1-phase or 3-phase to house?

EML200 · May 1, 2021

Just been down to the basement to check what I've got. The supply to the (old) house comes from an 18mm cable, is split out to a live and neutral, goes to a 100A fuse and single-phase meter, and on to the consumer unit.

So, it's obvious that I've got single phase. But here's the problem: a second 18mm cable comes in with the first. It goes to a junction box (I haven't looked inside), and on to the consumer unit. Any idea what this second cable is? If it's phases 2/3, why does it go to the consumer unit?

And can I get free electricity from it? Just kidding... ?

loz2754 · May 1, 2021

A photo would be most helpful if at all possible please.

EML200 · May 1, 2021

Attached. Two cables entering at the far end corner (above and below the earth wire that goes off to the left). The top one goes to the fuse, the bottom one to the junction box. The CU is off on the right.

I've just done the obvious thing that I forgot to do - checked the lower cable with a Megger. It's live between the exit from the junction box and the CU. The Megger doesn't show either of the entry cables as being live, so presumably they're shielded.

Having said that, the Megger doesn't seem to be great - it's showing a small section of the neutral cable (just where the white tape goes around the cable) as being live as well, but it does show the entire connection from the junction box to the CU as live.

[ElectriciansForums.net] 1-phase or 3-phase to house?

westward10 · May 1, 2021

I would say that is an outgoing supply to another building maybe. Does the T&E from the top of the joint box go to the consumer unit.

snowhead · May 1, 2021

The second supply coming in isnt coming in, it's more likel a metered feed going out.

Beaten by Westward10.

EML200 · May 1, 2021

Interesting (and yes, the T&E goes to the consumer unit).

This is semi-rural and the two neighbours are maybe 100 - 200m away. The house closest to this cable was built in the 1940s, and was pretty much rebuilt a couple of years when some houses were built in their garden. So it's unlikely that anyone is (still?) using this supply.

If it is being used, then I'm paying for it, so I guess I should contact the supplier?

westward10 · May 1, 2021

Supplier won't be interested it is on your side. It looks pretty old judging by the corrosion to the saddles, if you know which circuit it is turn it off and see if you lose power anywhere and it is not impossible it supplies another house but not likely.

EML200 · May 1, 2021

Ok, I think you're right - it seems to be supplying an old garage around the back which also has a consumer unit.
Thanks westward10/snowhead.

telectrix · May 1, 2021

EML200 said:
Ok, I think you're right - it seems to be supplying an old garage around the back which also has a consumer unit.
Thanks westward10/snowhead.

seems logical.T/E from CU jointed int SWA to feed outbuilding. CU