haeyun kim said:

(iii) the main earthing terminal; where separate from main switchgear

The wording isn't exactly unambiguous. For example, in the diagram, is the service head separate from the main switchgear? I guess plenty of sparks would contend that it is immediately beside and therefore not separate, as distinct from the case where it is separate when the consumer unit is in the house and the service head is in the outside meter cubicle.

For the same reason, I would contend that the MET in the diagram is not separate from the main switchgear and therefore does not need a label. 

lyledunn said:

For the same reason, I would contend that the MET in the diagram is not separate from the main switchgear and therefore does not need a label.

That's an interesting perspective. I don't agree, because it's the noun form of 'separate' that is used, rather than the verbal form - it does not say 'separated from' but 'separate from'. Hence, I've always been of the opinion that 'separate from' being 'not part of' [the assembly that is] main switch gear, and would use 'separated from' if I intended Lyle's interpretation.

But it is only an opinion. Whilst anyone can provide their opinion, only a court can decide on the interpretation of a standard in given circumstances.

I had a look back, and the 15th and original (1991) 16th Edition did not require the MET to be labelled, only connections of earthing conductors to earth electrodes, and bonding conductors to extraneous-conductive-parts.

The current requirement (with current wording) I believe appeared in Amendment 1:1994 to BS 7671:1992, so has been in place for 30 years.

That's a very contrived interpretation of the word "separate".  The MET is not attached to the service head, and it's not the earth bar in the consumer unit.  It's definitely separate.

That's a very contrived interpretation of the word "separate".  The MET is not attached to the service head, and it's not the earth bar in the consumer unit.  It's definitely separate.

I was just pointing out how the interpretation of a word or phrase that is exact for some can often have a very different connotation for others. If we bolted the MET to the outside of the switchgear, it would no longer be separate from it. Strict reading of the indent would lead one to conclude that a safety notice would not be required. 

So the use of the word "separate" is not ideal if the regulation is trying to convey that a notice is not required if the MET is established within the main switchgear.

However, I am happy to lean towards Chris Pearson's view in terms of the mischief rule.

Interestingly, in the Irish Regs (IS1010-1) 2020 there is no requirement for a safety notice at the MET although, like BS7671 2018 A2 2022, 134.1.7 says "where necessary for safety purposes, suitable warning signs and/or notices shall be provided"

lyledunn said:

If we bolted the MET to the outside of the switchgear, it would no longer be separate from it.

I find it difficult to argue otherwise.

So is this one separate or not? (Strictly speaking, it is a building earth terminal rather than the MET.)

lyledunn said:

If we bolted the MET to the outside of the switchgear, it would no longer be separate from it.

Agreed, but you would be modifying the switchgear assembly, which is outside the scope of BS 7671. BS EN IEC 61439 series addresses marking requirements for the assembly.

lyledunn said:

So the use of the word "separate" is not ideal if the regulation is trying to convey that a notice is not required if the MET is established within the main switchgear.

I disagree based on the above.

lyledunn said:

However, I am happy to lean towards Chris Pearson's view in terms of the mischief rule.

I have no problem with that, BS 7671 is a "minimum" ...

lyledunn said:

Interestingly, in the Irish Regs (IS1010-1) 2020 there is no requirement for a safety notice at the MET although, like BS7671 2018 A2 2022, 134.1.7 says "where necessary for safety purposes, suitable warning signs and/or notices shall be provided"

Yes, BS 7671 (and preceding Wiring Regs) never used to have a requirement until 1994.

Chris Pearson said:

So is this one separate or not?

Clearly, yes, it's separate and not part of the assembly.