3 inch x 2 inch or metric equivalentremember you're speaking to someone who's knowledge of timber is limited to that it comes from trees... by 3x2 are you referring to the wall stud, and it that a standard size for wall studs?
no just drill across through the studs in the center with a 20 mm auger giving a depth deeper than 15 mm from the outer boards for cables either run them horizontal or vertical from the sockets or switches and thats the safe zoneJust run it through the studs as they've usually no more than 400mm apart. I've put metal plates across all the studs where cables go through in my extension as I'm never going to remember where they all run!
@brightspark do you mean 50mm deep in the wall?
going just vertical only is old hat now regs have changed . you can now run the cables horizontal as well. saves a lot of cable and time. everything must be rcd protected though now . https://www.google.co.uk/search?q=safe+zones+for+wiring&sxsrf=AOaemvIeZbZ2e8qj2pBLxYEhjLwUFG2MFw:1643223394152&tbm=isch&source=iu&ictx=1&vet=1&fir=SORkVvQ6Lyr2oM%2CUiluuOXPOpPizM%2C_%3BGwufrT8ccFXK7M%2CUceishAVcZqT-M%2C_%3Bw3PUL1NPTTcIJM%2CUaeKVDNeUw66oM%2C_%3B3Ttb1iTIgQgiLM%2CUiluuOXPOpPizM%2C_%3BatqtT5NtkaPEWM%2COXHdnpmmQjU-fM%2C_%3BAecuAqsPFmaTjM%2CoJdym2mvqDcSlM%2C_%3BDi_4o3bHlwQWTM%2C3Xq29TReXuIAMM%2C_%3B82AH8x7whq5tzM%2C5fJii4LvwhzGiM%2C_%3Bt2DWolCrjpW-_M%2CUaeKVDNeUw66oM%2C_%3Bo-xxlSGnxRI3zM%2CJQjcHsfW9LjLeM%2C_%3B1e0etxGBsxdozM%2CnTdtiKCk10yGVM%2C_%3BVDSoUyFNIy__BM%2C8cEufiToU7mp7M%2C_&usg=AI4_-kTCwrYv-uLOICLE7jh5JlZDPPsXyg&sa=X&ved=2ahUKEwjAnseVjND1AhUREcAKHZihBJUQ9QF6BAhHEAE&biw=1228&bih=640&dpr=1.5#imgrc=atqtT5NtkaPEWM&imgdii=VDSoUyFNIy__BMThose cables are running horizontally yes?
Isn't that a bit of a no-no?
My mate whose a (good) Sparks always said to keep that you should always have your cables vertical in the wall.
(Many years ago I used to do some weekend work with him doing cabling & first fix.... and we used to drill a hole where the outlet was going and then fish to draw the cables in from above.
I'd not have lot anyone make that total horlicks in my house tbh.