Removing conduit

[GaryS]

I have a bungalow which has all the wiring in the loft in metal conduit. I want to replace some of the wiring and conduit with T&E but it is not possible at the moment to replace the conduit and wiring dropping down to the skts and light swithes. Is it permissable fix a suitably rated connection box adjacent to the vertical conduit drop and connect the single cables from the conduit into it. If so, what is the max length the singles can be left unprotected.

 

[plugwash]

may i ask why you wan't to replace it with T&E

if the singles are old or rubber or too small or whatever than you can just pull new ones of the appropriate size through the existing conduit

as for the issue of joining singles in conduit to T&E just use chock block or crimps inside a conduit box

 

[GaryS]

The wiring was is at least 20 years old but is pvc. The main reason is that the conduit runs above the joists and I want to put flooring down. Another is that the cpc's are connected to the securing screws on the first available inspection cover, after the fitting they supply. Is this correct. Seems to me that this is not the best way the secure the cpc. The conduit is then used as the cpc. Loop impedance is about 0.6. Also the ring cpc (where run) is only 1.0 mm supplied from a 30A mcb. the type you can plug in instead of a rewireable fuse.

 

[plugwash]

earthing through conduit is not ideal but provided its done well isn't a real danger either

are the conduit drops big enough to pull T&E through?

 

[GaryS]

The conduit is big enough to pull T&T through, however, most of them have no play in the cable, suggesting a bent run or the ends of the wires are stuck in the plaster. Redecorating thriughout is not an option at the moment. Plan to replace the drops as I decorate each room.

 

[Lectrician]

What sort of conduit? threaded ends, or clamped ends?

 

[securespark]

If clamped which I suspect, then the joints will not be reliable enough to use the conduit as cpc.

You can't make omelette without breaking eggs. Maybe you'll have to bite the bullet and make small holes in the plaster to enable you to run T & E through.

 

[Lectrician]

Securespark, my thoughts exactly. Have seen small 16mm ish conduit used with clamp style tees, bends etc. Needs repalcing.

 

[GaryS]

All the conduit is 20mm (or whatever the equivalent was back then) with threaded ends.

 

[Lectrician]

Dont see that domestically very often. Is it bushed into the switch boxes in the wall well?? (to ensure earth continuity??)

 

[GaryS]

The light switch boxes are connected to the conduit but then the boxes are made from a heavier gauge metal than normal ones. The skt switch boxes aren't.

 

[Lectrician]

I dont see why you couldnt cut the conduit at the top where it enters the loft, the conduit would be earthed aslong as you earth the switch back box with your T+E cable. The cut end in the loft would ideally be bushed.

 

[ban-all-sheds]

Kopex do a quick'n'easy alternative to cutting a thread and fitting a bush:

Not sure of the size, though...

 

[Lectrician]

Yep B-A-S, that looks ideal.

 

[GaryS]

Thanks, the plastic bush looks ideal for the drops I can pull T&E through. But for the drops that have to remain in singles,(for the time being), will I'll still have to connect some kind of terminal box to the top of the conduit to protect the cables between the conduit and the T&E connections? Or is there an allowable distance the singles can be left unprotected.