Advice For Garage Electrics

[pippo]

Hi all,

I am currently in the process of replacing an old timber garage which was there when we moved in. The old garage had electrics in as follows:

Mains - 20a mcb/rcd from house consumer unit, radial 2.5 twin and earth, this connects to armoured cable in a junction box under the downstairs bathroom then goes outside underground around 4m to the front of the garage.

Lights - 6a mcb same as the mains with 1.5 twin and earth, then armoured etc.

When the armoured cables entered the old garage it went to a junction box without any mcbs or anything then onto a single double socket for the mains and single light for the lights in standard cables.

I plan on restoring an old mini in the new garage and I would like to have quite a few lights (kitchen strobe jobbies) for good visability all switched individually so i can use only what i need at the time and around 6 double power outlets for ease although i doubt I will use them all at once. I will however be using some power tools like a mig welder and grinder etc and will also have an old pc out there for research purposes . Also I would like to put in an electric panel heater of some kind for the cold evenings. Garage will be 6mx3m internal and i will need a heater capable of heating that. So I have a couple of questions:

1) Should there be rcd/mcb's inside the garage as well as on the consumer unit?

2) Can electric panel heaters be run off the mains circuit or do i need a seperate circuit for this? if so would it be radial or ring and which mcb/cabling size?

3) Would it be better to put in a second cable and make the radial mains circuit a ring circuit with a 32a?


Thanks for any help

Pippo

 

[ban-all-sheds]

1) Split the tails in the house using henley block(s) - take one set to the existing CU, and the other to a 50A switchfuse.

2) Replace the cables running to the garage with 10mm² 3-core SWA from the switchfuse.

3) In the garage install a CU with RCBO(s) for the socket circuit(s) and MCB(s) for the lights.

If you don't have an isolator, (1) will require you to pull the service fuse, not really a recommended DIY task.

(2) Will require the cable to be buried at the right depth, and glanded properly.

(2) & (3) will require tests to be carried out on the circuit before energising which will need several £'00 of test equipment and the knowledge of how to use it.


Or get an electrician.

 

[pippo]

Hi ban-all-sheds,

Thanks for your advice. Im not keen on doing that myself so I will get a pro in. If I was to run the circuits in the garage, run the 10mm2 3-core SWA, mount the cu in the garage and leave all the tails labeled with plenty of length at each end would an electrician be happy to connect it up and test it as you suggested? If so would he/she require 2x 10mm2 3-core cables?

Thanks

Pippo

 

[ban-all-sheds]

You aren't in Part-P land up there, but I guess you'll still want an electrical certificate, so you need to discuss with your electrician what he/she is happy for you to do.

One 10mm² cable will be ample, and provide headroom for any reasonable future increases. You could install smaller but I don't see the point as the cost different is minimal and you only want to dig that trench once....

 

[bongos]

Im not keen on doing that myself so I will get a pro in. If I was to run the circuits in the garage, run the 10mm2 3-core SWA, mount the cu in the garage and leave all the tails labeled with plenty of length at each end would an electrician be happy to connect it up and test it as you suggested? If so would he/she require 2x 10mm2 3-core cables?

Many electricians will let you do the digging and laying of cables to save your money and their time but contact the electrician before you start the work so you can make sure that they are happy with this and that it takes a route that they are happy with as it will be them signing it off. You want to avoid having to dig two trenches if one is in the wrong place.

You would need only 1 x 10mm² swa for this installation from what you describe.

Find a local electrician here

 

[pippo]

perfect thanks