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

[Silly Sausage]

MK fan isolators are lockable I know that for sure.

True, got one at home.
Seem pretty crappy though, Two tiny plastic pins to lock the switch off.

 

[Andy78]

True, got one at home.
Seem pretty crappy though, Two tiny plastic pins to lock the switch off.

True, but if someone is going to make efforts to turn it on by breaking those pins, and ignoring the huge red flappy thing with a padlock dangling off it, then no amount of safeguarding and locking off is going to protect you from that person.

 

[Silly Sausage]

True! But remember, the world is full of idiots!

 

[Estimator]

On the legal standing of the BGB, I’m not a lawyer, but the Building Regulations are law, which everyone agrees on, and the approved documents give guidance on complying with them.

The following is an extract from Approved Document Part P 2013 Edition, Section 1 Design and Installation (Page 3)
“General
1.1 Electrical installations should be designed and installed in accordance with BS7671:2008 incorporating Amendment No.1:2011.”
So does mean that the BGB, is in a roundabout way, law?

Going back to the thread subject bathroom fans, fuses and isolators.

Change the pull switch controlling the lights to a DP pull switch (MK and Crabtree do them), connect the lighting feed and sw/wire to one pole.

From the lighting circuit take a Live and Neutral to a Fused Spur (fused to 3A).

Then run a twin from the spare pole of the pull switch to the spur.

Run a 3c to the fan.

Connect the lives from the 3c and the twin to the switch into the Load of the spur.

Joint the sw/wires from the twin and 3c in a Wago in the back of the Spur box.

If you really want to install a 3 pole isolator, run 2 twins and the 3c to it and make the connections there.

Both lives fused and isolated...

 

[D Skelton]

So does mean that the BGB, is in a roundabout way, law?

Technically no, but it sure as hell aint a guide!

 

[gonefishing]

Sorry, can't agree with any of that last paragraph or not...you are saying that no isolation is required close to the fan and then that no 3 pole device is required for isolation. Ever tried changing a fan on RCD protected circuit? you are really saying that you can remove all the connections, in most cases with permanent live and switched without causing the RCD to trip? TN system or not who takes the chance? Just because you interpret the regs your way doesn't make it correct does it?

I awlays fit a FCU fused to manufactures requirements and a 3 pole isolator and always 3+cpc cable and all accesible (usually above doorway).
I really can't believe some of the comments here concerning providing BS fuses protection to both permanent live and switched live, I would consider that wiring knowledge as 1st year stuff...

 

[D Skelton]

you are saying that no isolation is required close to the fan and then that no 3 pole device is required for isolation.

Just because you interpret the regs your way doesn't make it correct does it?

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.

 

[i=p/u]

Yeah do what you do , but I install them beside it or above 2.2m

 

[sbelec]

I really can't believe some of the comments here concerning providing BS fuses protection to both permanent live and switched live, I would consider that wiring knowledge as 1st year stuff...

Not sure if I have misunderstood your quote, so appologies before i get shouted at, manrose fans installation wiring diagram show an FCU with a live split, 1 to light switch for switching and one direct to the fan as permanent live.
What puzzled me and this has now been answered within this thread was the small DP pull cord, one for fan switch live and one for light switch live. Haven't seen one for years and certainly my usual supplier said he had never seen one for years only the big shower switch.

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?

That will be my preferred route from now on, so now to shout at my supplier as I want DP 6 amp pull cord light switches.

Thank you Mr Skelton, for all we have had our disagreements the discussion you started has at least give me a standard which I am happy with and which has puzzled me for months if only it hadn't taken so long! The last fan wiring diagram would never have worked and all statute says that manufacturers instructions should be complied with - and that p!sses me off.
As a footnote, including myself, sometimes when writing briefly not all the meaning comes across. I know what I want to say but sometimes when I read back not even I understand it!

 

[Estimator]

To answer gonefishings' post #56 In my last post #54 I wasn't saying install or not install a 3 pole isolator, I mean't, it's up to your interpretation of the regulations whether to install one or not. All I was offering was a solution to the problem of fusing the Switch feed to the fan.

If you're changing the fan on a RCD protected circuit and it's wired through a Spur as my original post and the spur is switched off then then the neutral to the fan is isolated.

The DP Pull Switch is 16A, MK3151WHI or Crabtree 2163 or Legrand 061130

Discount-electrical.co.uk sell the MK

 

[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.)

 

[BrianDB9]

Freaking heck i'm gonna get my hard hat on ! Thought it was a forum not a boxing ring lol

Just had an issue about ventilation fans in bathrooms and looks like my solution is going to be to fit a DP secret key switch with fuse on a grid switch with the faceplate engraved "Bathroom Ventilation" it's going to be located in the adjacent store cupboard and wired onto the lighting circuit so tenants are disuaded from turning the CB off.
The fan has humidistat and pull cord overide so no issues with over run.

 

[supertoad]

not telling! but good point,[its the desighn that bothers me]-think i mey have mispelt desighn

 

[Guest55]

my solution is going to be to fit a DP secret key switch with fuse on a grid switch with the faceplate engraved "Bathroom Ventilation"

excellent idea imo , thumbs up

 

[Stroppy]

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

Head torch.

Or work live so you can leave a light on.

 

[ontimeelectics]

Great info. Copied and pasted into my archive file.

 

[kenai36]

Great post thank you very much! I'm about to fit one for a customer in a ceiling and was wondering where the hell to put a three pole isolator.

 

[telectrix]

sod all this fan crap. open the window and fart. steam and methane mix and blow out the window. sorted.

 

[Jeffmo65]

This is a tangent of this subject . Has anyone managed to wire a Vort Quadro micro 100 fan that has actually worked . Checked checked and checked again my wiring and all is as it should be . Power at fan wen isolator switched , switched line atfa when light pull err pulled . Brand new out of box . Diagrams are a bit weird aswell

 

[Richard Burns]

They look straightforward for wiring, neutral to neutral, permanent line to line, switched line to 3, connect 4 and 6 for high speed or 5 and 6 for low speed; unless you have seven terminals and a capacitor in which case 4 or 5 are connected to permanent line.

 

[wozz]

Freaking heck i'm gonna get my hard hat on ! Thought it was a forum not a boxing ring lol

Just had an issue about ventilation fans in bathrooms and looks like my solution is going to be to fit a DP secret key switch with fuse on a grid switch with the faceplate engraved "Bathroom Ventilation" it's going to be located in the adjacent store cupboard and wired onto the lighting circuit so tenants are disuaded from turning the CB off.
The fan has humidistat and pull cord overide so no issues with over run.

Not trawling though the rest of this but the solution above does not meet the requirements of a isolator.

 

[Dan]

Just bumping some threads in the Electrical Wiring Theories and Regulations forum category here on our Electricians Forums. If this specific topic isn't current, just ignore it, it'll drop off the list in no time. However, if it's something you'd like to contribute to, feel free to reply and bring it back into current discussion.