SWA glanded in a plastic stuffing gland

Hi Andy 

This is true, then other design considerations would need to be made, as this would be outside of the scope of the original question where the charge points are connected to a separate OPEN device in a TN System. 

George Hancock said:

My opinion would be to use a CW gland at the EV charge point and the insulating gland at the OPEN device this way in normal working circumstances every thing is earthed via the main incoming earth, then in the event a OPEN fault the supply to the EV charger is isolated including the SWA and CW gland as this is now connected to the load side of the OPEN device.

But in many cases the O-PEN device (or RCD if it's being TTd) is integral to the charge point....

   - Andy.

Guessing why another electrician has done something will leaving you in whirlwind of three things: was it done with some logic, was it pure laziness, or ignorance to what should have been done, if we give the original installer the benefit of the doubt, their logic could have been, they did not want to use an insulating gland as this would make the gland its self an exposed conductive at the EV charger with the SWA connected to the buildings main earthing system. a problem if the supply earth is PME I am assuming it is based on the use of a OPEN device. 

Meaning in the event of a OPEN fault the charger would be isolated but the gland could still be an accessible earth path from the MET and true earth posing a significant shock risk to anyone that came in Contact with the gland for example any one investigating why the charge point is not working in a PEN fault.

If this was their logic the use of the dome top gland isn't a bad idea but it isn't the right idea.

My opinion would be to use a CW gland at the EV charge point and the insulating gland at the OPEN device this way in normal working circumstances every thing is earthed via the main incoming earth, then in the event a OPEN fault the supply to the EV charger is isolated including the SWA and CW gland as this is now connected to the load side of the OPEN device.

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..

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.

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.

AMK said:

The SWA armour should be trimmed back beneath the cable sheath within the plastic gland to ensure it remains inaccessible.

Given that a tug on the cable (unless there's a cable restraint) can remove it, and we know sheaths and insulation do move slightly ... It does seem like it may be OK, but the devil is in the detail.

The issue regarding pulling the cable with a stuffing gland is why in rail and airport infrastructure wiring, we used to use use plastic gland adaptor tubes, and sleeving). This is not new ... I'm going back to the 1990s.

AMK said:

However, current discussions suggest that this approach may no longer be considered sufficient ?

Well, the information in this thread is out there now, so that approach is perhaps not 'state of the art'

It wasn’t that long ago, in 2017, when professional guidance stipulated that at remote buildings, the SWA cable should be terminated at the remote distribution board or consumer unit using a plastic stuffing gland, rather than the conventional metal SWA gland. The SWA armour should be trimmed back beneath the cable sheath within the plastic gland to ensure it remains inaccessible. However, current discussions suggest that this approach may no longer be considered sufficient ?

AMK said:

Hi Graham. Would Providing a warning label on the enclosure to alert personnel of potential dangers.

Yes, but the CDM Designer would be advised to follow the Principles of Prevention ... and Hierarchy of Controls.

Under the Principles of Prevention, 'combat risks at source' is number 3 on the list ... providing instruction is the very last item. It is reasonably practicable to combat this risk by providing inexpensive insulation (although a warning notice of the folly of its removal without due consideration might also be practicable).

Under the Hierarchy of Controls, we should consider, in the following order:

1. Elimination (physical separation)
2. Substitution (why have two earthing systems in the first place?)
3. Isolation (provide insulation or barriers as discussed)
4. Engineering controls (possibly not relevant here)
5. Use of PPE (and this would follow warning if you've not isolated the hazard, and would require warning signs).

Hi Graham. Would Providing a warning label on the enclosure to alert personnel of potential dangers. This warning label serves to remind electricians and other personnel that, despite the requirement of a tool for lid removal, there remains a risk of exposure to live parts, such as the brass armour termination inside the enclosure. This is similar to the expectations when dealing with terminations that do not meet IP2X standards, where direct contact with live parts is possible.