Power to Workshop

[k2]

Hi,

I am making a workshop/outhouse at the back of my garden, i will be adding an MCB to the main CU then running a SWA around 50m to the workshop then adding a RCD to the workshop,

I want to add 4 Lights and around 6 sockets 2 mainly for power tools (Bench grinder and a welder) and the rest for TV Games console etc.

Could i get any suggestions on the size of the SWA and MCBs RCDs


Thanks

 

[nickjb]

TLC have a good calculator. If you planning to run a welder 50m away then it will be pretty hefty. You need to notify building control before starting if you are doing it by the book.

 

[RF Lighting]

16.0mm² SWA, and you want to be using a HRC fuse for this supply, not a circuit breaker, but your electrician will know all this.

 

[ericmark]

Personally I consider shed power in general drops into two groups.
1) Under 13A
2) Over 13A
With the under 13A group you can supply with a FCU and use a switched FCU for lights if not already RCD protected you use a RCD FCU and as a result cheap.

With over 13A then in the main work requires registering with LABC and it requires a consumer unit in the shed and very careful calculations as to cable size and also of course earthing methods need considering.

Not saying you should not consider earthing methods with 13A but less of a problem.

At 13A you will get away with volt drop which is most limiting factor with 4mm² SWA cable as you go over 13A then the cable will need to be heavier. There are loads on calculators on the net to work it out I used one I made earlier in true Blue Peter fashion and get volt drop to 6.3 volts with 4mm² cable and for lights limit is 6.9 volts.

 

[ban-all-sheds]

With over 13A then in the main work requires registering with LABC and it requires a consumer unit in the shed.

Yes and no. Could run a 16/20/32A radial to the shed for sockets & still use an FCU there for lights.

 

[JohnW2]

With over 13A then in the main work requires registering with LABC and it requires a consumer unit in the shed.

Yes and no. Could run a 16/20/32A radial to the shed for sockets & still use an FCU there for lights.

Indeed. There is usually no 'need' for a CU in an outhouse, although if one wants RCD protection there (rather than at house end), a mini-CU is often the simplest solution. From the notification point-of-view, it sounds as if the work is already notifiable (CU or no CU), since the OP wrote...

...i will be adding an MCB to the main CU then running a SWA around 50m to the workshop then adding a RCD to the workshop, ...

... aka a 'new circuit' (non-contentiously, by anyone's definition, I would think).

Kind Regards, John