a stalled fan?. Dispite what the regs say you must be sensible and provide a system that is well designed and in the interests of the customer, why do a second rate job. Install a FCU and an isolater, many fan companies will not credit a fan if it's burnt out. And while on the subject of fans has anyone had a problem with the Steeple range of fans, especially the humidistat controlled ones?

Read more: http://www.electriciansforums.net/e...on-source-much-controversy.html#ixzz2MZI9Yl5W

 

[D Skelton]

On a TN system disconnecting the line conductor only is a perfectly acceptable means of isolation. With regards to fuses, I thought I was pretty clear in my OP.

Read the last paragraph and then disagree with me again

 

[sbelec]

The 3 phase isolator, especially if fitted outside the bathroom might not be sufficient under Electricity at work regs. The requirement is to work dead and on a circuit verified as dead and locked off in a manner which will not allow inadvert switching on.
At the side of the fan, no problem but outside with the potential of the door the electrician cannot be in control of the safe means of isolation. I have never seen a fan isolator with a locking facility.

 

[D Skelton]

Exactly! Which is what makes this 'local isolation for mechanical maintenance' a load of nonsense. An MCB however can be locked off.

 

[Andy78]

The 3 phase isolator, especially if fitted outside the bathroom might not be sufficient under Electricity at work regs. The requirement is to work dead and on a circuit verified as dead and locked off in a manner which will not allow inadvert switching on.
At the side of the fan, no problem but outside with the potential of the door the electrician cannot be in control of the safe means of isolation. I have never seen a fan isolator with a locking facility.

MK fan isolators are lockable I know that for sure.

 

[D Skelton]

Guys I'm not going to be disparaging towards sparks who fit isolators, what I will do however is point out to those who say that they are a 'requirement' in 100% of cases that they are wrong!

Edit: And let's be honest, there are far more pressing matters at hand than whether we need to fit fan isolators. I just thought it would be a useful post, I never thought it would turn into such a debate!

 

[Andy78]

I'm not disagreeing with you for the record. Was just chipping in with a bit of product advice. :smile5: