Moving light switch from one side of a door to another

Hi, hope someone can help, either in terms of advice or giving me an idea of whether I need a decorator, a spark, or both. And what it would cost.

Wife has decided that door into spare room needs to be rehung, before fitted home office goes in. So the light switch needs to be on the other side of the door.

As far as I can work out, I need to drill and chisel a space for a new mounting box, then drill/chisel upwards to create cable space until I get to door height, then drill/chisel across the top of the door until I'm directly above the old mounting box (probably a good idea to turn the leccy off first!) Then I need to find the cable in the wall somehow, cut it, splice in more cable with some kind of gizmo that can sit in the drilled channel, fit the cable to the new box and replaster over all the drilling.

Does this sound roughly right? What will go wrong? Am I missing any obviously better ways to do this?

TIA

If you dont want it to look nice, thne the quick and dirty method is surface trunking run round door frame to old switch position and a join behind a blanking plate, or even surface wiring nailed to door frame if its not likely to be damaged.
But if you do want ot bury the cable, then a number of points to note:-
If you can get to the cable from above (loft or lift an upstair floor board) you can save the hassle of the sideways chase, just cut up to the ceiling. Check the reference section for picture of the permitted zones. Cables need to be where they can be expected, otherwise there may be an accident at a later date
If there is any chance of a cock-up, then bury oval conduit in the wall and plaster over that, or a similar plastic tube, so the wire can be re-threaded later once cut too short...
Not a good idea to have a joint buried in the wall, much better to have a junction box either on the ceiling or above it .
If you dont already have one, buy a cheap SDS drill or borrow one - with the chisel attachment it makes mincemeat of this sort of job, and is much less dusty than a whizzer (though still spectacular.) If the wall is breeze block, watch you don't go right through !!

If the wall is papered it may be possible to slit the paper (stanley knife)and peel it back far enough to be undamaged, so once you have replastered it can be cut back.

UselessFatBloke said:

Does this sound roughly right?

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No.

What will go wrong?

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You'll contravene a number of wiring regulations. You'll have cables running where they should not, which is dangerous, and therefore in contravention of the Building Regulations and therefore illegal.

See http://www.niceic.org.uk/downloads/C5-43.pdf

http://www.niceic.org.uk/downloads/concealedcables.pdf

Am I missing any obviously better ways to do this?

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You need to run a new channel straight up the wall to take a new switch cable up into the ceiling/floor void and to the light fitting.

If you don't have access to the wiring from the floor above then you've got problems. You'll have to cut holes in the ceiling for access, and depending which way the joists run you might have to drill holes in them. Then you'll have to join the cable onto the old switch cable. In theory such a junction box should be accessible for inspection, but many aren't these days, and it's not a major sin. Use a proper JB not choc-block, and make sure the screws are tight.

You could adapt your plan and have the horizontal run of the new cable very close to the ceiling, as per the diagrams in those links, but if you are planning to bury the join under plaster you can't use a junction box or choc-block, you'll have to crimp or solder it, and waterproof it with self-adhesive shrink wrap sleeving. Crimps, BTW, must be applied with a proper ratchet crimper, not one of those cheap squeeze-n-hope jobbies that car accessory shops sell.

ban-all-sheds said:

[squeeze-n-hope.

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Sounds like my adolescent years!!

Thanks for both the detailed answers! Very helpful. The coving is a quite ornate 30s job, and I don't want to bodge it by going through the ceiling, so chasing sideways very close to the ceiling sounds best.

what about just leaving the old switch in place and doing a two way setup?

avoids most of the wire routing problems (just run straight up from the switches and close to the ceiling horizonally) and avoids any need for joining cables

also means if you decide to put the door back the way it was before you don't need to undo anything.

plugwash said:

what about just leaving the old switch in place and doing a two way setup?

avoids most of the wire routing problems (just run straight up from the switches and close to the ceiling horizonally) and avoids any need for joining cables

also means if you decide to put the door back the way it was before you don't need to undo anything.

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Sorry if this is a silly question, but wouldn't that still mean either going through the ceiling coving, or intersecting with the cable going down to the existing switch?

UselessFatBloke said:

Sorry if this is a silly question, but wouldn't that still mean either going through the ceiling coving, or intersecting with the cable going down to the existing switch?

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Well - yes and no...

Check the For Reference topic for the wiring of 2-way switches....

UselessFatBloke said:

Thanks for both the detailed answers! Very helpful. The coving is a quite ornate 30s job, and I don't want to bodge it by going through the ceiling, so chasing sideways very close to the ceiling sounds best.

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just remember that if you do run it along the ceiling, it must still be within 150mm of the ceiling, not coving

You could drill upwards behind the coving - i.e. leaving it intact, and the drill still emerge above the ceiling. A 22mm SDS drill would do.