MSF100 Switch fuses and amended regs

[ban-all-sheds]

I am very perplexed.

I cannot for the life of me understand why nobody, myself included, has ever, in all the times this issue has been discussed, considered what "combustible" means. If someone has, I've missed it. And everyone, myself included, has certainly missed a crucial part of the definition whenever they've said that nothing is non-combustible.

So....

421.1.201 Within domestic (household) premises, consumer units and similar switchgear assemblies shall comply with BS EN 61439-3 and shall:


(i) have their enclosure manufactured from a material which is not able to catch fire and burn easily , or


(ii) be enclosed in a cabinet or enclosure constructed of a material which is not able to catch fire and burn easily and complying with Regulation 132.12.​

Does a material which self-extinguishes burn easily?

 

[JohnW2]

Does a material which self-extinguishes burn easily?

That word 'easily' is as undefined in BS7671 as is "non-combustible" itself - so I don't think this really changes anything much (other than it may negate your argument that the regulation is "invalid").

Kind Regards, John

 

[JohnW2]

No, I have no 'insider knowledge' of the machinations of the JPEL. If you go to any of the Elex exhibitions you could try asking IET staff there.

I expected that. However, I thought that, from your experience, you would probably know roughly how long before publication of a Standard the DPC usually appears.

Kind Regards, John

 

[stillp]

I cannot for the life of me understand why nobody, myself included, has ever, in all the times this issue has been discussed, considered what "combustible" means.

Ooh goody. Now we can discuss what "easily" means! "Combustible" isn't directly defined in my COED, but it is listed as a derivative of combust, verb, to burn or be burnt by fire. It follows that the antomym non-combustible would mean not capable of burning or being burnt by fire. I would guess that's pretty much what most of us have considered to be the meaning.

 

[stillp]

I thought that, from your experience, you would probably know roughly how long before publication of a Standard the DPC usually appears.

Not for BSs. I work mostly with IEC and CENELEC, where the publication of a DPC depends on the stage, not any particular date.

 

[ban-all-sheds]

That word 'easily' is as undefined in BS7671 as is "non-combustible" itself

Is "easily" not defined in dictionaries?

If BS 7671 uses everyday English words without giving them a special definition, what definitions can be used except the everyday ones?

 

[stillp]

Is "easily" not defined in dictionaries?

It is, but without a description of how to verify if something burns easily.

 

[ban-all-sheds]

How reasonable would the average person think it to describe a self-extinguishing plastic as per the needle flame/glow wire tests in IEC 60695 as something which does not burn easily?

 

[stillp]

How reasonable would the average person think it to describe a self-extinguishing plastic as per the needle flame/glow wire tests in IEC 60695 as something which does not burn easily?

Well, the product committee for 61439-3, and at least some of the manufacturers, thought it sufficient, but the marketplace seemed to prefer to use metal enclosures.

 

[JohnW2]

How reasonable would the average person think it to describe a self-extinguishing plastic as per the needle flame/glow wire tests in IEC 60695 as something which does not burn easily?

I would find it difficult to answer that question for myself, let alone on behalf of "the average person". What is your view?

Kind Regards, John

 

[JohnW2]

Well, the product committee for 61439-3, and at least some of the manufacturers, thought it sufficient, but the marketplace seemed to prefer to use metal enclosures.

Yes, but that's surely because they wanted to be sure that they were compliant with BS7671 and, as the reg is currently worded, ferrous metal is the only material which one can be essentially certain is regarded as compliant?

Kind Regards, John

 

[stillp]

They were already sure John. Several (including my ex-employer) produced guidance stating that conformity to 61439-3 was sufficient, but they had to change their approach.

 

[stillp]

roughly how long before publication of a Standard the DPC usually appears.

I can tell you there's a proposal to revise the standard for cut-outs: https://standardsdevelopment.bsigroup.com/projects/4e2d657ccf03035b5d711f70db990a3c

 

[ban-all-sheds]

I would find it difficult to answer that question for myself, let alone on behalf of "the average person". What is your view?

My view is that if something is self-extinguishing it does not burn easily.

 

[stillp]

My view is that if something is self-extinguishing it does not burn easily.

Not sure I would agree. Some materials will burn easily, provided they're in contact with a flame or a hot surface, yet will self-extinguish if that flame or hot surface is removed.