Best way to run cables in conduit

[Philip Saunders]

I have a 20mm steel conduit drop to an accessory box buried in the wall. It was previously used for lighting cables and had 2 x 1.5 t+e and 1 x 1.5 3+e squeezed into it. There is no actual conduit system installed - the conduit simply goes into the loft and ends. There is some kind of rubber grommet on the end to prevent chafing.

I want to re-purpose the box (dual single gang) with a 1-way light switch and a switched FCU to control some outside sockets.

This means 2 x 2.5 and 1 x 1.0 mm cables.

I don't want to put t+e back in the conduit, and I don't think it will fit anyway.

All the wiring in the loft is t+e, including the ring I want to spur from for the sockets.

Singles will obviously fit so I guess my question is what's the approved method of joining the singles emerging from the top of the conduit to the existing t+e? Would plastic conduit into a plastic surface box screwed to the rafters with the t+e entering from the other side, and wago or similar used for the join be OK?

 

[westward10]

The top of the tube would have to be threaded so a coupler can be fitted. Just entering it into an enclosure doesn't really give correct containment.

 

[Dartlec]

I have a 20mm steel conduit drop to an accessory box buried in the wall. It was previously used for lighting cables and had 2 x 1.5 t+e and 1 x 1.5 3+e squeezed into it. There is no actual conduit system installed - the conduit simply goes into the loft and ends. There is some kind of rubber grommet on the end to prevent chafing.

I want to re-purpose the box (dual single gang) with a 1-way light switch and a switched FCU to control some outside sockets.

This means 2 x 2.5 and 1 x 1.0 mm cables.

I don't want to put t+e back in the conduit, and I don't think it will fit anyway.

All the wiring in the loft is t+e, including the ring I want to spur from for the sockets.

Singles will obviously fit so I guess my question is what's the approved method of joining the singles emerging from the top of the conduit to the existing t+e? Would plastic conduit into a plastic surface box screwed to the rafters with the t+e entering from the other side, and wago or similar used for the join be OK?

Is it actually 20mm conduit? or is it the old metal piping that was put in for the original wiring, of which there are still plenty around - in which case it's probably not 20mm but some imperial equivalent.

If you're running cpc as singles too then there isn't a need to use the conduit as earth, though it may be at the switch end depending on how it's terminated.

The important thing is that the singles are in an suitable enclosure throughout their run. If you can get a plastic conduit bend onto the top of it with a good tight fit, then into a pvc box, that should be sufficient, though you need to ensure that it can't come off as insulation is placed back on it or movement occurs.

The rubber grommet on the end is even more important with use of singles, to avoid chafing, so you will either need to ensure it remains on or that no sharp edges can rub on the installed singles.

 

[westward10]

If you have enough tube exposed you could fit one of these, never used this before but I assume one end is threaded.
https://www.kernow-how.com/Products/conlock-conduit-accessories/CL20GA

 

[Philip Saunders]

Thanks all - I hadn't actually considered that it might not be 20mm I'll have to check. Building is 1980 so it's probably OK.

The end isn't threaded so the conlock adapter might be the way to go - I'll be using a separate CPC so it's only a mechanical connection I need.

A thought did occur tho - do the individual cores in t+e meet the specs for singles? Could I strip 1500mm of sheath off of t+e and run those 'tails' down the conduit, just sleeving the cpc where it's exposed at the end?

 

[westward10]

The cpc needs sleeving over all the exposed conductor but that can be done before it goes down the tube. I don't like the idea of stripping the cable and installing in such a way as they are not correctly contained.

 

[Lucien Nunes]

If the conduit is from 1980 it will be metric. I think the Conlok solution is ideal in this case (I don't like it generally). You could use the Conlok-to-threaded coupler liked by Westward10 to attach the male threaded adaptor a length of flexible conduit to reach a suitable location for your junction box.

 

[Philip Saunders]

If the conduit is from 1980 it will be metric. I think the Conlok solution is ideal in this case (I don't like it generally). You could use the Conlok-to-threaded coupler liked by Westward10 to attach the male threaded adaptor a length of flexible conduit to reach a suitable location for your junction box.

Thanks for that. That was my thoughts too. The JB will be pretty much right next to it so a short length of flexi will work well.