I'm planning to build a shed in the far RH corner of the rear garden. It will have a reinforced concrete base, wood structure, flat roof and be just under the size that requires building regs approval.
It will take me some time to build the shed so it's not yet time to get a local electrician on side. I'm aware that this will be a new circuit or a sub-main (although I don't really understand what a sub-main is) and that this work will be subject to notification and Part P certification. I would want to do as much of the electrical install as I can.
I want to install the concrete slab and need to consider how to get the SWA cable into the shed:
The SWA cable will run along the fence at a height of approx 400mm.
I can see 3 possible routes to get the SWA cable from the fence to the shed - see drawing
a) Via an underground route (red in the drawing). The conduit will be 40mm waste pipe as that's what's in the come-in-handy box. I don't really want to buy a roll of twin wall convoluted stuff. What depth would I have to bury the conduit? The gap between shed and fence is only for maintenance purposes.
b) Via the mid air route (green in the drawing) through the shed wall. It would present a head height obstacle if the entry is at the near corner of the shed, less so at the far corner, which is the corner of the garden.
c) Via an overground route (blue in the drawing). I can make a cover to protect the cable out of 3mm steel or other suitable material.
The drawing is not to scale and there is another fence running L to R, 0.4m behind the shed, but not shown.
Are any of those routes suitable? Is 40mm waste pipe ok for the conduit?
The house has TN-C-S earth arrangement. Does this allow the shed earth to be connected to the house arrangement via the SWA armour? Or will I need to use 3 core SWA rather than 2 core?
My unqualified thoughts on the supply are:
1. Supply from a new MCB in house CU, where all the circuits are fed via the RCD.
2. 10mm T&E from CU to inside house rear wall; JB to change to 6mm SWA , sleeved where it passes through the house wall.
3. SWA will be clipped to the fence and go approx 15m to either far or near corner of the shed. SWA approx 0.4m above ground level so easily visible.
4. The shed to have a small CU with RCD, with 6A and 32A MCBs for LED lighting and a power ring main including four inside and one outside double sockets.
Lights: max 4 x 5ft LED batten lights; total 18W
Power load: Fixed pedestal drill (350W) and bench grinder (500W) plus portable tools and max 2 x 2kW fan heaters
Comments on that welcome.
It will take me some time to build the shed so it's not yet time to get a local electrician on side. I'm aware that this will be a new circuit or a sub-main (although I don't really understand what a sub-main is) and that this work will be subject to notification and Part P certification. I would want to do as much of the electrical install as I can.
I want to install the concrete slab and need to consider how to get the SWA cable into the shed:
The SWA cable will run along the fence at a height of approx 400mm.
I can see 3 possible routes to get the SWA cable from the fence to the shed - see drawing
a) Via an underground route (red in the drawing). The conduit will be 40mm waste pipe as that's what's in the come-in-handy box. I don't really want to buy a roll of twin wall convoluted stuff. What depth would I have to bury the conduit? The gap between shed and fence is only for maintenance purposes.
b) Via the mid air route (green in the drawing) through the shed wall. It would present a head height obstacle if the entry is at the near corner of the shed, less so at the far corner, which is the corner of the garden.
c) Via an overground route (blue in the drawing). I can make a cover to protect the cable out of 3mm steel or other suitable material.
The drawing is not to scale and there is another fence running L to R, 0.4m behind the shed, but not shown.
Are any of those routes suitable? Is 40mm waste pipe ok for the conduit?
The house has TN-C-S earth arrangement. Does this allow the shed earth to be connected to the house arrangement via the SWA armour? Or will I need to use 3 core SWA rather than 2 core?
My unqualified thoughts on the supply are:
1. Supply from a new MCB in house CU, where all the circuits are fed via the RCD.
2. 10mm T&E from CU to inside house rear wall; JB to change to 6mm SWA , sleeved where it passes through the house wall.
3. SWA will be clipped to the fence and go approx 15m to either far or near corner of the shed. SWA approx 0.4m above ground level so easily visible.
4. The shed to have a small CU with RCD, with 6A and 32A MCBs for LED lighting and a power ring main including four inside and one outside double sockets.
Lights: max 4 x 5ft LED batten lights; total 18W
Power load: Fixed pedestal drill (350W) and bench grinder (500W) plus portable tools and max 2 x 2kW fan heaters
Comments on that welcome.
