MSF100 Switch fuses and amended regs

[m109254]

I need to install a second switch fuse for a separate supply to an extension. Would prefer to use this model as they are small enough to fit onto existing board in a small cupboard where the supply enters the house (and leave room for the extra RCD that's now required) but concerned that they are plastic and Amendment 3 of 17th Edition regs says 'switchgear including consumer units' need to be of non combustible material. Can I use it or should I go for one of the bigger metal clad ones, replace the board and make the cupboard bigger - which is a whole lot more work?

 

[JohnW2]

I need to install a second switch fuse for a separate supply to an extension. Would prefer to use this model as they are small enough to fit onto existing board in a small cupboard where the supply enters the house (and leave room for the extra RCD that's now required) but concerned that they are plastic and Amendment 3 of 17th Edition regs says 'switchgear including consumer units' need to be of non combustible material. Can I use it or should I go for one of the bigger metal clad ones, replace the board and make the cupboard bigger - which is a whole lot more work?

Good question, but I don't think it's going to stop me using them anytime soon!

It probably does come within the scope of that new reg. However, no-one knows what "non-combustible" actually means (since nothing is literally non-combustible). They look to me as if they are made out of the same sort of (I think urea-formaldehyde) resin uses for standard 'white' accessories - and it is pretty difficult to persuade that stuff to burn in any real sense, so maybe that is 'adequately non-combustible'? Regs aside, it would certainly be 'non-combustible' enough for me!

Kind Regards, John
Edit: typo corrected

 

[m109254]

Thanks - very helpful.

 

[JohnW2]

Thanks - very helpful.

You're welcome, but I'm not so sure how helpful it was! Unless/until the regulation is improved (or removed!) no-one really has much of a clue as to what (if anything) other than 'ferrous metal' would satisfy it (and a few people even doubt ferrous metal since, whatever the note in the regs says, it is not 'non-combustible'!) It's a bit like replacing explicit speed limits with a law which outlawed "travelling at an excessive speed'!

Kind Regards, John

 

[stillp]

It doesn't have to be made of the "non-combustible" material though, if it is contained in a "non-combustible" enclosure.

 

[JohnW2]

It doesn't have to be made of the "non-combustible" material though, if it is contained in a "non-combustible" enclosure.

That's also true - but if we don't know what would be compliant as the 'non-combustible' casing of the product, nor do we know what would be compliant as a 'non-combustible' enclosure!

Kind Regards, John

 

[Risteard]

Amendment 3 of 17th Edition regs says 'switchgear including consumer units' need to be of non combustible material.

No it doesn't - it refers to "consumer units and similar switchgear assemblies". That is very different to "switchgear including consumer units".

 

[ban-all-sheds]

It's a bit like replacing explicit speed limits with a law which outlawed "travelling at an excessive speed'!

Which they did in Montana, I believe. It became a nice little earner - for some reason it was only ever out-of-state drivers in expensive cars who drove at excessive speeds.

 

[stillp]

That's also true - but if we don't know what would be compliant as the 'non-combustible' casing of the product, nor do we know what would be compliant as a 'non-combustible' enclosure!

Kind Regards, John

Perhaps not, but we do know that ferrous metal is considered to be a suitable example.

 

[JohnW2]

Perhaps not, but we do know that ferrous metal is considered to be a suitable example.

Indeed, unless one is BAS, who believes that the note in the regs that "ferrous metal ... is deemed to be non-combustible" has to be ignored, since it is a scientific impossibility!

Kind Regards, John

 

[ban-all-sheds]

Well - if you're going to allow people to deem materials to have properties which they do not in technical/engineering requirement documents, you wonder what the point is of having experts create the documents in the first place.

Maybe they've adopted the Govian approach of saying "Tell you what - let's not take any notice of people who do actually know what they are talking about."

 

[ban-all-sheds]

Indeed, unless one is BAS, who believes that the note in the regs that "ferrous metal ... is deemed to be non-combustible" has to be ignored, since it is a scientific impossibility!

There is a serious and valid point here.

Clearly ferrous metal is not non-combustible. It can be made to burn. Therefore, the concept of "deeming" it to be so can only be one of deeming it to be sufficiently non-combustible. In which case there are other materials which manufacturers, national and international standards organisations, and the legislators in advanced, civilised countries all consider to be sufficiently non-combustible to be used for electrical accessories.

 

[JohnW2]

There is a serious and valid point here. Clearly ferrous metal is not non-combustible. It can be made to burn. Therefore, the concept of "deeming" it to be so can only be one of deeming it to be sufficiently non-combustible.

Indeed - and I think that that is the sense it which rules, regulations and legislation commonly use the concept of "deeming". Let's face it, if ferrous metal really were non-combustible (which I don't think anything can be), then there would be no need to do any "deeming"

In which case there are other materials which manufacturers, national and international standards organisations, and the legislators in advanced, civilised countries all consider to be sufficiently non-combustible to be used for electrical accessories.

That's what many of us have been saying all along. However, given the absence of any other guidance in BS7671, no manufacturer could ever be sure than any other material was "sufficiently non-combustible".

I would add that "sufficiently non-combustible" is really a contradiction in terms. We probably should talk of "sufficiently low combustibility" or something like that.

Kind Regards, John

 

[ban-all-sheds]

Until we leave the EU and begin our journey to becoming a thirld-world country, I fail to see how a CU which can legally be sold in 27 other countries cannot be legally sold and installed here.

 

[stillp]

I fail to see how a CU which can legally be sold in 27 other countries cannot be legally sold and installed here.

Because installation standards are the prerogative of individual nations? Technically it would be legal, but how would you demonstrate compliance with Part P for a CU that did not appear to conform to BS7671?