Exterior wiring underground and under render to wall lights

S.W.A starts at 1.5mm2. All joints are best left accessible. I hope that the void under the house floors doesn't flood. Think of water ingress as a possible problem.

It is best to get an electrician in first at the planning stage to avoid any expensive kukups.

Normally S.W.A cable needs to be correctly glanded and the armour earthed at the circuit origin, and in many cases correctly glanded at both ends to provide good earthing.

Here is one video on the subject. I prefer earthing nuts to banjos though.

www.youtube.com/watch

Z.

Then there's this.

https://www.youtube.com/watch?v=5XST0DkotYw

Z.

Is it ok to leave the SWA sheath un-terminated at the wall light?

Not ideal. You'll need an earth at the light (even if you happen to install double insulated lights now, regs still require an earth be present in case they're replaced later on) - while you could achieve that by using 3-core rather than 2-core SWA cable and re-purposing one of the cores as a c.p.c., you'd likely still be reliant on the armour being properly earthed (at least in the underground sections) - so you'd need a way to prove that during inspection & test - which means needing a connection at the light end to test it - especially if there's an underground joint.

You could gland the SWA into galvanised steel conduit (BESA) boxes, set flush with the render - not entirely ideal as the glad then becomes inaccessible (but no more so than a joint in steel conduit in the same situation, which is usually deemed acceptable). You'd also need reasonably deep render (or start cutting into the brickwork).

Depending on the exact situation, I might look for some unobtrusive corner where the SWA could come out of the ground, glanded into a surface IP box, then concealed cables run from there to the lights (in normal "safe zones") - that could be almost anything - even T&E with capping over should do - or something in PVC conduit if render depth allows - and then termination into individual lights should be a lot easier.

  - Andy.

Why can you not bury NYY in the wall cement courses rather than use SWA? You can stick with SWA underground, but convert to NYY for the final runs to the lights.

Have you considered solar powered light?

I don't want any visible cables or boxes so NYY to SWA would either be in a Wiska box on the wall or a resin filled joint underground. But is NYY allowed underground, even a short distance? To allow for cable replacement I don't want to fit the cable directly in the wall, so need PVC or steel conduit. I could use steel conduit, but then would need to earth it underground which I don't think is acceptable. Could use steel all the way I suppose!

Hi David, not considered Solar power. I'll have a Google.