socket in shed, only got a 10a feed

underdog · Nov 29, 2010

ive got a 1.5mm fed from a 10a mcb feeding 4 flouresents in the shed and would like a socket for a heater. the way i think it should be done would be to fit a fcu with a 10a fuse and then a socket from the load. obviously there is a risk of some one plugging a 13a appliance in so i would lable the socket 10a max, which would limit it to a 2300w max appliance.

is this a bad idea or against regs? the only other way would be to dig the garden up and replace 1.5 for 2.5!

malcolmsanford · Nov 29, 2010

Depending on what cable it is and on the length of the run, that 1.5mm^ say if it was SWA could have a 16amp protection device, if it was a really short run it may even go to 20amps. So the first thing is to calc the actual load that cable can take and see where you are.

So for argument sakes let's say you can uprate to 16amps. I would then fit a small 2 way enclosure fitting a double isolator with a 6amp protection device for the lights and a 10amp protection device for the socket inside the shed. The protection devices would depend on what is protecting the original supply. If that 10amp device is on the rcd that prtoects several MCB's then I would move it to the non protective side and fit a 10/16/20 amp RCBO as the cable is buried. If the cable is SWA and it is 3 core with a dedicated CPC then you need only fit an MCB, even if it's buried.

So the shed protection devices would be RCBO at main CU...........MCBs, if it MCB at the main RCU then RCBOs in the shed. IMO if it was posibble I would MCB at main board and RCBOs in shed as that would give you a better installation regarding nuiscience tripping.

As this is in the garden and therefore a special location you would need to either notify this work or get an electrcian in that is part of a self certification scheme. Aslo all this work would need to be tested and certificated and again I would suggest getting someone in to do it if your not a qualified electrcian.