Amendment 3 switch fuse

[Leesparkykent]

I'm pricing 28 new build flats and the QS for the job has specified amendment 3 switch fuses for each flat. TBH I'm not fussed either way as there is nothing in the price and I prefer them anyway as seem a lot stronger and the internals are better. These will be installed in a plant room for the distribution circuits to each flat. IMO I don't think they need to be of AM3 style as 421.1.201 says within a domestic household premises.....What's your opinion?

 

[Octopus]

If you are running SWA for the sub mains then AMD 3 switch fuses make perfect sense.

 

[Leesparkykent]

If you are running SWA for the sub mains then AMD 3 switch fuses make perfect sense.

I would use metal switch fuses like the 2nd pic any how. The 1st pic is an amendment 3 switch fuse which has a metal flap to cover switch and fuse carrier. I wouldn't consider a plastic switch fuse like a KMF as I think there rubbish but have a purpose if you have to install a switch fuse in a small space but that's about it IMO.

 

[7029 dave]

I would use the second S/F, because I am used to this product, been going for donks.Daft question just because it does not have cover over switch does that not make it am3 compliant. If it going to be in a locked switch room IMO it's fine.

 

[Leesparkykent]

I would use the second S/F, because I am used to this product, been going for donks.Daft question just because it does not have cover over switch does that not make it am3 compliant. If it going to be in a locked switch room IMO it's fine.

The IET wiring matters document and bema document suggest that to be amendment 3 compliant the internals should be completely enveloped with a non combustible material hence the reason the 1st switch fuse has a metal flap, metal hinges and a metal catch/screw to hold the lid up. I've always used ones like the 2nd pic since I started my apprenticeship. IMO shouldn't need ones like the 1st pic unless was actually installed within a domestic household premises. I don't think the communal area/switch room of a block of flats falls under such definition.

 

[HappyHippyDad]

If the spec says 'amd 3' switch fuses need to be fitted then I guess you'll have to fit the first one Lee, unless you specifically agree with whomever specified the job that the non-amd 3 ones are acceptable. Of course they are fine, but I'd be a bit worried after fitting 28 of them that they then get rejected for not being and 3!

Why do you ask? Would it not be more simple just to fit the first and avoid any problems? I'm guessing you prefer the second one in some way.

 

[Leesparkykent]

If the spec says 'and 3' switch fuses need to be fitted then I guess you'll have to fit the first one Lee, unless you specifically agree with whomever specified the job that the non-amd 3 ones are acceptable. Of course they are fine, but I'd be a bit worried after fitting 28 of them that they then get rejected for not being and 3!

Why do you ask? Would it not be more simple just to fit the first and avoid any problems? I'm guessing you prefer the second one in some way.

no I agree with you, I'm going to fit them and wouldn't even query it.. It was more for my own clarification for the future as I design and install lots each year. From April 2016 to April 2017 I would of done 83 flats and 22 houses.

 

[HappyHippyDad]

no I agree with you, I'm going to fit them and wouldn't even query it.. It was more for my own clarification for the future as I design and install lots each year. From April 2016 to April 2017 I would of done 83 flats and 22 houses.

Oh I see, sorry, misinterpreted the post.

 

[Richard Burns]

I do notice that all switch fuses that are not made for an AMD3 application do not mention compliance with BSEN61439-3, they only state BSEN60947-3.
This would indicate to me that a normal switch fuse assembly is not a type tested assembly for BSEN1439-3 and therefore by virtue of regulation 421.1.201, that says consumer units and similar switchgear should be compliant with BSEN61349-3, that a switch fuse is not a "similar switch gear" as it is not related to BSEN61439-3.
However I am not certain my belief would be upheld, as Wylex, who tend to do things way above what is required or sensible in relation to the wiring regulations, have decided to type test their AMD3 switch fuses to BSEN61439-3!

Considering 421.1.201 in general it states it is applicable to domestic (household) premises (which is not defined) but could almost certainly be not applied to a communal area in a block of flats.

Countering this is BSEN61439-3 that refers to distribution boards intended to be "operated by ordinary persons", which may happen if the owner was attending a problem for the flats. However the standard does not cover as one of their examples BSEN60947-3, but it does not exclude it either.

I would say, in general, for a block of flats that has a proper area designated for the incoming supplies that this would not come under 421.1.201.