fuse for extractor fan

[sparkwright]

Bernard posted a diagram in another thread.

As can be seen in the diagram the fuse *does* connect directly to one of the poles on the isolator.

I suggest implementing this by using the isolator/fuse plate as the junction box. The light, switch and fan can then be connected to the isolator/fuse plate using normal T&E and 3+E cables.

Of course, on this diagram, the fuse protects the bathroom light as well.

There was a diagram on another thread where the 3amp fuse ONLY protects the fan (both perm live and sw live).

 

[sparkwright]

May we should just use 3amp circuit breakers or RCBOs at the mains.

 

[JohnW2]

Of course, on this diagram, the fuse protects the bathroom light as well.

True - but that's surely not a problem, is it? ... and simpler to implement than ...

There was a diagram on another thread where the 3amp fuse ONLY protects the fan (both perm live and sw live).

Indeed, there are ways - but, as has been discussed, there will (I think inevitably) then be a need for a DP light switch - which, as has been said, might be an inconvenience (and would usually require additional wiring).

Kind Regards, John

 

[JohnW2]

May we should just use 3amp circuit breakers or RCBOs at the mains.

In these days of LEDs, that would usually be feasible and would perhaps be appropriate IF there were a good reason for the fan needing protection by a 3A fuse, when there might be some point. However, as for that "IF", I'm not sure that I can see what that 'good reason' would/could be, particularly given that (as has been said) a B6 MCB would usually/often operate before a 3A BS1363 fuse!

In any event, even if that were done, I'm not convinced that it would necessarily stop the silly people who write the MIs still requiring an additional 3A fuse (in addition to the 3A MCB)!

Kind Regards, John

 

[sparkwright]

True - but that's surely not a problem, is it? ... and simpler to implement than ...


Kind Regards, John

I think typically this would usually require some rewiring too.

It's usually a good idea to run the supply cables, the switch cable, the light cable and the fan cable all back to the fan switch, and use the fan switch as a junction box, that way one of those fan switch fuse thingys can be wired easily and correctly.

 

[sparkwright]

I see no good reason for the 3amp fuse anyway.

 

[EFLImpudence]

I see no good reason for the 3amp fuse anyway.

There is none.


I am not sure what this thread is about now.

The equipment available allows whichever method anyone wants use.

 

[JohnW2]

I think typically this would usually require some rewiring too.

That presumably depends upon the actual situation and the degree of slack in cables. For example, given a stud-wall and just a little slack, one could probably insert an FCU in the feed to the light switch without the need for any additional cable/'wiring'. However, as said, I personally would certainly not bother.

It's usually a good idea to run the supply cables, the switch cable, the light cable and the fan cable all back to the fan switch, and use the fan switch as a junction box, that way one of those fan switch fuse thingys can be wired easily and correctly.

I'm not at all sure about your "usually" ("a good idea"), given that it's not something that I can personally recall every having seen done. Don't forget that, other in new builds or total re-wires, the fan and/or 'fan isolator' will often/'usually' have been added long after the light and light switch were installed.

As you say, that approach would facilitate proper use of one of the isolator+fuse thingies - but if the light and light switch were already present, it would require an appreciable amount of 're-wiring'.

Kind Regards, John

 

[JohnW2]

There is none.

I'm glad you agree.

I am not sure what this thread is about now. ... The equipment available allows whichever method anyone wants use.

I'm not sure what "equipment available" you had in mind, but if you are thinking of (or including) the isolator+fuse product then, as has been said, to install that properly/satisfactorily in an existing installation (existing light and light switch, maybe even fan) would usually involve an appreciable amount of 're-wiring'.

Given the uselessness of the fuse, the effort involved in implementing any of the 'methods' does not (at least to me) seem to be justified!

Kind Regards, John

 

[EFLImpudence]

I'm glad you agree.
I'm not sure what "equipment available" you had in mind, but if you are thinking of (or including) the isolator+fuse product then, as has been said, to install that properly/satisfactorily in an existing installation (existing light and light switch, maybe even fan) would usually involve an appreciable amount of 're-wiring'.

Yes, but after (me) telling the OP that he needs neither fuse nor isolator, the thread seems to have been -

well, you could do this , or this, or this, or that; all of which has been unnecessary apart from the equally unnecessary complying with some silly instructions..

 

[JohnW2]

Yes, but after (me) telling the OP that he needs neither fuse nor isolator, the thread seems to have been - well, you could do this , or this, or this, or that; all of which has been unnecessary apart from the equally unnecessary complying with some silly instructions..

All agreed.

We do not know what the OP did after you told him that (in post #4) and/or as a result of any of the discussion, since he does not appear to have showed himself since post #3 (of 55 posts) - i.e. the one before yours.

Having said that, and apart from the interests of the OP, I think the general discussion about the off-the-shelf "3 pole isolator + fuse" product has probably been valuable (and might be for others who find it in the future), not the least because I admit that I, for one, had not initially considered how it is very likely to be 'mis-used' by non-electricians - or maybe even some electricians.

Kind Regards, John

 

[RandomGrinch]

Yes, but after (me) telling the OP that he needs neither fuse nor isolator, the thread seems to have been -

well, you could do this , or this, or this, or that; all of which has been unnecessary apart from the equally unnecessary complying with some silly instructions..

It may be unnecessary, but it has certainly been worth it to me, for the education value!

Where else would a DIY'er have this sort of information laid out to them, questioning the validity (and even safety) of manufacturers instructions etc.

With nearly 450 views in a day, how many people will now be able to make informed decisions?

 

[EFLImpudence]

Fairy Nuff.