How to get Electrical Box Out ?

[Spinny]

So I need to move an electrical box about 40mm to the right - see photo.

 

The box is loose but how do I get it out without damaging the cables ?

[crispy_wafer]

Multitool with metal blade and cut each side of the cable into the grommet holes on either top or bottom whichever is easiest one cable out then the box will come out and the other cable will feed out.  Or cut away more plaster and slowly tease and feed the cable backward into a U shape on the outer side of the box and pull slowly and gently try not to snag the cable and hope the rubber grommet protects against the sharp edges. There will be some making good required but that’s par for the course I’m afraid!

[MPx]

Agree - take the hit on making good and just knock out a bit more plaster/wall - then you'll be able to carefully feed the cable back as you tease the old box out.  If its just a 40mm move, there'll be a sizeable bit of filling around the new box anyway.

[Nickfromwales]

+1. Lots and lots of small gentle taps with a claw hammer, to turn the plaster to dust, and let it fall away as you gently follow the cable. Don't use a chisel, as that can damage the cable if it turns or isn't at the same depth etc.