I am sure that Mike will tell us, but it does seem sensible to label water bonding, gas bonding, etc.

AJJewsbury said:

I thought the N/PE cover on most cutouts was normally sealed

This is after the N/PE split, so it is just the PE.

I shall post pictures tomorrow.

Chris Pearson said:

This is after the N/PE split, so it is just the PE.

Usually, at that point, it's often the same block for N and PE ... at least at the service head itself.

So, perhaps labelling it as "PE" alone is not quite right?

However, at my sister's house, there is a DNO earthing terminal, that's brought off the Neutral, and has a DNO earth electrode connected ... because it's PNB.

Again, all belongs to the distributor, but ...

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.

I see what you mean. I had not quite remembered the service head properly. However, the PE terminals are accessible to an ordinary person.

Perhaps the terminal constitutes the MET? "The terminal ...provided for the connection of protective conductors ... to the means of earthing."

Chris Pearson said:

However, the PE terminals are accessible to an ordinary person.

In some designs of service heads. In others, even from the same manufacturer, you need to remove a screw that is accessible only when the service fuse carrier is removed from the head (in fact, there is one of those Series 7 with a fixed block and no access to the consumer on the demo board I pictured earlier in the thread).

Chris Pearson said:

Perhaps the terminal constitutes the MET?

Not in my opinion, it's not part of the electrical installation.

In my opinion, in BS 7671 speak, the earth block on the service head is the means of earthing, see Fig 2.1 in BS 76771 ... but if I remember correctly, in ESQCR it's the Distributor's Earthing Terminal.

I cannot argue with that interpretation, but is not exactly crystal clear.

gkenyon said:

Series 7 with a fixed block and no access to the consumer

Like this one!

Clearly, in this instance (TN-S/PILC), there has to be a separate MET.

gkenyon said:

only a court can decide on the interpretation of a standard in given circumstances

So the Judge might apply the "mischief rule", i.e. what is the problem which the statute is intended to remedy? If the purpose of 514.13.1 is to warn people not to disconnect earthing and bonding conductors where they are accessible at either end, it ought also to apply to my situation.

(I might add that there is nothing which prevents me from putting a notice there.)