Cable ID running from electricity pole

jw2

There is a small National Grid box (transformer?) on the row of electricity lines next to our hedge and lawn. The ground screw company replacing an existing outbuilding for us have noticed black armoured cables running down each pole of this box and are concerned they come into our garden. The poles/box is actually in the hedge in the farmers field next to our garden but some of its supports for the poles are on our lawn. 

Obviously we would like to ensure the cables don’t run anywhere under our lawn where the foundations of the new outbuilding will be drilled. It’s a mystery as our house supply comes in elsewhere and there’s nothing else around except farmland. (The farmer had no idea they were there). I wondered if they were just earths of some kind and standard for this setup....can anyone shed any light? Thanks

Robin9

Perhaps of more importance ae the trees and undergrowth.

 What part of the country are you in ? Perhaps there is an engineer from the DNO who follow the issue up?


Ring the phone number on the plate  and get an address/email to whom you can send the photos.

Not clear on your photos but these cable seem to associated with the transformer earthing - in which case I would expect these to run into the field.

Have you a photo of the top -  are their some wires probably 4 in vertical format. ?

jw2

I'm in Cornwall. I should have said that I did try the National Grid 'check before you dig' page but no answer as yet. National Grid engineers were there a couple of months ago but of course i didn't know to ask the cable question at that point. I'll try and get a better photo of the top.

QrizB

Where does your electricity supply enter your house? Is the incoming supply cable overhead, or does it emerge from underground?

If there's no obvious other place for a supply to your house, and no other buildings nearby, I'd be inclined to say that transformer is there to supply you.

Your contractor should carry out a proper utility survey before digging. If you ask them and they look puzzled, they're probably cowboys.

Qyburn

That looks like an 11kV transformer, similar to the one serving our house. Ours has three cables going underground. The service cable supplying the house, looks a bit like SWA but is actually "Split Concentric". The low voltage earth connected to the 240V neutral, insulated as it comes down the pole. Finally the HV earth runs the other side of the pole and I'm told it would be routed diametrically opposite to the LV earth.

Grizzlebeard

As you seem to live in a very rural area it's most likely the downfeed is powering the nearest street power pole, from where it's distributed to the rest of or part of the village/local community. Check near by Street poles to see if any of them also have armoured cables running up them.

If so still DO NOT ASSUME a direct as-the-crow-flys straight route for any underground cabling, but at least that's a clue as to what's up.

I live in a small village (SE England) and a pole TX that supplies me has 5 or 6 downfeeds which go to local small businesses, a farm, and a handful of houses. The other 300~600 houses, including my next door neighbours, are on different circuits.The transformer may be only for street lights, but this is unlikely.

FreeBear

QrizB said: Your contractor should carry out a proper utility survey before digging. If you ask them and they look puzzled, they're probably cowboys.

A responsible contractor should have a "magic wand" for detecting underground cables.

Qyburn

FreeBear said:

QrizB said: Your contractor should carry out a proper utility survey before digging. If you ask them and they look puzzled, they're probably cowboys.

A responsible contractor should have a "magic wand" for detecting underground cables.

CAT (Cable Avoidance Tool) or "CAT and Genny", where you clip the signal generator (genny) onto the cable of interest and the CAT detects that specific frequency, so you know you're tracing that actual cable or something connected to it.

Round here the DNO will come out and trace and mark cables for you, if their mapping wasn't sufficiently accurate.

jw2

Have attached a pic of top of poles - crap quality sorry. 

Robin - the cables come in as two horizontal, run down to box, then leave again as three in vertical format??

This three vertical format cabling runs to a road and other houses.

QrizB - elec comes in to house from a pole in the lane, runs down the pole, under a road, then into house. We know this for sure as lines were upgraded a couple of years ago.

Qyburn - the two down cables are diammetrically opposite so sounds like your description but it is definitely not the supply to our house...

Thanks Grizzlebeard!

Thank you all for the great info. Clearly there's no simple answer and the downcables could well be a supply for somewhere...
Will be ringing National Grid tomorrow to chase my email - maybe their helpline will actually 'help'... My cynicism for getting an answer out of them led me to this forum..

Robin9

That's a single phase transformer  - probably 50kVA -  very common in rural areas. The 3 vertical wires are running at 240v.   I'm pretty certain that there are no cables in your property. Not particulalry clear but I think one of the cables down the pole is a U shaped wood to protect the cable -  the other may be plastic.

Best of luck in contacting NG.

jw2

Thanks Robin9. Both cables running down the poles are in U-shaped wooden covers.