I don't quite follow the 526.8 argument - aren't all the cores enclosed by the EV charger enclosure? 134.1.1 is, as ever, debatable and probably needs a reference to some recognised guidance to make it stick.

I think the stuffing gland approach was suggested by some official guidance some time back for isolating TN c.p.c.s. Personally I don't particularly like the approach as it doesn't make it simple to test the continuity/Zs at the load end of the armour - which you really should do if the armour is being relied upon for ADS for the cable itself (e.g. if the cable is buried or run through an environment where damage is a risk - and if it's not why bother with SWA?). The cable itself should be supported conventionally (e.g. by cleats/P-clips) as required and not rely on the termination of the armour for support. The stuffing gland approach does have the advantage of enuring there are no exposed-conductive-parts of the supply TN system (e.g. the brass gland) within reach of the EV's earthing system.

My preference would be for a brass gland into a plastic enclosure (perhaps the charge point itself, if the enclosure is insulating), covered with a PVC boot to prevent the gland being touched, with the secured in some way if needs be to make sure it can't slip or be accidentally moved to expose the gland. I wouldn't say that was the only option though.

Some might suggest that the boot doesn't have any guaranteed insulting qualities and so if a brass gland is used it should itself be enclosed inside an insulating enclosure to make sure it's not exposed within reach of the EV's earthing system.

Some propitiatory SWA glands have and insulting outer shell, which might be worth consideration for such cases. I have also seen pictures of metal SWA (ZEN?) glands with in-built isolation between armour and enclosure (but I can't say I've ever seen them offered for sale in wholesalers...). and the issue of metal parts of the two systems remaining within reach of each other might still persist even then.

   - Andy.

AJJewsbury said:

I think it's meant to be covered with the shroud/boot (the close up shows dotted lines each side, presumably trying to imply a cut-away to show how things are arranged inside the boot).

The shroud/boot can be removed 'without destruction' and is therefore not suitable for basic protection (Regulation 416.1). This is where I was going with 'cold shrink sleeving' (although appropriate heat shrink might perform similarly, it's just that when you're working on many of the sites I've worked on heat shrink needs a 'hot works' permit).

In my experience, the shroud/boot is only protection against water from certain directions (i.e. to meet IPx5).

Agree, the boot can easily be removed, A correctly sized plastic bodied gland is preferable.

M

A correctly sized plastic bodied gland is preferable.

I don't disagree at all ... (as per my earlier posts) but in terms of what the regs actually require...

The shroud/boot can be removed 'without destruction' and is therefore not suitable for basic protection (Regulation 416.1).

But where does it say that earthed parts of a different earthing system need to be covered with basic insulation? If we go down that route the sheath covering the armour isn't rated for insulation at all, so the problem then gets a lot bigger than just the gland. I thought we only needed to prevent things being simultaneously accessible - if it's covered it's not accessible. A properly fitted shroud shouldn't be easily removable, but I might suggest a cable tie around the cable to prevent it slipping to make sure. If you're wanting to make it foolproof then you'd need a way of stopping people running an extension lead from the other zone...

  - Andy.

all true - the problem is that the CPC from the wrong zone is not just a CPC, but a part introducing a potential. But if it needs basic insulation, maybe argued.

Now there are not enough accidents to worry about really but in principle there is a risk - its why we do put insulation on the  neutral which is also at the 'wrong' earthy potential.

M.

AJJewsbury said:

But where does it say that earthed parts of a different earthing system need to be covered with basic insulation?

It doesn't. However, BS 7671 requires that simulatenously accessible exposed-conductive-parts are connected to the same earthing system.

A permanent barrier (or enclosure) ... perhaps insulation ... could be used to prevent simultaneous contact, depending on the circumstances.

However, a consideration is also that we need to protect electricians going about their work. A brass gland won't do this, unless insulation (or some other form or barrier or enclosure) is used.

However, a consideration is also that we need to protect electricians going about their work. A brass gland won't do this, unless insulation (or some other form or barrier or enclosure) is used.

Careful... same issue could arise during the process of connecting a bond to an extraneous-conductive-part or the cable to the MET or or the MET to the DNO's earth terminal - and we don't insulate any of those....

   - Andy.

AJJewsbury said:

Careful... same issue could arise during the process of connecting a bond to an extraneous-conductive-part or the cable to the MET or or the MET to the DNO's earth terminal - and we don't insulate any of those....

Careful indeed. Suitable protective clothing ought to be worn, particularly with the risk of either diverted neutral currents or (and I wouldn't recommend doing it when he installation is energised, but to illustrate) protective conductors currents.

We are not, however, talking about connecting or removing bonding, but something else ...

AJJewsbury said:

I’d be interested to see the official guidance that you mentioned.

My memory isn't what it used to be, but I'll try to dig it out...

I'm still digging - I've found one reference in an old GN 8 that refers to "an insulated cable gland" (when supplying a TT'd outbuilding) but that wasn't exactly what I recalled and is open to interpretation anyway (it might mean a cable gland constructed of insulating material, or a brass gland that has insulation applied to/around it, or even a ZEN type gland). I'll post again if I can find what my ageing brain thinks it remembers.

   - Andy.

AJJewsbury said:

I'm still digging - I've found one reference in an old GN 8 that refers to "an insulated cable gland" (when supplying a TT'd outbuilding) but that wasn't exactly what I recalled and is open to interpretation anyway (it might mean a cable gland constructed of insulating material, or a brass gland that has insulation applied to/around it, or even a ZEN type gland). I'll post again if I can find what my ageing brain thinks it remembers.

Yes, GN8 (page 75) does refer to an 'insulated cable gland' (whatever that might be ... I'm sure I've never come across one.

In the railway and infrastructure industries, for this type of interface, it was common to see insulated gland adaptor ("extender" or "gapping") tubes, and appropriate shrink-sleeving insulation, in the following fashion, to prevent simultaneous contact:

I know you have commented on this in the past, "How do I test" later ... the only way would be to put an intermediate tail connector under the sleeving, and bring it out somehow into a suitable insulated terminal.

only way would be to put an intermediate tail connector under the sleeving,

Or to verify in the field where the tail  like that has not actually been done, perhaps a "vampire contact" * with a very sharp probe through/ under the end of the insulation, and if you are lucky a dob of mastic or something similar to fill in the pinprick and conceal the damage.

Plastic stuffing glands do have a lot to recommend them !

Mike

PS * in terms of 'vampires' I've seen the overhead chaps use the tip of a knife blade in a similar way to make a test contact to a single for polarity verification, though to be fair it was a good few years ago, and part of a very temporary hook-up where the underground cable had failed. Rather like the tales of the temporary supply cable coming in through a window or a letterbox, it is more about the duration of the risk being short, vs the risks being acceptable over many years, nor indeed an example of best practice..

only way would be to put an intermediate tail connector under the sleeving,

Or to verify in the field where the tail  like that has not actually been done, perhaps a "vampire contact" * with a very sharp probe through/ under the end of the insulation, and if you are lucky a dob of mastic or something similar to fill in the pinprick and conceal the damage.

Plastic stuffing glands do have a lot to recommend them !

Mike

PS * in terms of 'vampires' I've seen the overhead chaps use the tip of a knife blade in a similar way to make a test contact to a single for polarity verification, though to be fair it was a good few years ago, and part of a very temporary hook-up where the underground cable had failed. Rather like the tales of the temporary supply cable coming in through a window or a letterbox, it is more about the duration of the risk being short, vs the risks being acceptable over many years, nor indeed an example of best practice..