A metal detector is often used for much more than just finding treasure. The advanced circuitry in these machines is custom-tailored to find specific types of metallic items. When locating underground wires, the signal from the metal detector easily penetrates plastic conduit and detects the metallic wire inside. If the conduit is metal, this makes the process even easier.
Locate the structure that houses the wires, where they exit the ground. This gives you a rough estimate of the wire's location in the ground.
Turn the detector on and set the discrimination settings as low as possible. Adjust the sensitivity of the detector as high as possible while still maintaining stability. If the wires are carrying a lot of current, the sensitivity should be lowered until the machine stabilises.
Swing the detector loop back and forth over the area until the signal indicates a metal target. Ignore small, choppy signals. The signal should be strong and repeatable. Walk forward while swinging the coil, and soon you will find the path that the wires are taking. This path is indicated by a continuous target indication along the ground.
Spray a small dot on the ground in the area where you believe the wire originates from in the ground. When you have travelled a few feet with a continuous signal stop and mark the ground again, with a small spot of paint. Repeat this step until you have reached the end of the wire. Go back and connect the spray dots with the spray paint, so that you have a continuous paint-line on the ground. If you lose the signal, go back to the last paint dot and start again from there.
Practice with your metal detector often. This helps you determine what the different signals indicate.
Never dig up a live wire. Electrocution could result.