Running a supply to a garage

[AndyNicol]

I want to run two circuits out to a garage.
I want to have a lighting circuit and a couple of sockets.
I've buried some 4 core armoured cable at about 750mm and marked it with caution tape just above. I plan to install a small consumer unit in the house with a 40A RCD, 6A MCB & 16A MCB.
My question is how should I connect a pigtail from the meter to this additional consumer unit and should I use the armour as earth and have 2 neutral lines or use one of the conductors as earth and have only one neutral line??

 

[breezer]

you should have posted this question in the electrics forum

 

[alexnic]

You would be better fitting the small CU in the garage, terminating the SWA in a junction box at the main board and connecting into a spare fuse/ccircuit breaker in the main CU (if possible)

 

[AndyNicol]

There is no space left on the current CU in the house.
Therefore I have to fit an RCD in the house anyway.
I also intend to have all of the external connections sealed to IP66.
This would not be easy with 2 standalone MCB's in the garage.
Also, if someone does manage to break into the armoured cable, isn't it better that the largest possible current is 16A rather than the 30A or 40A rating of the internal fuse.
The question I'm realy unsure of is the connection of the 4 armoured cores and if I need to use one of the conductors as earth or just the armour??

 

[Tec-wiz]

The outer swa of the cable is there to protect the user and cable. So the protective conductor should be one of the cores witin the main cable. Then if you have a poor contact on the gland the protection to the user is not circumvented. Hope this helps

 

[alexnic]

if you plan to fit a new RCD in the house anyway and your main CU is 'full' why not fit a new split-load consumer unit that incorporates the RCD and then you will have spare room for the garage supply.

Normal practice is to fit a garage consumer unit which incorportes the RCD and 2-MCB's (16a / 6A).

You will only need 3-cores of the SWA Live / Neutral / Earth as the mains feed into the garage CU. I would still earth the outer protective core of the SWA to the earth connection ('belt & braces')