I wish to install sockets 'flush' to the wall in my workshop / garage.

The inside wall is timber studding filled with insulation and covered with chipboard.

Am I allowed to use plastic 'plasterboard boxes' for mounting sockets etc. on chipboard ?

also if the insulation is polystyrene you MUST use conduit

soft pvc (cable) is adversely effected by polystyrene
ridgid upvc (conduit) is not

Hey Lee, if it's possible running the cable in round or oval conduit will be a better outcome, you can run 2.5mm twin cable for a ring in this situation, further allowances would have to be made if you ran the cable directly in the wall, rather than just in conduit in a thermaly insulating wall.

Get some 20mm round conduit and run all cables in this if you can, then a 32A rated ring circuit would be acceptable  

Easiest way to do this is to dispense with trying to 'hide' socket/accessory back boxs and surface mount everything instead - if it is a workshop, then it shouldn't really matter what can be seen.

I'd go for 2"X2" Galvanised trunking all the way round at or above head height, then drop out of this with either 20mm plastic or steel conduit to surface-mount metalclad accessories.

Dead easy, less fiddly, and you can chop and change things quite simply. Also, you can run single-insulated cables evrywhere, which is much cheaper than double-insulated stuff.

Also, it'll most likely last forever!

TT

doesn't mean you can't put metalclads on flush boxes

TT gets my vote, you should see my garage

I love industrial, give me some 400x400mm galv trunking and some nice large cables to play with and I will be as happy as a...............umm?............not sure what!

Yea, i like 2x2 galv, with a galve coupler drop to a socket (below).  Use the same trunk to tube up and over to the lights etc.

Bit OTT for a domestic garage maybe??

used 400x400 last year on a job, havn't since used it

to increase trunk from one size to another??  or teeing a smaller size from a large size??

2" galv couplers and bushes are best for larg DB boards.

If the board has a removeable top gland plate, this can be removed, and the exact same size hole jigged out in the trunking, use grommet strip where they meet, or better still, a piece of paxoline sandwiched between the two, with the hole in the paxoline cut about 10mm smaller all the way around.

Run it down the wall then tee into a horizontal piece across the top of the board, then as Lectrician says either use 2" bushes with either couplers or lock rings or cut a oval slot out with paxoline sandwiched in between the trunking and the top of the board

Yep you can get tee joints with a flange so you can spread the cable out into the horizontal trunking

Yea, Tee in to a horizontal length, or right angle it to a horixontal length.

You can buy the bends, or fabricate them using pop rivets. (best to ensure if you fabricate, that the trunking has one side continuous, eg, uncut.  This ensures continuity).

If you buy bends, ensure you use atleast one earth link across the join, the trunking manufacturers make links to fit where theie screw holes are.

Paxoline is hard to get nowadays, and couplers with 2 bushes are a better job.

Dont forget to supp bond the trunking from the fuseboard

And use round head screws to fix the trunking home, not counter sunk

And, not many people seem to realise, if you cut the trunking lid, and the cut comes in a bad place, leaving the trunking lid buckles to far from the end.....you can get additional buckles that you can drill in

Dont know if they make bellmouth flanges anymore, I think you may have to take some metalwork classes