Run Electric Supply to new build garage from 16 amp new build house CU

DIY Sparky · Nov 14, 2018

I am planning to run a power to the garage from a 16 amps RDC from house CU in a new build. I want a power a twin socket, an internal light, and a floodlight. There is a power feed to a junction box on the outside of the house from a CU. My plan is to install a power supply as per the attached sketch. I will call an electrician to connect and test the system. Planning not to have CU in the garage as i will not need any more supply and want to keep the cost down. Any advice will be useful and how much an electrician would charge to connect and test?

[ElectriciansForums.net] Run Electric Supply to new build garage from 16 amp new build house CU

Octopus · Nov 14, 2018

No idea .... I never test and inspect other peoples work.

Best you find a spark willing to do this before you do anything AND this falls under part p of the building regs too

DIY Sparky · Nov 14, 2018

Thanks, Murdoch, i fully understand where you are coming from re the building regs that is why I want the electrician to connect all wires and test. I want to do all the labour work to reduce cost. Just wanted to know if my thinking on the scetch is right. I will not do anything without checked and tested by an electrician as it is my son's new house.

Octopus · Nov 14, 2018

DIY Sparky said:
Thanks, Murdoch, i fully understand where you are coming from re the building regs that is why I want the electrician to connect all wires and test. I want to do all the labour work to reduce cost. Just wanted to know if my thinking on the scetch is right. I will not do anything without checked and tested by an electrician as it is my son's new house.

As I previously stated, find a spark to work with and ask them ....

Toneyz · Nov 14, 2018

You need an electrician that belongs to a third party scheme. How much they charge I don't know maybe another member could answer that. I think that they would check the design and inspect at intervals.

Toneyz · Nov 14, 2018

If it was me I would install 3 core SWA cable to the garage earthing the SWA with an earthnut (to earth the SWA) and install a small consumer unit (2 way). I assume that as noted it is a new house and the supply to the outside box complies with the 17th edition of BS7671. If a photo of existing C.U. and outside box was posted I could comment further.

MJPD29 · Nov 15, 2018

I like the drawing you have done your research well

Michael Davis-McCoy · Nov 15, 2018

Hi Anthony,
Why would you use a 3 core swa instead of a 2 core swa. The 2 core's are the right colours and for single phase. You would have to sleeve the 3 core.

BruvDunk · Nov 15, 2018

Always better to future proof any additions. i.e. workshop.
So a small garage CU would be the way i'd recommend.

What type of cable would depend on route etc, but SWA is always a favourite..
A decent Electrician will explain all this when he prices it up.

DPG · Nov 15, 2018

I would also use metal clad sockets and pvc trunking and bushes.

Toneyz · Nov 15, 2018

Michael Davis-McCoy said:
Hi Anthony,
Why would you use a 3 core swa instead of a 2 core swa. The 2 core's are the right colours and for single phase. You would have to sleeve the 3 core.

You can get three core SWA in brown, blue and green/yellow if not sleave or tape it. As for the 3rd core as CPC always have done, reliable and don't have to worry too much about corrosion.

Deleted member 105166 · Nov 15, 2018

Dig the trench and run the pipe/ducting with a draw string. The electrician will appreciate you doing this aspect. Then let him specify and pull the cable through, as otherwise he cannot inspect it.

DIY Sparky · Nov 17, 2018

Murdoch said:
As I previously stated, find a spark to work with and ask them ....

Thanks, Murdoch, I am working on this at the moment.

DIY Sparky · Nov 17, 2018

TonyMitchell said:
Dig the trench and run the pipe/ducting with a draw string. The electrician will appreciate you doing this aspect. Then let him specify and pull the cable through, as otherwise he cannot inspect it.

Thanks, the outside connection box from house 16 amp CU, underground pipe and ducting has already been installed as per the sketch during the new build. The distance between the house and the garage wall is 4 meters.

DIY Sparky · Nov 17, 2018

PaulDuncan said:
Always better to future proof any additions. i.e. workshop.
So a small garage CU would be the way i'd recommend.

What type of cable would depend on route etc, but SWA is always a favourite..
A decent Electrician will explain all this when he prices it up.

Thanks, Paul, my son is not a DIYer at all, he will only power a lawn mover plus just need a power to an internal light and floodlight. I might occasionally use the 13 amp socket for hand tools.