Bathroom extractor fans

[Bridgemegger]

OK, I’m sort of qualified – time served on the 14[SUP]th[/SUP] edition, then left the trade in 1973 – kept my hand in for a few years….. I’ve recently moved into a house which has a lash up of an electrical installation, and I’m tackling one thing at a time. I’m armed with a copy of the 16[SUP]th[/SUP] edition of the regs and Brian Scaddens guide to 17[SUP]th[/SUP] edition. I have a megger (albeit 500v), Earth Loop Impedance tester and RCD tester (not that I’ve got an RCD to test yet!) It’s a bit of a nostalgia trip actually, as the house was wired in the mid 60s, when I was in the trade - brown Crabtree toggle switches, buckle clips, etc. The original installation is good (but dated), it’s the DIY lash-ups, that are the problem (and the mice), which is often the case.

I have 3x bathroom extractor fans – the small ceiling mounted ones ducted outside – and, in keeping with many of the DIY add ons, they’re lashed up with flex. They come on when the light/s are switched on.

I can work out the zones etc – what’s allowed where and what isn’t, and gradually making sense of ‘IP’s’. I’m a little bamboozled as to what switching/protective method is required for these fans.

Do these fans need a fused spur, fusing down to 3A, or less? At the moment they are simply wired into the light circuit – presently protected by a 5 amp rewireable fuse (I know I need to address this, and the lack of RCD protection).

I’ve seen 3 pole (me no understand) fan isolators? What 3 poles are they talking about?

Any guidance on this would be appreciated.

Tony

 

[Billynm]

A 3 pole fan isolator is to isolate the fan supply: live, neutral & switched live (if fan has an over run timer).

 

[RyanCheetham]

Fans are normally wired from the lights so that it runs while the room is in use. The 3 poles are Pern Live, Switch Live and Neutral. The perm live is for fans with built in timer for over run. The isolators should always be fitted to a fan

 

[BigTom83]

You take a permanent live, switched live, neutral & earth from the light ceiling rose to the 3 pole isolator (perm live, switch live, neutral) and then onto the fan. The fan will start when the light comes on (using switched live) and then run on fit x mins after light goes out ( using perm live). Hope this makes it clearer.

 

[Octopus]

If the manufactures instructions say fuse down to 3A then that is what you should do.

 

[applemac]

about time they made a fan with a built in fuse holder! some fans state in the instructions that 5-6 amp light supply ok but most say fuse down.
i think a isolator may be only required if the room has no window, assuming repairs to fan are in the day time...

- - - Updated - - -

about time they made a fan with a built in fuse holder! some fans state in the instructions that 5-6 amp light supply ok but most say fuse down.
i think a isolator may be only required if the room has no window, assuming repairs to fan are in the day time...

 

[Octopus]

about time they made a fan with a built in fuse holder! some fans state in the instructions that 5-6 amp light supply ok but most say fuse down.
i think a isolator may be only required if the room has no window, assuming repairs to fan are in the day time...

- - - Updated - - -

about time they made a fan with a built in fuse holder! some fans state in the instructions that 5-6 amp light supply ok but most say fuse down.
i think a isolator may be only required if the room has no window, assuming repairs to fan are in the day time...

More and more manufacturers instructions are stating isolation required.

 

[applemac]

ive fitted a fan new fan in my gaff this weekend sixth one in six years! seem a bit limp to me takes age to pull any steam out the shower/bathroom....
tempted to buy one of the turbo in line monster fans..

 

[nickblake]

this is what you need, it only states to fuse the perm live , this is due to the fact that when the perm live is not present the electronics in the timer circuit have disabled the switched side from the circuit the three pole isolator is so that the fan can be isolated for maintainance and replacement

 

[Bridgemegger]

this is what you need, it only states to fuse the perm live , this is due to the fact that when the perm live is not present the electronics in the timer circuit have disabled the switched side from the circuit the three pole isolator is so that the fan can be isolated for maintainance and replacementView attachment 15478

Thanks everyone!

Finding my way around the forum - I notice this bathroom extractor fan issue is quite a 'can of worms'! No wonder I've been mystified - I don't feel so bad now!

This is an interesting fitting - I've never seen one in the flesh - any pointers as to where I can buy one? Or its exact name/manufacturer?

Thank you again

Tony

 

[SPARTYKUS]

As pointed out above the 3 pole thing was to cover rooms with no windows and the resulting issue of maintenance with no lights....


Therefore....

Common sense tells me you don't need (oh! Contentious!) a 3 pole fan isolator for every fan!

Discuss

 

[RyanCheetham]

Agreed you dont need the isolator for every situation however i always fit them as i see it as good practice

 

[Octopus]

Agreed you dont need the isolator for every situation however i always fit them as i see it as good practice

you do if the manufacturers instructions say you should fit them.

 

[ashrow]

Isolators, Isolators everywhere
I prefer a local isolator for each fan (that way i get to turn it off when i dont want it to work ie loo breaks hehehe)
Seriously i do use a isolator for every fan i install regardless of light in rooms but i install humidi fans to bath rooms and only timer fans to wc,s with no windows (and as a norm i find most clients turn the isolators off anyway )

 

[Taylortwocities]

This is an interesting fitting - I've never seen one in the flesh - any pointers as to where I can buy one? Or its exact name/manufacturer?

I think its a Scolmore Minigrid. Maybe Nick can spill the beans??

 

[SPARTYKUS]

you do if the manufacturers instructions say you should fit them.

Good point Murdoch manu instrs rule.

However my common sense tells me its not necessary most of the time

 

[AIM]

Just a thought. How do you SAFELY isolate for maintenance etc..., without an isolator?

 

[SPARTYKUS]

Turn the MCB off at the fusebox that serves it might work

 

[SPARTYKUS]

Ps and that would be the same effect as switching off the single pole FCU i think you could reasonably fit in many cases (unless manufacturers instructions say otherwise)

 

[AIM]

Well done. So in a fault situation the punter has no lights until the faulty fan is changed.