workshop electrics

Help Support




The timber is on order and I plan to start building my new workshop over the bank holiday (hammer) Before I line it however I need to think about the electrics. Thus could someone help with the following simple questions as I havent had large tools before and want to make sure I dont have to re-wire it in a years time :roll:

Firstly is a normal house type ring circuit suitable? I assume most tools simply come with a plug on the end rather than needing to be hardwired into the electrics - is this the case? I have only used hand power tools up till now so will be upgrading to a small bandsaw and possibly a lathe and jointer/thicknesser etc. No table saw yet but possibly in the future... :D

Secondly anyone any general advice on where to site sockets etc? Obviously above bench height all round the walls but is it useful to have one in the floor (shop is only going to be 10ft by 16ft) or run a wire down a joist and have one in the ceiling?

Finally, the roof and floor are going to be 18mm OSB over 2x4 timber, and the walls 16mm shiplap over 2x4 timber. I plan to insulate the walls with loft insulation and then cover this with either plasterboard or possibly a stronger sheet material such as 12mm ply internally. Would you recommend also insulating the roof in the same way or does this not make much difference?

Any advice gratefully received bofore I start building!



I'm about to do a similar sized workshop (when I have PP) and I plan to fully insulate it using the guidelines of the latest building regs as a basis. Most certainly insulate the roof and also consider insulating the floor. If you do it correctly you and your tools will be warm and dry!
As to the electrics - I use a 4mm feed to my existing workshop (the garage) that comes from a seperate 30A MCB in the house distribution box protected by a RCB. I decided to use a 4mm feed to fixed spur boxes rather than 2.5mm, as my saw and planer both draw around 16A when running, which would not be good for a standard 3 pin 13A type plug/socket arrangement. In the next workshop I think I'll put in a standard 13A ringmain for all the standard kit and then replicate the 4mm fed fixed boxes for the say and planer. You also mention the possibility of ceiling mounted sokets; I've got one a block of 4 13A sockets in a special fitting that hanges from a chain just above head height which is very usefull when sanding or routing in the middle of the workshop. Hope this helps.


Established Member
16 Apr 2003
Reaction score
Near Swindon, Wiltshire
You know that old saying that you will never have enough cramps? Well, sockets are a bit like that too. My advice, fit lots, in blocks of four at least, and in several places. I find a socket height of about 48" to be the most useful, but will certainly experiment with some ceiling sockets on my next reorganization. On the subject of electrics, I expect you will be fitting plenty of 5' neons too.




I'm not too clued up on electrics other to second especially what John says about putting loads of sockets in. Better than too few.

Just a point on 3 pin plugs and hardwiring. Most of the lightweight machines come with a 3 pin that obviously you just plug in when you want.
Bigger stuff such as the Kity 619 table saw, you have to hardwire. Well I did anyway!! Had to run a cable from the fusebox to the saw via a switch box thing! Bit like a cooker supply arrangement. This may apply to other bigger machines you buy later.

Always make sure you use RCD's. They will save you being electricouted!

Couple of points about your build.
Asssssuming its a shed, insulation in the roof is a good idea as much for keeping the heat out in the summer as well as the cold . Sheds get like furnaces when its really hot outside and roof ins. will keep you a bit cooler.

When you do the floor, make sure the floor joists are quite close together.
In the past I've assumed 18mm board will bridge quite big gaps. In fact to avoid the floor going "dippy" make sure the joists are about ideally 12" apart (centres)

Instead of ins. wool, you can buy poly. foam board in 8x4. Its very light to handle and cuts with a bread knife. It comes with a foil coat, buy it from B+Q Warehouse not small B+Q. its quite cheap. You can line the roof with it, just wedge it between the roof joists.

Hope this helps a bit



When I said "use RCD's" I meant RCB or was it MCB!!

I told you I wasnt up in electrics! I meant using the ones where the button pops out if soemthing goes wrong.

I reckon I average an electric short about once a year and evrything just goes off instantly.


You can not have too many sockets - e.g. how many battery chargers do you have? plus the radio & any heaters - and that's before the power tools :!:, but make sure that the expected total load on the circuit does not exceed the cable's rated power.

I ran 12mm armoured cable from a 45A breaker in my comsumer unit in the house to a consumer unit in the shed which has RCD plus 2x 30A & 1x 5A breakers. The 5A is for lighting and has a old computer UPS (battery backup) so that if power fails, the lights remain on whilst the fast spinning things slow down :idea: . I used 2.5mm for the cabling since I only use one piece of kit at a time & its all rated for <13A

Each 30A circuit is further protected by an emergency cut off circuit with red "mushroom" switches near every socket. I only need to momentarily press a single mushroom & the whole circuit cuts out and can only be switched back on by a reset switch at the control unit. They also have NVR type action if power is lost to the shed entirely, or the breaker trips.

I decided to build the cut-out circuitry so that I am always with half an arms reach :shock: of an emergency stop button and it works fine, although, I sometimes inadvertently trip the buttons mounted on the side of my workbench. The extra wiring involved is worth the peace of mind.

I designed & built the cut-out units myself for about £20 apiece, and will post details on my web-site if there's enough interest

As far as insulation goes, I have not (yet) got round to insulating the roof space yet, but have used fibreglass rolls in the wall cavities.


Cheers for the info Guys,

Seems a bit above just adding sockets in the house which is all I have done before, think I will call in an electrician at least for a quote and go from there :oops:

I can at least insulate the roof myself though :D


Latest posts