repositioning a lighting conduit and switch

brianivor · 31 May 2010

I need to move a recessed wall mounted light switch about 250mm sideways to make way for a new doorway I am having cut in the downstairs wall.

I have had the floorboards up in the room above and find the existing switch wires run down an oval metal pipe to the lighting switch.

I plan to extend the wiring by means of a junction box screwed to a nearby joist with new cable from there to the new light switch.

Can I use plastic conduit in the new wall channelling or will I have to use a metal conduit as before and, as I am only moving the position of the switch, can I do this myself legally? (I am a competent DIY enthusiast)

Thank you

1john · 31 May 2010

you don't need to use a conduit at all but if you like to then PVC is fine. best bet is to pull the wire out and relocate it as it is if there is enough slack, failing that then replace the entire length from where it originates as adding an unaccessable junction box is not permitted by the regulations.

ColJack · 31 May 2010

depending on where this light switch is then you'll have to notify the LABC or use a Part P registered sparky..

more info needed.

RF Lighting · 31 May 2010

First of all, any screwed connections must remain accessible for inspection, testing and maintenence, so if you can not get enough slack on the existing cable by maybe being able to pull some length back on it or similar, and have to extend the cable, the joint box must be accessible when the work is complete otherwise you should use a different method of extending the cable, or better still, replace that piece altogether.

Is your lighting circuit proteced by an RCD? This is only likely if you have had your house rewired or your CU replaced in the last 2 years or so.

If it is not protected by an RCD then you either need to add an RCD to the circuit, or run the new switch drop in either earthed steel conduit, or use a cable type which incorporates an earthed sheath such as flexsheild or similar.

brianivor · 31 May 2010

The existing light switch is on the entrance hall side wall about a metre from the floor and a metre from the front door. I don't think there is enough slack to reach the new switch position without extending the cable.

I would prefer not to have a blanked off junction box higher up the wall (above the new light switch position)

The hall wall in question extends up to form the wall of the room above: perhaps I could recess the "accessible" junction box low down on the wall of that room? are there any other ways round joining the cable?

ColJack · 31 May 2010

replace the cable..

is this a 2 way light switch by any chance?

if it's not, how many of what cable goes to it?

if it's just one T+E then it's a simple thing to pull in new from the light..

brianivor · 31 May 2010

The switch is for a single light in the hall ceiling. not two way.

Examining the interior of the light switch a moment ago shows a metal box with a grey sheathed pvc cable from which extend a red and a black wire.

sparkwright · 31 May 2010

If you must join the cable under the floor you can use insulated crimps.

You can do the crimping joint in a plastic enclosure, or cover with heat shrink. Don't leave the crimps uncovered.

Be sure to use the right size, probably red ones.

Use a proper crimping tool - I'm sure someone will send the two photographs...

sparkwright · 31 May 2010

brianivor said:
The switch is for a single light in the hall ceiling. not two way.

Examining the interior of the light switch a moment ago shows a metal box with a grey sheathed pvc cable from which extend a red and a black wire.

No earth wire in the cable?
It may be cut off...
Any earth wire at the light fitting?

Use conduit in the event of a re-wire in the future.

ColJack · 31 May 2010

brianivor said:
The switch is for a single light in the hall ceiling. not two way.

Examining the interior of the light switch a moment ago shows a metal box with a grey sheathed pvc cable from which extend a red and a black wire.

then it's a simple job to change it..

the hard part is getting it down to the switch, but since you're moving it that's not an issue..

get the floorboard up by the switch drop ( which it sounds like you're already done ).. which way do the boards run with respect to the light and switch?

brianivor · 31 May 2010

So many suggestions! thank you.

The idea off pulling a new cable through from he light fitting sounds the most regulation friendly - it just depends on whether the existing cable is trapped and wont pull through.

I like the idea of crimping - if the cable where crimped was housed in a plastic terminal box would this meet all regs?

The cable to the switch seems to be just twin cable - the existing metal cable does not appear to be earthed (bonded)

sparkwright · 31 May 2010

You may be able to fish a new cable from the light to the lifted floorboard.

This is assuming the existing switch cable goes to the light fitting; and not a hidden junction box as was often the norm once.

brianivor · 31 May 2010

Thanks to you all - I guess I will try some of your suggestions and will return to the Forum if I get stuck!

Taylortwocities · 31 May 2010

ColJack said:
depending on where this light switch is then you'll have to notify the LABC or use a Part P registered sparky..

more info needed.

It is in the hall so you can do this work yourself, without nofifying anyone (except this forum, of course!)

brianivor · 31 May 2010

Thanks to you all - I guess I will try some of your suggestions and will return to the Forum if I get stuck!

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repositioning a lighting conduit and switch

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