Basic insulation exposed in electrical outdoor meter box.

If the door has fallen off, or the lock is broken, then it's not an enclosure any more.

Yes, ordinary consumers can and do open meter boxes.  The risk is really very low provided everything inside has basic insulation.

I entirely agree with the point that Mike is making, save that 412.2.2.1 refers to an "insulating enclosure".

Moreover, whilst it appears to be IP2X, I would not want to expose it to the elements, (though I have seen a metal CU outdoors).

An electrical enclosure requiring a tool to open might be the bolted metal cover over a live bus-bar with no additional insulation whatsoever, or not just the outer flap of a consumer unit but the whole front panel.

I'd argue an open  meter box ought to more like this sort of open enclosure

(even though it opens with a tool still)

as it is intended for 'instructed' or 'ordinary' persons to have access.

Rather than this level of an open enclosure , which of course is still 'the same' as far as the opens with a tool test is concerned.

but I'd argue should be left to those more 'skilled' or dare I suggest 'competent'  persons who can see the wiring and the bare metal bits and

don't experience a 'must touch' reflex...

The two sorts of electrical enclosing that are going on are not really equivalent.

If you'd be happy with that in a meter box, I dont know, but  I'm not, even if the exposed bus bar tabs were covered

Really we need a succinct phrase that distinguishes these two far from identical cases,

Calling both 'electrical enclosure' is not really capturing the difference in risk.
Mike.

I accept that a meter cabinet is capable of providing the supplementary insulation portion of double insulation, but then care would be needed with the earthing conductor.

If the MET were in the distribution board and connected to the service head by a length of G/Y, all well and good; but if the traditional MET consisting of a steel block with two rows of screws, especially with a TN-S supply, is in there, it needs to be insulated and marked (412.2.2.4).

Or it simply is not an enclosure.

This still leaves open the debate about the SWA not being terminated correctly and WHY a meter cabinet/cupboard does not mandate that ONLY rear or bottom entry with the penetration being correctly seeled. Entry points need to be discussed further as the Bend Radius for SWA is quite different to Flexy Tails or Split Concentric cable.

Below is my attempt at some possible wording.

All meter box penetrations MUST be from Below or REAR and MUST/SHALL be Gasket or INTUMESCENT SEALED.  SIDE or TOP penetrations are FORBIDDEN into the meter cabinet/cupboard.

IF SWA is used in the meter cabinet/cupboard then it MUST be Terminated correctly, this may take the form of an approved glanding into a WISKA box (other brands are available). There MUST NOT be SWA single insulation on show.  Non approved SWA glands are FORBIDDEN.  The same applies to Split Centric cables.  The Split Con MUST be terminated correctly or to manufacturers instructions.

In summation the meter cabinet SHALL have cables that ARE double insulated to provide an extra safety layer, protecting Property, People and Live Stock on the CUSTOMER SIDE with a functional and intact door. 

Maybe the next amendment/edition of BS7671 can clarify that an OUTDOOR meter box/cupboard is NOT the same as a Electrical Enclosure because 

The average Un-Skilled person would not normally enter an electrical enclosure, but they DO enter the OUTDOOR meter cupboard/cabinet for legitimate reasons like to read the meter or top up the meter on a prepay or to advise the DNO of the flashing light colour during a power-cut.

What happens when the door to the cabinet is missing or damaged

Same as if any other item of electrical apparatus is damaged... other than considering if it was suitable for the conditions in the first place, it's just life - hopefully people will be sensible enough not to use damaged equipment or keep their fingers out if it can't be de-energised, and it'll be picked up by the next inspection.

I do agree though that I don't consider a meter box to be an "electrical enclosure" in the same sense as say a joint box - on the basis that ordinary persons have good reason to access the inside of it. The problem we have is that the words in the regs seemingly don't justify that common sense (?) point of view.

   - Andy.

Chris Pearson said:

Given that the live conductors already have basic insulation, and accordingly, basic protection, the meter cabinet can hardly be providing it as well.

I'm not sure I follow, in terms of Regulation 410.3.2. Isn't the point that the combination of "enclosure + basic insulation" is providing the equivalent of double or reinforced insulation (it's basic protection + mechanical protection) per Regulation 412.2.2.1?

Definitions and interpretation again!

Enclosure. A part providing protection against certain external influences ... ticks that box ... and in any direction providing basic protection. Not sure about that.

Basic protection. Protection against electric shock under fault-free conditions. NOTE: For low voltage installations, systems and equipment, basic protection generally corresponds to protection against 'contact of persons or livestock with live parts'.

This thread is about exposed basic insulation.

Basic insulation. Insulation applied to live parts to provide basic protection ...

Given that the live conductors already have basic insulation, and accordingly, basic protection, the meter cabinet can hardly be providing it as well.

If there is, for example, a REC2 in there, the actual switch sits in its own enclosure, otherwise its terminals would be exposed. I suggest that the cabinet's purpose is to protect the DNO's tackle from the weather rather than to protect persons (and livestock) from it.

What happens when the door to the cabinet is missing or damaged, thus allowing access without a key or a tool?

The average Un-Skilled person would not normally enter an electrical enclosure, but they DO enter the OUTDOOR meter cupboard/cabinet for legitimate reasons like to read the meter or top up the meter on a prepay or to advise the DNO of the flashing light colour during a power-cut.

Additionally if the SWA in not Glanded correctly then moisture ingress can occur and corrode the armour of the SWA