Fan Isolation

[davetheglitz]

I've always accepted that all ventilation fans should be able to be isolated. However my client insists that he doesn't want an isolator as tenants tend to switch off the isolator and the resultant condensation damage causes no end of damage.

He is paying, I understand what he is getting at, and I can't see any harm in omitting an isolator.

I've been searching the regs to find out why an isolator is needed for a very small fan and came up with a blank. Does anyone know any different?

 

[SPECIAL LOCATION]

Last sentence of 134.1.1 page 19.

Manufactures instructions et-al...

99.9% of manufactures instructions say some form of Isolating switch and/or a 3amp fuse.

132.15.1 Isolation and switching. page 18

effective means of isolation, suitably placed for:-

Installations, and every Circuit and from all equipment.

What about Non-switched fused spur?

Security Fishtail key switch?

Contactor from remote isolator not accessible to tenants?

:|

 

[wozz]

what about fusing down the supply to the bathroom lights with a switched fused spur in the loft (if there is one), fans fused down, remote lockable isolation, tennants arnt likely to get in loft to isolate their fan and light.

any problems with this set up?

 

[davetheglitz]

what about fusing down the supply to the bathroom lights with a switched fused spur in the loft (if there is one), fans fused down, remote lockable isolation, tennants arnt likely to get in loft to isolate their fan and light.any problems with this set up?

Hi Wozz/Special - I'm playing devils advocate on this - but I'm trying to get to the bottom of this. The Customer wants fan with timer from lights - so switched fused spur in loft doesn't help and obviously 3A max goes out of the window unless you fit 3A fused spur for both the live and switched live supplies - doesn't seem practical to me.

You could always fit an isolator in the loft - but thats just a catch all to say you've covered the perceived regs. The average punter isn't going to know that it's there - so why fit it?

I'm just trying to think outside the box - the rotating machinery hazard with one of these fans is negligible - so do we need to isolate a fan if a customer specifically requests otherwise?

Isn't switching off the lighting MCB sufficient isolation for maintenance? It's no different to a loop in ceiling rose.

Would you lose a rewire for this on point of principle?

Just trying to get my thoughts together!

Thanks

Dave

 

[wozz]

fuse down the feed to the bathroom, after that the supply gets divided in to perm and SL at the fitting / swtich.

I think strictly speaking you dont need a isolator, but you will need to fuse the supply down, as all fan instructions i have seen require this.

 

[davetheglitz]

fuse down the feed to the bathroom, after that the supply gets divided in to perm and SL at the fitting / swtich.I think strictly speaking you dont need a isolator, but you will need to fuse the supply down, as all fan instructions i have seen require this.

Nice thought - particularly if RCD for bathroom supplies is required.

 

[SPECIAL LOCATION]

Personally I always fit an isolator and fuse!

no if's no buts just quote and fit the bu99ers!

never had any problems.

other points to consider are

Has the room got windows? i.e. natural light coming in such that at times you may not need to turn the lights on?

If yes what about a ceiling mounted pir sensor (use the timer off the sensor to supply a bog standard Non-timer fan)

Put a non switched spur from perm live @ lights to PIR sensor.

So if fuse out ALL supply to PIR & thus fan is dead ?:|

Sell it to the landlord that the fan will always come on whenever someone goes in the room!

 

[the doctor]

hi

you could ditch the fan switch, loop directly off the lighting and declare the mcb, main switch as your isolator:coat

bearing in mind, most fan isolators are not isolators- an isolator has to be " lockable offable"

pulling hard hat on now.....

 

[a1]

"Lockable Offable" - Nice words are those, Doc.

 

[Andy™]

hiyou could ditch the fan switch, loop directly off the lighting and declare the mcb, main switch as your isolator:coat

bearing in mind, most fan isolators are not isolators- an isolator has to be " lockable offable"

pulling hard hat on now.....

some fan isolators do have a locking facility. there are pin holes at either end, and a seperate device locks onto it. MK are like this (or they used to be0

 

[maccarooni]

hi dave

when wiring bathrooms on rental properties, As per landlords instructions...I generally pull the feed to the 3 pole isolator switch first. This way, if they turn off the isolator, they lose the lights.....

Time to duck.....

 

[Riggy]

Forget the isolator, if someone loses arm whilst maintaining the fan I am happy to take responsibility!

Complying with the regs is no substitute for common sense.

 

[PC Electrics]

I've recently installed a flush ceiling pir to control a standard fan. that way the fan comes on whenever anyone comes into the room irrespective of whether they turn on the light or shower or not. As it's a standard fan and all on the lights circuit no need for an additional isolator.

My understanding was you only needed the extra isolator for timer fans with a perm live to them??

If you're using an in line fan, just fit the isolator next to the fan in the loft? And as suggested wire the lights through it too.

 

[Lurch]

As it's a standard fan and all on the lights circuit no need for an additional isolator.My understanding was you only needed the extra isolator for timer fans with a perm live to them??

Wrong.

If you're using an in line fan, just fit the isolator next to the fan in the loft?

That's what you should do, if you fit an inline fan in the loft the isolator should be by the device it's isolating, not somewhere else such as on the landing wall. (Assuming you use a standard fan isolator switch and a lockable one).

 

[PC Electrics]

I always fit an isolator and have never been asked not to. But can you say why that understanding was wrong?

 

[Lurch]

But can you say why that understanding was wrong?

Erm, not at the moment. There'll be a line in BS7671 somewhere, the latest edition of which I don't currently possess.

 

[Apache]

Erm, not at the moment. There'll be a line in BS7671 somewhere, the latest edition of which I don't currently possess.

Seems a little tenuous!

I can quote regs from books I don't own - but it means nothing.

Do remember this is a nice forum!

 

[Lurch]

Seems a little tenuous! I can quote regs from books I don't own - but it means nothing.

So could I once.

132.15.2, 537.3.1.1, 537.5.1.3?

 

[wozz]

this more to do with what the fan instructions say than the regs in my opinion.

 

[Andy™]

but do you have to follow manufacturers instructions? after all, you dont have to follow 7671, you can deviate from it providing its safe etc. surely the same applies to manufacturers instructions