Good question. We've discussed this before and I don't think came to any definite conclusion - so it would be good to have another try.

I quite agree the 'use of a key or tool' could mean almost anything - and a lot of possible interpretations do feel quite inappropriate.

I would throw in that the part 2 definition of an Enclosure is "A part providing protection of equipment against certain external influences and in any direction providing basic protection"  (my emphasis) - the last bit isn't clear to me but I guess you could read it as if the box isn't providing basic protection then it's not classed as an enclosure - so if the bits inside the box (cutout, meter, basic insulation of cables) are providing the basic protection then the outer meter box isn't - so it's not an enclosure, so can't be regarded as such for 412.2.2. etc.

The trouble with that approach is then we find that the likes a terminal strip in a plastic adaptable box would then fall outside of the definition too - which probably isn't what we want either.

   - Andy.

Les Board said:

so they can read the meter

What, no smart meter?!

I wouldn't get too concerned about it. The cabinet protects the contents, and even if a householder does have a key, they have no need of doing anything in there other than looking.

It is accessible to any member of the public with a key - which excludes toddlers, pets, and casual passers by. It also provides a lot more protection than if it was not there and the meter was screwed to the wall and left out in the rain and to be hit by passing trolleys or prams.

It does rather fall down the gaps in the rules as a halfway condition - it is not really the "open with a tool" that applies to a chamber with live bus bars, but neither is it open to all.

In practice the risk is low. Is it regs compliant, probably, more or less.

Mike.