I was digging the holes for some crepe myrtle saplings and I sliced into a wire with one unlucky shovel stroke. They do not seem to be carrying any voltage, but I haven't hooked my multi-meter up to it yet. I've called 811 several times in the past, and nothing has ever been marked out anywhere near this side of the yard. The wires themselves are 2 red, 1 white, solid copper core, maybe 20 gauge (slightly heavier than say speaker wire). They are buried ~4 inches below the surface with no conduit or protection. They are a few inches away from the sprinkler PVC pipe, running roughly parallel to it and the driveway, towards the street away from the front corner of the garage where the sprinkler control system is.

The sprinkler control box still has power and it can still turn on the sprinklers. I did a short test run of the zone that the wires are running through, and they had normal pressure (after pushing out all the air that accumulated over the winter).

I switched to a hand-spade and started tracing the wire route through the garden. The wire seems to be getting deeper as it approaches the house, but I lost it in the twilight under a tree root.

Does anyone have a premonition about what these wires could be? If I do test the wire and find it dead, is there any danger in yanking the severed wire out of the ground to trace it? Is it worth calling 811 again and waiting to see if any of the utilities own up to it?

Additional Information (in response to comments):

The sprinkler system came with the house, so it's builder grade. I'm tempted to believe the theory that they are trace wires for the sprinkler PVC, except that I've gleefully hacked through the PVC on the other side of the yard with no sign of wires. I have not yet disassembled the box wiring to see if a white and two red wires connect to it, although the sprinkler panel and manual don't mention any fancy features like rain sensors.

We have no exterior electrics. No lights or fountains or anything. The only outdoor outlets we have are built into the base of the house. The nearest one to these wires is on the other side of the driveway.

I agree that it is unlikely it's any part of a utility. The location is haphazard and I'm pretty sure there's a building code for underground current carrying wires to have conduit. I can see the builders skimping on that, but not a utility.

  • 3
    I would open up the sprinkler box and look for 2 reds/white. maybe it's a moisture meter, rain sensor or something along those lines?
    – Steven
    Mar 28, 2014 at 2:07
  • 1
    Who installed the sprinkler system? Someone may have put some unconnected wires in the trench so the plastic pipes would show up on a metal detector. I know that that is done (by code?) for non-metallic gas lines...
    – DJohnM
    Mar 28, 2014 at 3:08
  • 5
    Underground dog fence?
    – Tester101
    Mar 28, 2014 at 14:02
  • 2
    Quite a while ago I used to work for the gas company and we'd tape a tracer wire to the pipe when installing. Sometimes someone would forget it and we would add it to the trench after the pipe was partially buried. However, that was only one wire as that is all that is needed for tracing. Mar 28, 2014 at 20:42
  • 1
    I've helped install a few invisible dog boundary fences and all 3 times they were just one 18/20 gauge wire, never more.
    – user20754
    Mar 31, 2014 at 18:50

1 Answer 1


The wires do indeed go to the sprinkler system. There turned out to be a 4th white wire I hadn't yet uncovered. The two sets provide the current to open control valves for the two zones on the other side of the driveway.

I finally got input from a professional sprinkler repair company. They were baffled at first, because the pipes appear to go all the way around the house. The sprinkler guys finally decided that those had to be stubbed extensions for adding a zone to the backyard. Additionally, the wires turn under the drive at a different point than the actual water supply pipe.

Finally, I didn't detect the problem because there was another long standing problem with the zone they supplied that prevented it from getting water pressure.

  • 1
    Glad you got it figured out and thanks for checking back and solving the "mystery" for all here:)
    – user20127
    Apr 16, 2015 at 22:00

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