Terminating SWA into the back of a plastic box

A technique I have used is to include a loop, where the cable changes direction by 180 degrees. That way you have access and total length is not critical where the loop can be adjusted.

Another technique I have used is to terminate SWA into a metal junction box and then carry the conductors and a new earth conductor connected to the armour onwards in trucking into a socket.

I'm not sure why you don't fit the final socket now?

Ideally you will need a gland of some sort to terminate the SWA somewhere. If you are isolating the armour at that end and not making connection to it, then you could get away with a plastic gland.

(Normally you will need a gland to allow adequate fixing and restraint of the heavy cable)

As this is outside you will want a waterproof termination of the cable - even if it is "inside" the post.

What length of spare cable do you have to play with?

You could have a JB on the back of the post, and transition to something easier to work with like hi-tuff. Clip that up the back of the post and then take it into a hole though the post into the back of your enclosure. (with the through hole at an angle that would encourage water not to run into the post)

You could also bend the SWA into a hole if it is not too thick and you angle/bevel the edge of the hole to create enough radius.

Here is an example where I took an extension from a side of a wall mounted socket and wanted to feed it through the wall. I drilled the through hole at an angle and chipped away some of the edge on the inside of the bend to allow a larger radius turn:

You would normally come through a wall and then into the side of a wall mounted box with an appropriate gland.

As much as needed :-) I haven't terminated the other end yet, so can pull some slack through. I want to leave slack anyway for future changes.

I think that's probably the best option. JB in rear of the post, then thread the cores through (I want to avoid jointing it) perhaps in some kind of conduit for protection (I have some white plastic 20mm that may do it). If I can find a box big enough I can coil some slack of the cores in the box for future use. Seal up both ends of the conduit with silicone. Perhaps some kind of gland or grommet to secure the conduit and waterproof the rear.

Would the SWA just poke through the brick or should there be some kind of cover? I've seen through-to-down right-angle covers for aerial cables and similar, but the bend radius of those would be too much for SWA.

Theo

Gland it into a galv through box and just take the inner of the SWA unsheathed out the other end of the box through a stuffing gland up to to the socket?

Hmm, would a 20mm gland screw on to 20mm conduit boxes?

Rather than taking the bare cores, take the cores still in their bedding layer as one "flex", and only strip back the bedding once into your socket enclosure.

I have not seen a cover used like that (they are popular with the less skilled aerial / telecoms fitters since they can blast through the wall from the inside with their SDS, spall of a massive "exit wound" and then cover with the plate.

Normally I transition using a surface mounting box of some kind - a waterproof JB[1] to terminate the SWA on the outside, with a normal exterior gland into the box, and then drill through the back of the box through the wall and use regular T&E or whatever.

That's what I'd do, but I don't think the bedding offers any mechanical protection, it's just to make the SWA bend without buckling. Plastic conduit gives it a bit of protection.

Yep, I have some of those :-( Particularly galling when you don't actually need the cable any more but the exit wound remains. Both before my time, but the trail of blame leads to Sky and Openreach...

(OR didn't even bother fitting such a cover)

That works if sockets are allowed. If it's say a run between a main CU and a shed CU then that's less good to have a random socket in the way. It does mean the box on the wall has a purpose though, not just a blank box.

Theo

Unless you are using SWA of a very large diameter the 20mm gland should be fine. There are two sizes to accommodate different range of SWA diameters. The conduit box has a M20 thread to match the gland.

ARW's suggestion, close to mine, is to use:

where you carry on the inner sheath containing the conductors through a standard gland:

If you place your box on the location of the hole through the post, the SWA can run up the back of the post into the side of the box using a normal SWA gland. You then take the cores plus bedding through the back of the box, though the post, and into your socket box. In the socket box you strip the bedding to expose the cores.

Alternatively you can SWA gland into a box, then compression / packing gland the bedding out of it. Small drip loop on that and into the hole in the post. Minimal exposure of the cable without armour.

The socket does not need to be fed directly from the sub main, it can initially serve just as a way to get the SWA submain connected, and fed to the next CU. YOu can then have a circuit that originates in that CU which powers socket.

i.e. here would be two internal cables to the socket. One to take the sub main to the CU, and the other to connect the local circuit to the terminals of the socket.

That's about what I wanted to say but did not have time to type it all out in detail :-)