This is a question about (iii) of 514.13.1 of BS 7671:2022

This is a question about (iii) of 514.13.1 of BS 7671:2022.

 

BS 7671:2022

514.13.1 A durable warning notice with the words 'Safety Electrical Connection - Do Not Remove' shall be securely fixed in a visible position at or near:

(i) the point of connection of every earthing conductor to an earth electrode, and

(ii) the point of connection of every bonding conductor to an extraneous-conductive-part, and

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

 

Q) I am wondering where does (iii) refer to, and why it is necessary to install the warning notices there?

Parents
  • we seem to have lost a reply from Graham, but I'll have a go.  the MET is any sort of marshalling block where the green and yellow wires come together that is not inside another box. although the regs don't make it very clear there is often more than one - perhaps in the basement of a block of flats, and then again inside each flat. this sort of thing. The warning is because taking the site off-earth without isolating the supply first may well allow all the earthed metalwork to drift to a  painful voltage.

    Mike.

  • we seem to have lost a reply from Graham

    Yes, not sure why?

    EDITED ... but it has reappeared, perhaps popped onto the moderation queue?

  • And now the original post has re-appeared, I can link the two responses, which just happen to be complementary, by pointing out that the picture in the post from   clearly shows a more durable plastic notice, secured with screws ...

  • I love the wee flags!

    Most SP CUs nowadays seem to have a couple of terminals in the earth bar for bonding, but I am not sure that it was always so.

    The other thing is that my (ex-) TN-S supply has 4 weedy looking strands for insertion into the MET. They are not long, but do have a diameter of about 2¼ mm. It follows that a junction block (even with no bonding) was required.

    With modern TN-C-S service heads, there is a terminal for the earthing conductor.

    Should that have a warning notice?

  • With modern TN-C-S service heads, there is a terminal for the earthing conductor.

    Should that have a warning notice?

    The service head is not part of the consumer's electrical installation, and isl also outside the scope of BS 7671 ... so perhaps a question for the relevant DNO ?

  • Equally well, the earthing conductor is part of the consumer's installation, so where do you draw the line?

    The earth terminal is not sealed, in fact there is nothing more than a sort of dust cover over the terminals.

    I had never thought about this before, but the OP prompted the question.

  • I thought the N/PE cover on most cutouts was normally sealed - and even if it isn't it is rather more obviously part of electrical equipment that even ordinary persons shouldn't be tempted to mess with (similar to the earth bar in a CU not needing a label). Some larger (industrial) METs do look rather more mechanical than electrical to the untrained eye.

    Don't over estimate non-electrical types. I've seen an example of a plumber doing exactly what the label said, when replacing a gas pipe - they left 6" of the original pipe hanging in mid-air just so they didn't have to remove the original bonding clamp. Maybe the wording could have been better... (e.g. ensure it remains connected, rather than do not remove perhaps).

       - Andy.

  • ve seen an example of a plumber doing exactly what the label said, when replacing a gas pipe - they left 6" of the original pipe hanging in mid-air just so they didn't have to remove the original bonding clamp.

Reply Children
No Data