Unsheathed single cables in domestic conduit

[CJF]

Hi All,

Recently moved to a 70s bungalow, and found to my surprise (and pleasure) that all the original wiring is in oval plastic conduit plastered into the walls, and routed up to the loftspace. This means that I can replace/modify cables and circuits as required without cutting channels - great.

However, as was often the case at the time, most of the rooms originally had one centre light, controlled by one switch. The conduit for these switches is large enough for just one cable, and I would like to increase the available circuits for wall lights etc. I know that the use of PVC covered singles in conduit is common in commercial wiring schemes, so I am considering stripping the sheath on three and earth cables back at the point of entry to the conduit, running the cores through the conduit as they are, and thus gaining more circuits to the switches/dimmers. I am aware that I will have to either sleeve the earths throughout the conduit, or (less conveniently) change to yellow/green PVC covered singles at the point of entry. The conduits extend above the ceilings by a couple of inches, and I can sleeve the stubs with larger conduit to give some extra cover at the point where the cables become unsheathed

Any thoughts on how conventional/sensible/legal this might be. In practical terms, and if done with care, I can't see any real disadvantages with doing this - the conduit is all vertical/horizontal from visible fittings, and the mechanical protection from drilling/nailing etc will not be significantly different with or without a sheath

I am, of course, only extending/altering existing circuits in order to be compliant with Part Pee.....

Charles F

[Andrew Gabriel]

Run triple and earth down to the switches, which enables two lights to be separately switched. Obviously, you can't use simple loop-in wiring if you do this.

[Owain]

(a) oval plastic conduit may be intended for use with sheathed cables and may not be compliant with the BS for plastic conduit for use with singles.

(b) T&E with the sheathing removed may not be compliant with the BS for singles intended for use in conduit

(c) Sleeving long lengths of uninsulated cpc will be difficult or impossible.

I'd suggest buying some reels of singles cables rather than faffing with stripping T&E.

If you don't want to disturb decorations, you could also use pullcord switches (also available as dimmers - see Dimpull on TLC site) or wireless switches.

Owain

[CJF]

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Thats what I'd normally do - but these conduits are quite tight, and I can't quite get three and earth down them (I've tried...) Hence the other solution. Everything is already wired in junction boxes already - which I prefer- so that's not a problem.

Charles

[David Hansen]

On Mon, 4 Jun 2007 07:35:19 +0100 someone who may be "CJF" wrote this:-

Cut them off at a suitable place. Install an adaptable box on top. Install terminal strips in the box to make connections. Feed singles along the conduit.

[Andrew Gabriel]

[CJF]

Looks like singles then.... I should only need yellow/green and brown, as all the switch returns should be sleeved brown antyway. Thanks to all for your comments

Charles F

[meow2222]

That would work. But it still gives you limited control.

If you want greater control, another option is a single mains feed plus LV multicore control cable - or even very thin singles for this. Due to limited insulation the LV needs to stay contained within the mains stuff, not touchable. LV & relays give lots more control than 2 or 3 mains ccts.

NT