SWA Cable Gland Adapter Piece

Question

Hello 
 Can anyone offer some help regarding the use of fabricated SWA cable gland adapter/extension pieces? 
 During installation works, our contractor has made off 2No 5C, 240mm2, SWA cables too short to reach the gland plate. 
 To avoid replacing the cables, they have site fabricated two "Extension pieces" from some 316 S/S to allow the cables to be terminated (shown below). 
 We have some reservations accepting the installation, therefore I am seeking some clarity on the following points: 
 
 Is this an acceptable installation method under BS7671? 
 What specific clauses in BS7671 would these pieces have to conform to (511.1?) 
 is there anything in the Regulations that would allow this installation to be rejected? 
 
 Thank you.

AJJewsbury · Accepted Answer

I don't recall a BS for "oops extension pieces" (to mis-quote Starrett's oops-arbors) - in which case 511.2 is probably the way to go. 
 In the first photo it looks to have been installed at a bit of a jaunty angle though ... which might make me suspect that the extra lengths involved are acting as a lever and putting more strain on things than would ordinarily be the case ... which if can't be corrected would make me wonder about 134.1.1 (Good workmanship .. and proper materials). 
 - Andy.

mapj1 · Answer

Normally on smaller cables one uses a short length of the same size conduit as the gland hole to do this, much as one would for pyrotenax cables. Modern way seems to be to waste a length of metal trunking and use a few inches of it or have an adaptable box with nothing in but the cores and a bit of wiggle length. 
 However, as this stuff is presumably about 3 inches in diameter and the glands will look like soil pipe fittings, so perhaps not at this scale. 
 So, first how well does it make electrical contact - would it handle the full PSSC? 
 Then, does it satisfy the environmental requirements of the location ? - looks not to be IP anything but I don't think the bare gland was IP44 either... 
 Third, Is it putting an excess strain on the gland plate or box ? - if so the cable fixings may need revisiting. 
 So probably could be OK, if done well, but of that we need to be confident. 
 Oh, also, why is there a machine screw sticking out the side ? 
 Mike.

gkenyon · Answer

Michael MacMillan said: We have some reservations accepting the installation, therefore I am seeking some clarity on the following points: 
 
 Is this an acceptable installation method under BS7671? 
 What specific clauses in BS7671 would these pieces have to conform to (511.1?) 
 is there anything in the Regulations that would allow this installation to be rejected? 
 The IP rating that could have been achieved by the original gland is now, sadly, not achievable. Are there any prevailing environmental conditions? Is corrosion prevention suitable? This kind of question is really difficult to answer accurately without seeing it "in the flesh" because we have no context, especially with such limited snaps. 
 At the end of the day, I'd be worried about the ongoing continuity of the SWA connection to PE - which it will need at least at one end (for safety, extraneous-conductive parts definitely here) but also perhaps to control touch-voltage at the other (or for other purposes). Also, from experience ... are there any other contractual requirements that might not be met ?

Aside from all that ... the "fix it r" option at this stage may well be a potted junction to extend the cable (depending on lengths of run) ... which might prove a nuisance in the future.

broadgage · Answer

"5 core" cables suggests one core as the earth, together with three phases and a neutral. If this is so, then an earth core reduces concerns about the fault current withstand of the extension pieces.

lyledunn · Answer

Michael MacMillan said: Is this an acceptable installation method under BS7671? 
 What specific clauses in BS7671 would these pieces have to conform to (511.1?) 
 is there anything in the Regulations that would allow this installation to be rejected? 
 It&rsquo;s amazing sometimes how a contractor&rsquo;s cock-up can become someone else&rsquo;s problem. I am usually sympathetic to contractors, been there and done it, so to speak, but I would stand my ground on this one. Grand if there was a specific technical reason to reject it but for me it is a contractor mistake that fails to meet the design intent. When the contractor leaves site, the client is left with something that was never intended. The contractor will have forgotten his mistake in short shift, but the mistake will be there for the whole life of the installation. Who knows, there may even be a query raised at the first periodic inspection, which the client will have to deal with. Why would you accept the bother? What technical argument could you put forward, for example, to a spark who leaves the socket outlets and other accessories at different heights above the worktop in a new kitchen?

SWA Cable Gland Adapter Piece

Join us to get the best from IET EngX.

Community Rules & Guidelines