electricalforum.nz

"(e) in the case of a low voltage installation or part installation, do all of the
following:
(i) ensure that the polarity and phase rotation of the supply are cor-
rect:
(ii) ensure that the protection of the supply is correctly rated:
(iii) ensure that the installation or part installation to be connected is
compatible with the supply system:
(iv) if the supply is from a MEN system, verify that there is a main
earthing system."

In terms of a part installation, when it uses the term "supply" is it referring to the supply to the whole installation or simply to the part installation?

For example, I add to an existing final subcircuit, to confirm (e)(i) am I to check the polarity and phase rotation of the mains? Or am I simply checking this at the point I've added to where it's connecting too?

In general we're only responsible for what we do, and not for what was already there (except that we mustn't make existing stuff any less safe than it was).
Accordingly I believe the correct interpretation is that these pre-connection checks apply in terms of the supply to the "part installation" about to be connected. So for most of these checks, we don't need to go any further upstream than the point we're connecting at. However for the final item, "main earthing system" is a defined term, so if the new subcircuit (or whatever) is to be fed from an MEN system (as is normal); then we have to check that an MES exists for the installation we're adding to.

May I ask what your usual routine of verifying a MES is?

I usually just visually check inside the switchboard and then test MEC from electrode

What is your procedure if unable to visually locate an electrode? Install a new one or an alternative test method?

I suspect this requirement is mostly ignored.
But yes, i believe that a visual check plus continuity test confirms that a MES exists.
Nothing says it has to be off any particular standard or efficacy.

Would have to think about alternative tests that might be deemed adequate if electrode not readily found.

Not aware of any declarations by EWRB or ES on this point.