Fusing Down Extract Fan To 3A

[Noob2013]

Hi all,

Most manufacturers state that their extract fans need to be fused down to 3A.

I don't know many sparks that actually do this, however I did on my last one.

I'm looking at doing this again but a different method.

Has anyone ever fitted an in - line fuse holder with a 3A fuse in the box with the fan isolator? Saves fitting a FCU.

The other method I'm toying with is a grid plate with fan isolator and 2 fuse holders (perm and switch).

Opinions please.

Thanks

 

[Andy78]

You could also use one of these
Excel 3 Pole Fused Fan Isolator Switch - White | QVS Electrical Wholesalers

Or even consider fitting a 3A MCB should the rest of the circuit agree to this.

Or you could, as you say a lot do, forget about this silly stipulation altogether and still get a good night's sleep.

 

[Darkwood]

There was a case where a fan caught fire due to poor design by the manufacturers and caused an house fire, the manufacturers got away with it because the Electrician hadn't fitted a 3amp fuse as stated in the bumf ... the Electrician was prosecuted but I don't know the outcome, so yes do fit one, I would make it a serviceble part for the customer so external in case the user needs to replace it, otherwise the manufacturers would fit it internally themselves.

 

[Leesparkykent]

Just get a fan that doesn't state it needs fusing down to 3amp.

 

[telectrix]

or open the bloody window. nesh lot we have in this country.

 

[RyanCheetham]

I use the grid method with 2 fuse holders in a dual outlet box so fuses and 3pole iso are side by side

 

[Noob2013]

So much up roar about all this due to one incident made public.

Surely the fault would cause the 6a MCB to trip if it was that severe.

 

[Noob2013]

My thought was the grid method

 

[davesparks]

2 fuses feeding one piece of equipment?

 

[Noob2013]

2 fuses feeding one piece of equipment?

One for the permanent and one for the switch

 

[Noob2013]

Am I right in saying that if there is a window then it doesn't need an isolator?

 

[davesparks]

One for the permanent and one for the switch

I got that bit, what I don't get is how that could possibly be acceptable.
You then have a cable protected by two seperate, non linked ocpds, and still have the equipment potentially able to draw 6A.
If you are fusing down for the fan then it needs to be one fuse protecting the fan, not two.

 

[Dave OCD]

That does make it a bit strange, far better IMO to route the initial supply to the bath/shower room lighting through a 3 amp fused unswitched FCU - but Lee has the best idea, avoid such fans in the first place.

 

[Noob2013]

Which fans do not state that it needs to be fused down? Most I have come across do

 

[davesparks]

Am I right in saying that if there is a window then it doesn't need an isolator?

Please explain your thought process here?
I'd love to know how you think a window is going to have any effect at all on the requirements for isolation and switching.

 

[Dave OCD]

Am I right in saying that if there is a window then it doesn't need an isolator?

That's nonsense, whether you can see the fan properly or not without artificial light when cleaning or maintaining it it should be isolated.

 

[Noob2013]

That's nonsense, whether you can see the fan properly or not without artificial light when cleaning or maintaining it it should be isolated.

Mcb could be isolated?

 

[Dave OCD]

Yes but surely the idea is that you can have the fan isolated in ALL poles for cleaning by 'non electrical' people but still have the local lighting operational if required.

 

[Octopus]

Which fans do not state that it needs to be fused down? Most I have come across do

Greenwood, if supplied from a 6A MCB or RCBO

 

[davesparks]

Mcb could be isolated?

Which defeats the object of the isolator in the first place.

The whole point of fitting an isolator for a specific piece of equipment is to allow that piece of equipment to be isolated. This is a basic principal of electrical installations that runs through from the little domestic fan right up to the biggest multi-million pound machine.

 

[Leesparkykent]

Which fans do not state that it needs to be fused down? Most I have come across do

Vent-axia

 

[Octopus]

Mcb could be isolated?

hum... a fixed piece of equipment with the only isolation being the MCB - thats going to be OK until the RCD starts tripping and you want to quickly isolate the appliance and can't!

 

[Noob2013]

I always fit an isolator without fail. Safer and more convenient. I was just asking about the whole window situation as I've heard other sparks mention it.

 

[Leesparkykent]

I had a customer once that was adamant that she didn't want the fan isolator......it was an inline fan situated in the loft so I ended up putting it on a 4pin klik rose.

 

[uksparks]

I phoned manrose about this, they confirmed to me that you only need a fuse in the permanent live and not switched live as its the permanent live that will have the draw on it from the fan and the switched live is literally a trigger, so they said fit a 3 pole isolator with a single fuse in the permanent live only.

what do you make of this? I tend to agree with it, plus if you are doing maintenance on the fan you should use the 3 pole isolator so it kills all power.

 

[davesparks]

I had a customer once that was adamant that she didn't want the fan isolator......it was an inline fan situated in the loft so I ended up putting it on a 4pin klik rose.

For inline fans I always fit one of them or a blue click flow connector next to the fan. I was taught that a means of isolation should always be located next the the equipment it isolates wherever possible.

Also for 3 pole isolator switches I fit them at socket height rather than above door height as I think it looks ridiculous and sticks out like a sore thumb.

 

[davesparks]

I phoned manrose about this, they confirmed to me that you only need a fuse in the permanent live and not switched live as its the permanent live that will have the draw on it from the fan and the switched live is literally a trigger, so they said fit a 3 pole isolator with a single fuse in the permanent live only.

what do you make of this? I tend to agree with it, plus if you are doing maintenance on the fan you should use the 3 pole isolator so it kills all power.

It sounds fishy to me, but without actually having a look at the pcb and working out the circuit it's hard to say. Somehow I doing that there is good isolation between them on that little pcb and I can see a bit of condensation causing a fault on the sw/l

 

[Lazlo]

Sometimes when we have dimmed bathroom lights we use Click minigrid with the dimmer module on one side and a retractive switch the other side to trigger the fan, you could always incorporate the minigrid 13A fuseholder into this grid to fuse the permanent live feed for the fan (and the switched if you were inclined to). Personally I don't think there is an easier or more smart looking system for domestic sparks than the Minigrid, I use it all the time. Your 3pole isolator should be located outside zones, usually we pout them high level above door etc or pullcord 3pole iso in airing cupboard.......

 

[Deleted member 9648]

I had a customer once that was adamant that she didn't want the fan isolator......it was an inline fan situated in the loft so I ended up putting it on a 4pin klik rose.

Well hang your head in shame fella......such things are classed as LSC's and are not to be used for any other purpose,dont have the BYB to hand but 559.6.1.4 applies I believe.

 

[Midwest]

Just searched this on this forum/google, gets posted every few months, with the same responses. There's the 'don't bother', or use a 'TP isolator with 3a fuse in the permanent live' or change the mcb to 3a. There was even one clever forum member who came up with a wiring design (can't find it here now), with fused fcu protecting both sw + perm' Live. I printed off a copy and kept in my van........never used it though. Some of our members say that 3a fuse protecting a motor that draws much lees than 1a is pretty pointless, in terms of overload. Wonder when it will next get posted!

 

[mhar]

This is a reply I gave on a previous thread :-
In reply to the op it is possible to achieve fan isolation of all lives, fusing of both lines and have the bathroom light unaffected by fan isolation using just a dp sfcu and a dp light switch. The wiring is a bit 'busy'.
Supply into dp switch, two x two core cables to sfcu and one x three core from sfcu to fan. Connect as follows :- Supply l to dp light sw S1, n to wago in light sw back box. Using one of the two cores cables, light sw S1 to sfcu l supply, sfcu l load back to light sw S2. Second two core, light sw L2 to wago in sfcu back box, n from light sw wago to sfcu supply n. 3 core is connected to sfcu l load, sfcu n load and switched line to sfcu wago. The light is connected to dp light sw L1 and n to light sw n wago.
Description looks confusing but draw it out.

 

[mhar]

Vent-axia

Have a read of this. http://www.vent-axia.com/files/pdf-downloads/438680.pdf 1A fuse required!!!

 

[Leesparkykent]

Have a read of this. http://www.vent-axia.com/files/pdf-downloads/438680.pdf 1A fuse required!!!

Link doesn't work...If I remember correct the vent-axia silhouette fan has a diagram showing it fed of a lighting circuit with no 3A fuse.

edit: found diagram

 

[Deleted member 9648]

Well hang your head in shame fella......such things are classed as LSC's and are not to be used for any other purpose,dont have the BYB to hand but 559.6.1.4 applies I believe.

Edit....559.5.1.203 in the BYB !

 

[Richard Burns]

This is a reply I gave on a previous thread :-
In reply to the op it is possible to achieve fan isolation of all lives, fusing of both lines and have the bathroom light unaffected by fan isolation using just a dp sfcu and a dp light switch. The wiring is a bit 'busy'.
Supply into dp switch, two x two core cables to sfcu and one x three core from sfcu to fan. Connect as follows :- Supply l to dp light sw S1, n to wago in light sw back box. Using one of the two cores cables, light sw S1 to sfcu l supply, sfcu l load back to light sw S2. Second two core, light sw L2 to wago in sfcu back box, n from light sw wago to sfcu supply n. 3 core is connected to sfcu l load, sfcu n load and switched line to sfcu wago. The light is connected to dp light sw L1 and n to light sw n wago.
Description looks confusing but draw it out.

Like this?

 

[uksparks]

Yes that makes sense, the only thing is if you wanted to do it from a pull cord you would need to use a double pole one not just your ordinary type.

im just thinking about this layout as have a couple of extensions I'm working on so might just reconfigure it slightly to work this way.

i know it's obvious in a way but thanks for sharing it.

 

[uksparks]

*** deleted

 

[dnjr]

Don't think the environvent silent 100 needs a fuse Worth a look it's a reasonable fan

 

[marc8]

we fit 3amp circuit breakers for bathrooms normally get 2 from one, this helps split lighting circuit up also, if we have multiple bathrooms en-suites utilities ect then we grid switch from 6-10amp circuit breakers.