Garden shed electrics

[b21playa]

Hi all

Just finished building a 30sqm shed from concrete blocks and now need some electrics in there

Now im not part p registered, so i will be notifying lbac and pay the fee for them to check afterwards, but i first need to draw up what needs to be done and need some help

currently have a crabtree split cu, which is about 40m away from the shed. the cu is at the front of the house, but i can get the cable into the garage and run it along the wall

was thinking of using 4mm or 6mm as rreally only need power for lights and maybe some power tools

is it best for me to run the swa directly from the cu or from a metal jb close to it going outside?

 

[shinysi]

Hi personally i would use the 6mm swa, 6mm will give you just over 40A at the shed and 4mm around 33A,i know you are only looking at some lights and a few sockets but the last thing you want is to find things change in the future and you need to replace the cable, you can still only put in a 16A socket circuit and 6A lighting circuit in a 40A two way C/U, but it gives you a bit of expansion room.
It just depends on whether you want to pay the extra for the 6mm cable.
As for connecting the swa into the consumer unit i personnally woudn't and would connect it in to an adaptable box (others may disagree) with glands and remembering to make sure you earth the armour, then just use the same size T/E cable to connect to the main C/U, as for the shed C/U you can do it the same or some small C/U's have room to connect in directly it depends on the make and style.
Hope that is of some help.

 

[ian.settle1]

Don't forget the volt drop on a 40 metre run neither.

 

[pmac10]

hi, did a totally unrelated job recently over a relatively long run and calculated full load current at @39. something, decided to consult the wiring regs table and im pretty sure 6mm cable was 39A at ambient temp. although this device(industrial water heater) would never run at full load, the fact that it COULD, made me chose 10mm(much to my annoyance!)
the regs also have a simple calculation for voltage drop also

 

[Sintra]

A 40M run of 6mm SWA with a load of 39A has a volt drop of 11.388v just below the 5% limit of 11.5v.

 

[patricklondon]

get in touch with your labc before you start as some boroughs insist on an inspection before electrical works are started

 

[mechelec]

A 40M run of 6mm SWA with a load of 39A has a volt drop of 11.388v just below the 5% limit of 11.5v.

3% for lighting circuits and there will be one in the shed so it looks like 10mm swa needed

 

[pennywise]

Thought that the 6mm is a power dis circuit so you would only have to allow the volt drop for the power ie 5% and then apply the lighting 3% to the lighting circuit within the shed only taking into account the length of the circuit form the shed DB or fused spur to the lights.

 

[mechelec]

Thought that the 6mm is a power dis circuit so you would only have to allow the volt drop for the power ie 5% and then apply the lighting 3% to the lighting circuit within the shed only taking into account the length of the circuit form the shed DB or fused spur to the lights.

The volt drop is from the origin of the supply so the distribution cable volt drop needs to be added to the volt drop of the lighting circuit.

 

[pennywise]

fare do's