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

[Stroppy]

 

[Estimator]

"If you follow the wiring logic above would that not do away with the need for the triple pole? Both feeds for the fan are through the fuse which can be removed and the fuse carrier locked open for safe isolation so regardless of location safe isolation is satisfied? "


I would think so...

Sorry I didn't read all your post, before posting again...

 

[gonefishing]

Find me some regulations then that prove me incorrect. If you can, I'll happy eat humble pie, until then why not keep your arrogant remarks to yourself.

And guess what, the beauty of non-statutory regulations is that they ARE often open to interpretation.

Arrogant? do you know what it means?
Aren't you the one that decided to give all of us the bennifit of your regs advice? the regs are minimum and they are are for interpretation but not for making installations less safe. You are attempting to give advice in a special area which could provide or give some readers incorrect advice. If the readers have to rely on this forum for knowledge you should be promoting safety and not scraping the regs for quick get outs. It is common practice to install an FCU to comply with the manufactures requirements for maximum fuse requirements, it does mention manufactures requirements several times in the regs doesn't it? and anyone not installing a 3 pole switch doesn't understand the RCD requirements. As I mentioned many here don't understand how to wire a BS 1362 fuse into a system let alone follow your " A source of much controversy" there's no controversy and safety is paramount not the regs.

 

[D Skelton]

Arrogant? do you know what it means?

Yes.

Aren't you the one that decided to give all of us the bennifit of your regs advice? the regs are minimum and they are are for interpretation but not for making installations less safe.

I'd like to know exactly how I've advocated making an installation 'less safe'? I think you need to read my OP again as all I have done is make the regs regarding this issue a little clearer and provided examples of possible interpretation. I made it CLEAR that it is often best practice to fit an isolator but that it was not, contrary to popular belief, an absolute requirement.

You are attempting to give advice in a special area which could provide or give some readers incorrect advice. If the readers have to rely on this forum for knowledge you should be promoting safety and not scraping the regs for quick get outs.

Special area?!? Do me a favour please! My advice is entirely accurate! The regs regarding isolation, electric motors, special locations and manufacturers instructions are plain to see in black and white! This might be a special area for you, for DIYers or for 5WWs but please don't come on here and insult me with your patronising implication that I somehow struggle to understand the regs when it comes to a bleeding bathroom fan! You don't even know what a specialist area is, I work in a number of specialist fields and believe me they are a little more complex than a bit of 3 core and a shaded pole!

It is common practice to install an FCU to comply with the manufactures requirements for maximum fuse requirements, it does mention manufactures requirements several times in the regs doesn't it?

Rubbish! I'd say it was common practice never to pick up, let alone open a set of manufacturers instructions!

and anyone not installing a 3 pole switch doesn't understand the RCD requirements.

Crap! Maybe I better go round every installation I've ever worked on and install 3 pole isolation to every item of equipment and every accessory that might at some point in the future need maintenance or changing! Clearly MCBs aren't up to the job any more!

As I mentioned many here don't understand how to wire a BS 1362 fuse into a system let alone follow your " A source of much controversy" there's no controversy and safety is paramount not the regs.

If there was no controversy then you wouldn't be arguing with me on this thread with your superior attitude and knowledge backed up purely by blind following of here say and bad advice.

 

[itselectric]

Switching an mcb off is not isolating, unless it's a double pole mcb. Therefore the fan or item of equipment being "ISOLATED" by an mcb, technically is not.

 

[D Skelton]

Switching an mcb off is not isolating, unless it's a double pole mcb. Therefore the fan or item of equipment being "ISOLATED" by an mcb, technically is not.

Do you own a regs book?! If so, you need to read it again!

 

[itselectric]

I own a regs book, I will read it and if I have interpreted it wrong I apologise. The books at work so will have to wait.

 

[sbelec]

Stroppy, what make is this? Never seen one before and not in my wholesaler, I do use on line and may have never picked this up being a small catch/ screw on the bottom.
Many thanks, one for the memory as there is so much manufactured it can be hard to spot the little difference. Maybe we should have a forum for "accessories and kit" as well as tools somewhere you can ask if anyone had seen an accessory for a specific job?


Quite ironic how complex something so simple can be - I would love to go back to commissioning PLC / MCC's far simpler than houses!

 

[Guest55]

Switching an mcb off is not isolating, unless it's a double pole mcb. Therefore the fan or item of equipment being "ISOLATED" by an mcb, technically is not.

since when does a domestic bathroom fan require D.P. isolation ?

and if you look at table 53.2 in the regs it says.........

" circuit breaker ....bs60898 .....Isolation - Yes
Emerg Switching - Yes
Functional Switching - Yes

seems like youve gulped a couple of cans of incorrect.

 

[itselectric]

Am I right in saying that both live and neutral are classed as live conductors, if so switching off means exactly that "switching" I am given to understand that isolation means completely removing the appliance from the circuit.
I am not involving myelf in the bathroom fan saga. just the term isolation.

 

[Estimator]

I’m not taking a “side” in this rather heated discussion, feeling that, as with a lot of the content in the BGB, isolation is left rather open to interpretation, by different people.

Here are a few extracts from various manufacturers installation leaflets. Apologies if the images don't turn out quite right, it's my first attempt at this...

Greenwood Airvac – Unity CV100



Greenwood Airvac – EL100, EL150U, EL150 & EL150SCPC



Vent Axia

Manrose

Xpelair




Out of the 4 manufacturers only one mentions a 3 Pole isolator and this is in addition to the suitably fused connection unit, which are all double pole. I think, if you lock the fuse carrier open, then it would be unlikely that some one would switch the spur on, maybe causing you a problem with the RCD, if you are changing the fan.

On the same subject, by my user name you can tell I'm primarily, nowadays an estimator, but I am time served and had a break from office work for a while, a few years ago and “went back on the tools”. I price a lot of jobs, mostly commercial with some apartment blocks and a lot feature extract fans fed from local lighting circuits and it’s 50/50 on whether a FCU or both a FCU and fan isolator is required. Most of the jobs are pre-designed by "experts"

 

[Estimator]

since when does a domestic bathroom fan require D.P. isolation ?

Since the manufacturers say it should?

But only if the circuit protective device is bigger than 5A? Sorry that's separate fusing...

see my previous post...

I'm not saying you need DP isolation, just what the manufacturers say...

 

[Stroppy]

Stroppy, what make is this? Never seen one before and not in my wholesaler, I do use on line and may have never picked this up being a small catch/ screw on the bottom."

This one is a Newlec, and from my google search for the phrase "triple pole isolator with lock" it seems MK do one as well. They come with a little key to operate the locking device, which I imagine disappears without trace after 10 minutes of the installer leaving the building

 

[supertoad]

a fan on a timer needs a permenant feed/sw feed/neutral, i recon that the hse would require safe isolation[ie; not working in the dark, with half the lights in the house off, and a torch in your mouth-the "regs"are a BS standard and the hse requirments tend to be legaly binding-i think

 

[HandySparks]

i recon that the hse would require safe isolation[ie; not working in the dark, with half the lights in the house off, and a torch in your mouth

So what do you use for illumination when you're working on a lighting circuit?

(Not saying that being able to leave the lights on isn't convenient.)