Is a Fan isolator required

[John robertson]

Hi guys you've likely had this asked a lot on here. I have been asked to fit a extract fan wi timer in a bathroom for a friend, i have told him he should get a fan isolator but is adamant he does not want one for some reason (for all it would cost). Is it still ok and safe for it to come on with the light?

 

[MFS Electrical]

Hi guys you've likely had this asked a lot on here. I have been asked to fit a extract fan wi timer in a bathroom for a friend, i have told him he should get a fan isolator but is adamant he does not want one for some reason (for all it would cost). Is it still ok and safe for it to come on with the light?

The fan should have a triple pole isolator as it’s a timer fan to be able to isolate for mechanical maintenance (taking off the cover and cleaning it) it would also contravene building regs here in Scotland so my gut instinct would be talk him into it or walk away...

 

[Gavin John Hyde]

Does approved document f apply in scotland?
Down here it covers the airflow rates required when fitting to an existing building then you must not leave it any worse than it was before hand.

 

[Loki]

Bet the manufacturer instructions say to have an isolation switch fitted.

 

[buzzlightyear]

Bet the manufacturer instructions say to have an isolation switch fitted

some do ,and some don't .

 

[Octopus]

So we follow BS 7671 in existing properties for maintenance ...... Part F isn't relevant

BS 7671 says nothing on the subject if my memory serves me correctly..

 

[robd]

Can you put one in the loft I often do this with inline fans for example next to the unit.

 

[Wilko]

Hi - I plan on fitting a local means of isolation for fixed appliances. This is often in the manufacturer's installation instruction as @Loki has mentioned. This is one for a common bathroom fan I've used .

 

[Dillb]

A MCB or fuse will act as isolation too. The only reason local isolation maybe required would be so the light stays on while carrying out any maintenace on it.

 

[telectrix]

A MCB or fuse will act as isolation too. The only reason local isolation maybe required would be so the light stays on while carrying out any maintenace on it.

think that requirement came out when we had candles fitted to out hard hats rather than head torches.

 

[MDJ]

Nice to have an isolator though, especially if the fan fails and it is winter. If you turn the circuit off without one and the torch has no batteries it is a hard job to change one lol

 

[Octopus]

Nice to have an isolator though, especially if the fan fails and it is winter. If you turn the circuit off without one and the torch has no batteries it is a hard job to change one lol

Most people have mobile phones with torches ..................

 

[Dave OCD]

Why do some forum members argue so fiercely against common sense when something isn't strictly required by BS7671, bear in mind this is the minimum standard that we have to conform with.

 

[Dillb]

No ones arguing, just stating different points and how it can be resolved in different ways. Theres no hard and fast rule for a local isolator, so much like BS7671 its open to interpretation.

 

[Andy78]

Why do some forum members argue so fiercely against common sense when something isn't strictly required by BS7671, bear in mind this is the minimum standard that we have to conform with.

The question asked was "is one required ?"
The question is only being answered truthfully and accurately. If it's a question of requirements then the minimum standards are relevant.

If the question was "is it best to have one ?" then answers might have been different.

 

[telectrix]

Most people have mobile phones with torches ..................

tried that. the phone kept falling off my head.

 

[Wilko]

tried that. the phone kept falling off my head.

Not really our thing, but he does bear a resemblance to a Forum member

 

[westward10]

Who?

 

[telectrix]

Doctor.

 

[driverman]

As many on here will know MI require a 3 amp fuse also on most models

 

[Dillb]

As many on here will know MI require a 3 amp fuse also on most models

Have you ever come across one fail because it wasn’t?

 

[123]

Use a decent brand like Vortice and there is no need for the 3A fuse. Silliest thing I have seen is Bathroom Lights Fused down from 5A fuse/6A MCB to 3A fuse for the fan. Totally pointless exercise.

 

[brianmoooore]

I know of a fire in a new build a few years ago, where the fire was deemed to have been caused by stuck fan blades and the lack of a 3A fuse in the fan supply. Locked rotor current insufficient to trip the 6A MCB supplying the circuit.

 

[telectrix]

I know of a fire in a new build a few years ago, where the fire was deemed to have been caused by stuck fan blades and the lack of a 3A fuse in the fan supply. Locked rotor current insufficient to trip the 6A MCB supplying the circuit.

it would probably not have blown a 3A fuse either.

 

[brianmoooore]

I would think that is exactly the reason the manufacturers specify a 3A fuse.

 

[telectrix]

they specify a 3A fuse because they don't have a clue about OCPD discrimination. a 1A fuse would be more appropriate.

i'll give you a personal example. i had a vivarium with a 250wall heat/light reflector lamp. plug fuse was 5A. when the lamp blew, it took out the 16A MCB in the CU, leaving the 5A fuse in the plug intact.

 

[brianmoooore]

Presumably the collapsing filament produced a near short circuit, otherwise nothing would have blown/tripped. Under those circumstances a type B MCB probably would trip faster than a plug fuse would rupture. The stuck fan motor would pass a sustained current of a few amps which is a completely different scenario.
On a related subject, there have been many threads on here concerning MCBs in series, and their lack of discrimination. While this may be true when short circuits are considered, a lower rated second MCB in the chain will discriminate against overload.

 

[telectrix]

we hope.

 

[davesparks]

I know of a fire in a new build a few years ago, where the fire was deemed to have been caused by stuck fan blades and the lack of a 3A fuse in the fan supply. Locked rotor current insufficient to trip the 6A MCB supplying the circuit.

Then the manufacturer should have fitted appropriate protection within the fan, the ocpds we install are not there to protect appliances, they are there to protect the cables which feed the appliances.

 

[brianmoooore]

Not sure I'd like to argue that in front of a Coroner's court.
Fortunately, in the case I referred to, no Coroners were involved, although the property in question received serious damage to its roof, and presumably, water damage throughout the rest of the house.
I normally only fit triple pole fan isolators alongside in line fans in lofts, and supply the whole lighting circuit to the bathroom through a switched FCU, fitted with a 3A fuse as per most manufacturers instructions.
Wall mounted fans, which I try to avoid because of their comparatively poor extraction rate and noise, just get the switched FCU.