burying electrical connection in the wall

Why bring DIY electrics into disrepute?

e.g. if you leave a blank plate where the switch currently is, the backbox can house chocblock, or wagos, or barrel crimps whatever, your can "legally" go straight up towards the safe zone at the wall/ceiling junction, round to where you want the new switch and then down.

without seeing photos of the actual location, we can't tell, but there might be alternate "legal" routes depending on location relative to corners, other switch/socket locations ...

You need a "maintenance free" join then. Crimps and heatshrink would be my choice... wago also ok.

Without a visible plate just make sure you don't leave a live drop wire in the wall that will no not be indicated in any way.

Nooooo! How will anyone know there is a cable in the wall leading to where the switch was? I think there are two alternatives: fit a blanking plate to show where the cable runs are, or (and the approach I would take) connect to the switch cable in the floor void and drop a cable vertically to the new switch. If you can't get into the floor void then make one or two small holes in the ceiling. Please DON'T do what you were proposing, it's not compliant and could cause injury.

The electricians who wired up my house when it was built in 1976 intended the thermostat to be at the bottom of the stairs, but when I bought the property 16 years later it was on the other side of the wall, in the lounge, with the wires going through the 3 inch cinder block partition wall. The cables had not been extended so must have been done ?at the request of the first owner.

The same conduit on the hall side of the partition wall also holds the lighting cables for the lounge but there was no indication that any cables were at that location.

FWLIW as a pessimist who does not live alone I'd avoid the issue by fitting 2 x 2-way switches ready for when I have to turn it round again :(

Is that metal conduit? If so it is exempt from the safe zones provisions, as you can't easily knock a nail into it or drill through it without noticing.

Probably with a pair of knickers.

Does anyone use metal conduit in modern (1970's) estate houses ?

Only a mental case would have used it through choice or have specced it.

I hate the stuff. I did two house rewires with it in lockdown.

Trust you to lower the tone.

Bill

Am I correct?

I used it (only one piece, but curved along one section), when I re-did our kitchen during lockdown - purely as the only way to get two lighting cables from the switch to the junction box, being unable to use the safe zones due to the staircase being in the way.

As always yes.

Bill

That is normally my job...

To quote my daughter "This conversation got weird quickly" SWMBO "What do you expect, daddy is in the room!"

Exactly. The lighting and thermostat cables in my house were in standard oval plastic conduit but in the hall with no indication that they were hiding just below the plaster because the cables went through the partition wall into the lounge.

I suspect the intention was to have the stat mounted in the hall at the bottom of the stairs and this would have alerted anyone planning to drill or hammer fixings into the wall above it that there could well be cables there. Wifey of first owner probably objected and had it moved by the builders.

When I rewired my brother's ex-council house 15-ish years ago, we discovered a socket at the back of the fireplace - fed by a cable dropped down the centre of the chimney breast. Exactly where you'd wallop a nail in to hang a picture.

That would be ironic if it was a picture of the M-i-L

I helped a neighbour rebuild his kitchen once. We were looking at re-tiling the splash back around the sink, and I noticed there was an odd bulge in the plaster that would through the tiles out of line. Hacked away at it a bit and found a 5A junction box with three cables attached that had be buried in the plaster (which was evidently not quite deep enough to fully hide it!)

(it was not long after that he asked me to re-wire the whole place!)