"Electrical Fault" Definition

[JohnW2]

The "non-combustible material" requirements only apply to consumer units. A meter or isolator is not a consumer unit.

To be fair it does say "consumer units and similar switchgear assemblies", so there is some scope for debate about the likes of isolators - and there has been debate about that here, not the least in relation to the problems posed by metal pre-CU isolators in TT installations.

Kind Regards, John

 

[EFLImpudence]

To be fair it does say "consumer units and similar switchgear assemblies", so there is some scope for debate about the likes of isolators

There might have been (needless) debate but not according to the definition of CU in the Wiring Regulations.


Edit - should be "Definitions of CU and switchgear".

 

[ajohn]

The "non-combustible material" requirements only apply to consumer units. A meter or isolator is not a consumer unit.

Some electrician were interested so posted a photo of what they had done. In some areas as they are directly off the supply think in terms of a metal box with a rotary switch with lever. Also switched fuse units for sub mains and metal boxes with switches in them. It makes little sense to install a plastic part where other things can't be in the same area and are only protected by the supply fuse when it's ruled out for other similar items.

 

[EFLImpudence]

What?

 

[JohnW2]

There might have been (needless) debate but not according to the definition of CU in the Wiring Regulations. Edit - should be "Definitions of CU and switchgear".

I would think that the BS 7671 definition of "Switchgear" is sufficiently vague as to leave scope for debate as to whether an isolator qualified.

I would suspect that many people would regard a switch-fuse as being "switchgear" - does that mean that, in your opinion,the presence of a fuse makes a difference?

Kind Regards, John

 

[JohnW2]

....In some areas as they are directly off the supply think in terms of a metal box with a rotary switch with lever. Also switched fuse units for sub mains and metal boxes with switches in them. It makes little sense to install a plastic part where other things can't be in the same area and are only protected by the supply fuse when it's ruled out for other similar items.

I'm afraid that it continues to be difficult (at least for me) to understand what you are trying to say.

Kind Regards, John

 

[EFLImpudence]

I would suspect that many people would regard a switch-fuse as being "switchgear" - does that mean that, in your opinion,the presence of a fuse makes a difference?

That's what the definition says.

"An assembly of main and auxiliary switching equipment".

Not saying it makes sense but that is what it says.

 

[JohnW2]

That's what the definition says. "An assembly of main and auxiliary switching equipment".
Not saying it makes sense but that is what it says.

As so often, the wording is far from idea.

However, given the wording as-is, in what sense does a fuse qualify as "main switching equipment" or "auxillary switching equipment", such that adding it to a switch turns something which is not "switchgear" into something that is?

I suspect that they intended to (or should have) written " ...and/or..." - but. even then, there would still be some lack of true clarity

Kind Regards, John

 

[EFLImpudence]

"Auxiliary - providing supplementary or additional help and support."

An isolator does not have that.

I suspect that they intended to (or should have) written " ...and/or..." -

...but they didn't.

Can't have it both ways.

 

[JohnW2]

"Auxiliary - providing supplementary or additional help and support.". An isolator does not have that.

It doesn't - but does a switch-fuse?

We could go on for ever playing the game of scrutinising the apparent 'imperfections of BS7671 definitions (particularly when defined words are used in combination), but I doubt that would be very useful.

Would you really say that, say, a cabinet containing a number of high-current switches (and nothing else) was not "switchgear", because it contained nothing other than switches?

I imagine that a substantial proportion of the loose connections in CUs which could potentially result in overheating and fires involve connections to the main switch, rather than any other components, so I would think that a 'non-combustible' requirement in relation to isolators would be consistent with the LFB's views that apparently led to the regulation.

In passing, I'm mildly surprised that the LFB's eyes did not also fall on (increasingly 'ubiquitous') plastic-cased meters - which, again, are not immune from 'loose connections'.

Kind Regards, John

 

[EFLImpudence]

Switchgear: "An assembly of main and auxiliary switching equipment".

Would you say one can have a single item of auxiliary switching equipment on its own?

 

[JohnW2]

Switchgear: "An assembly of main and auxiliary switching equipment". Would you say one can have a single item of auxiliary switching equipment on its own?

As I said, the wording is probably not ideal, and that "...and/or..." would probably have been closer to what they really intended.

As I asked, do you believe that, just because of that "and", a cabinet containing a number of high-current switches (and nothing else) does not qualify as "switchgear" ... or are you perhaps saying that it would qualify as "switchgear" if it contained (just) two switches, but not if it contained only one?

Kind Regards, John

 

[EFLImpudence]

As I said, the wording is probably not ideal, and that "...and/or..." would probably have been closer to what they really intended.

How can we tell what they intended when it's not what they wrote?
Let's go with what they wrote and their definitions.
Perhaps the LFB have never blamed an isolator.

As I asked, do you believe that, just because of that "and", a cabinet containing a number of high-current switches (and nothing else) does not qualify as "switchgear" ...

By their definition, no.
Plus - that would not, presumably, be auxiliary to a consumer unit.

or are you perhaps saying that it would qualify as "switchgear" if it contained (just) two switches, but not if it contained only one?

Do you think one is a main switch and the other auxiliary to it?

 

[JohnW2]

As I asked, do you believe that, just because of that "and", a cabinet containing a number of high-current switches (and nothing else) does not qualify as "switchgear" ... or are you perhaps saying that it would qualify as "switchgear" if it contained (just) two switches, but not if it contained only one?

By their definition, no.

Given the multiple parts to my question (some of which contain the word "not"), I'd be grateful if you could clarify what you mean by "no". Thanks.

Kind Regards, John

 

[EFLImpudence]

Two switches would not alter the definition of switchgear.