A 1" pipe sounds like the entrance into the home. I suppose I would look to see where the ground clamp was (within 5' of the entrance point past that place in thew wall) and check the neutral connections.
If this is really a single conductor taking a significant amount of unbalanced neutral current to the street you would get a big field around it. Normally the pair of wires in a cable or raceway will cancel most of the field.
One conductor becomes an effective antenna.
