Power to Outside Garage

[Paul]

The set up is that my garage is about 5m from the house, and has no power. The house fuse box is (fortunately) located inside the house on the wall facing the garage, and has a spare 16A RCD protected MCB. My plan would be to take a cable through the house wall close to the fusebox, down the house wall, under some existing concrete, and then up and through the wall of the garage where it connects to a small fuse box. I want to make sure this is legal and safe. I would intend to use 2.5mm2 normal PVC cable in a plastic conduit down to the ground, where a junction box joins it with armoured cable for the underground section. Where the armoured cable surfaces at the garage, there would again be PVC cable in a plastic conduit. (The only reason I'm not using armoured cable for the whole run is that I'm assuming it doesn't like making 90 degree bends too much.)

So:

Does this sound like a good plan, please? How deep does the cable need to be buried, and what other precuations must be taken? Is there any alternatie to armoured cable underground (I'd prefer to use one single length of cable if I could)? Is this a DIY job (with respect to joining armoured and PVC cable)?!?!?!

Thanks very much,

Regards,

Paul.

[Owain]

"Paul" wrote | The set up is that my garage is about 5m from the house, and | has no power. The house fuse box is (fortunately) located | inside the house on the wall facing the garage, and has a | spare 16A RCD protected MCB. My plan would be to take a cable | through the house wall close to the fusebox, down the house | wall, under some existing concrete, and then up and through | the wall of the garage where it connects to a small fuse box. | I want to make sure this is legal and safe. I would intend | to use 2.5mm2 normal PVC cable in a plastic conduit down to the | ground, where a junction box joins it with armoured cable for the | underground section. Where the armoured cable surfaces at the | garage, there would again be PVC cable in a plastic conduit. | (The only reason I'm not using armoured cable for the whole | run is that I'm assuming it doesn't like making 90 degree bends | too much.)

It will make 90degree bends happily enough but with a fairly large minimum bending radius. But for a 5m length on a 16A MCB you won't be using ginormous cable anyway.

I think it would be much more preferable to (a) do the whole run in one piece (b) if jointing to PVC, get the joints indoors. If you have suspended floors below the house CU you could probably drop down vertically inside the building and turn horizontal in the floor void.

| Does this sound like a good plan, please? | How deep does the cable need to be buried, and what other precuations | must be taken?

Deep enough to protect it from harm. Under concrete > 1 spade depth should be adequate; ensure that anyone breaking the concrete isn't going to damage the cable. Above the cable, a few inches below the surface (or the concrete) put "cable buried below" marking tape.

| Is there any alternatie to armoured cable underground (I'd prefer | to use one single length of cable if I could)?

You could use Hi-Tuff cable suspended from a catenary, but an ordinary garage might not give enough height for sufficient clearance (especially if there is a driveway or vehicular access to be crossed), and it will be more visually intrusive.

| Is this a DIY job (with respect to joining armoured and PVC | cable)?!?!?!

No reason why not, get a couple of metres extra SWA and spare glands, and practice first, measuring where the gland ends up compared to where you started from.

Owain

[callmepaul]

That's very helpful - thanks very much Owain.

Regards,

Paul