Extractor fan

[m4tty]

Hi,

Do all extractor fans have to be fused down at 3a? I know if it says in manufacturers instructions it must be followed, but have you ever come across a fan which is ok on a 6a breaker without having to put an fcu above the bathroom door fused at 3a.

Cheers

 

[Apache]

I think this is one of those manufacturers instructions that are often ignored - from past posts on here.

 

[kme]

I would say so......99% of the time, it will be fed from a local lighting cct, via a fan iso. I have put a fused spur in line, but the lighting cct was on a 16A breaker!

KME

 

[Lurch]

Can't say I've ever seen a fan fused down to 3A, if there has been a spur above the door then it's usually got a 5 or 13A fuse in it anyway, the fused spurs are usually only there as an isolator rather than for fusing down purposes IME.

 

[Revved Up Sparky]

If the lighting circuit is rated at 6A and I am installing a 12V timed fan then I would just use a triple pole isolator. I have on rare occasions seen FCUs used as isolators for these but the neutrals were linked through (which is incorrect) with only permanent live and switched live going through the FCU.

At other times, for example when I am installing humidistat controlled 12V fans, only permanent L, N & E are needed so I use an FCU and stick a 3A fuse in it. It only takes seconds so I do it anyway despite the circuit being 6A rated -... it also provides extra protection in the unlikely but possible event of some dodgy spark putting a 16A MCB into the CU then at least the fan still has 3A protection.

 

[Theorysparky]

I tend to put the lights in the bathroom through a 3amp fcu then use a 3 pole isolator for the fan

job done

 

[batty]

If the circut is on a b6 mcb would the mcb or the 3 amp fuse go first if there was a fault on the fan. Personally I use a triple pole fan isolator and really on b6 breaker for protection. Maybe not to manufacturers recommendation but I have found people do not like loads of switches outside there bathroom and the way I do it they can easily isolate fan and keep lighting worhking if there is a fault on fan and if you have a pee wee in the middle of the night fan doesn't run for 15 minutes when you have finished.

 

[SPECIAL LOCATION]

I tend to put the lights in the bathroom through a 3amp fcu then use a 3 pole isolator for the fan job done

Ditto.

I cant remember NOT putting a 3a fuse on a fan circuit..

(+ a 3pole isolator)

TBH seen too many of those little timer circuits get a bit burnt out and fail, I wouldn't feel safe leaving a fan without additional fusing.

:coffee

 

[m4tty]

If the lighting circuit is rated at 6A and I am installing a 12V timed fan then I would just use a triple pole isolator. I have on rare occasions seen FCUs used as isolators for these but the neutrals were linked through (which is incorrect) with only permanent live and switched live going through the FCU.At other times, for example when I am installing humidistat controlled 12V fans, only permanent L, N & E are needed so I use an FCU and stick a 3A fuse in it. It only takes seconds so I do it anyway despite the circuit being 6A rated -... it also provides extra protection in the unlikely but possible event of some dodgy spark putting a 16A MCB into the CU then at least the fan still has 3A protection.

Hi,

The builder said that the fan was a humidistat. I have never installed one of these before so want your advice please on the differences between these and normal extractor fans.

Do they not require a switched live at all, just a permanent live so they can work when they want to?

Cheers

 

[Lurch]

The builder said that the fan was a humidistat. I have never installed one of these before so want your advice please on the differences between these and normal extractor fans. Do they not require a switched live at all, just a permanent live so they can work when they want to?

It will depend on the exact fan. Most will require just a permanent feed, some have additional triggers for run on timers and overrides. More than likely the former though.

 

[m4tty]

thanks lurch I'm doing first fix tomorrow so as I'm probably not going to see the fan until second fix do you recon I should run 3 core just in case?

Thanks

 

[initforthemoney]

..... but the neutrals were linked through (which is incorrect)

Why?

 

[Revved Up Sparky]

Because in the event of a reversal of polarity or a bad neutral connection upstream the fan connections (ie the neutrals) would become live with FCU switched off. In order to provide safe isolation for mechanical maintenance all live conductors (including neutrals) need to be switched off. Sorry I have no reg number in front of me but if I am wrong I know I will be corrected

---------- AUTO MERGE Post added at 22:15 ---------- Previous post was at 22:11 ----------

thanks lurch I'm doing first fix tomorrow so as I'm probably not going to see the fan until second fix do you recon I should run 3 core just in case?Thanks

Hi matty. If I am ever unsure about the type of fan to be installed I always run a three core from the bathroom light point to the isolator/ FCU. This also allows the fan to be easily changed for a different type at a later date.

 

[batty]

Because in the event of a reversal of polarity or a bad neutral connection upstream the fan connections would become live with FCU switched off. In order to provide safe isolation for mechanical maintenance all live conductors (including neutrals) need to be switched off. Sorry I have no reg number but if I am wrong I know I will be corrected ---------- AUTO MERGE Post added at 22:15 ---------- Previous post was at 22:11 ----------

Hi matty. If I am ever unsure about the type of fan to be installed I always run a three core from the bathroom light point to the isolator/ FCU. This also allows the fan to be easily changed for a different type at a later date.

Please say three core and earth we don't want some plumber or diyer doing it with three core flex.

 

[Revved Up Sparky]

Please say three core and earth we don't want some plumber or diyer doing it with three core flex.

Three core & earth is what I meant. Thanks Batty.

 

[m4tty]

Sorry batty I meant 3c+e. Thanks for replies as always everyone. Cheers

 

[batty]

Just saying because I had to put one right the other day wired in three core flex and the cpc was switched live not very good really.

 

[tonksie]

as long as you sleeved it up

 

[Apache]

as long as you sleeved it up

Someone stated a reg where green and yellow cannot be sleeved and used as any other conductor!

 

[SPECIAL LOCATION]

as long as you sleeved it up

:_|

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