Underground pipe identification

[Bodgit]

I posted on Wednesday about capping an underground pipe (here:

When I saw the leaky pipe close to the house, I was sure it was iron (around 1" dia, now buried again). I've just dug the pipe up in the woods and that one is copper (around 1 3/4" dia, buried about 2ft deep). So I'm now not sure it's the same pipe, or even if it's connected!

When the surveyors were searching for the pipes, they connected used a cat & genny. They connected a valve near the old swimming pool to the genny and traced the pipe up into the woods. I guess, where the ground is wet, it would have been possible for the signal to transfer onto another pipe. Is this common, or even possible?

What concerns me is that there is an underground electricity feed running through the woods and I certainly don't want to cut that! The electricity cable would be 415v, feeding 3 houses. I've looked at the place where the cable comes from underground and feeds the 3 electricity meters, and this is around 1" dia and covered in denso tape. I can't easily determine the material without removing the tape. The earth cables are all connected to the cable covering near the main fuses.

So, were electricity cables ever run through copper pipes when underground? To determine if the pipe contains the electricity feed, can I just test for continuity, using a multimeter, between the house earths and the pipe in the woods? Any other suggestions?

[Andrew Mawson]

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ground

house

Very easy to get cross coupling when using a genny with a CAT. When I was tracing power cables on my place it was impossible to follow them past concrete slabs that had re-bar in them as every bit of steel responded.

AWEM

[Onetap]

Yeah but surely the mains cable would be traceable without the genny and it's route could be marked? The genny is only needed for conductive pipes that don't carry any electricity.

The electricity and water suppliers usually have drawings of their services, with copies available for a fee. I thought mains water was usually in lead, steel or plastic. I've never heard of copper being used.

[andrew]

Only if there is some noise on the conducter, the CAT is only a signal receiver and depends on some signal leaking from the wire. The first position listens for 50Hz, the second more generally higher frequencies that may be induced in the line and the third is tuned to the signal generator, this more specific frequency allows the CAT to give a fairly precise depth to the cable but I didn't figure how.

And they are often very wrong IME, even transco have problems as evidenced by their man sticking a fork prong through a 32mm medium pressure main when they connected our supply, it was the neighbour's supply and marked as crossing the road directly 20m away instead of running along the road verge on our side.

AJH

[Bodgit]

How would I do that? I can get to one end of the cable but I have no idea where the other end is!

Thanks - I might investigate that.

[Bodgit]

It's not mains water - it's a private supply from a reservoir to feed an old (defunct) swimming pool. I would have expected it to be iron as it was installed in the 1880s, but I suppose it could have been replaced later.

[Bodgit]

Do you have any idea when copper was first used?

[Bodgit]

I've cut it now! It was empty. It's a pretty thick pipe though - probably worth a bob or two if I could dig it up!

I need to search harder to try to find the correct pipe now!

Thanks for the replies.