this came from the breakers page:
If breaker assessment of net current does not identify net pair - suspect paralleled grounding conductor (neutral) returning to another panel or else a neutral/ground connection shunting current to another grounding path - see other magnetic fields measured (telephone, gas, cable or circuit combining any possible conductor(s)).
Note that GFCI's trip at 5 mA… even 0.5 A (500mA) of net current can create objectionable magnetic fields particularly within 3 feet of conductors, more common net currents are in the range of >0.5 to 10 amps or even higher.
Note that if amps on neutral are 12A and if water line amps is 2A then not much reason to suspect neutral connection issue with utility… however if neutral is 8A and water line is 4A then reasonable suspicion of utility neutral connection is justified.
Note voltage problems means one hot leg will show higher voltage than 120V and the other leg will show lower voltage. In this case the plumber may be at risk when he cuts through the pipe to insert a spacer (jumper cables advised).
Note dryers installed now must be supplied by a four-pronged cable which includes an equipment grounding conductor. Printed instructions on the dryer specify that the neutral-ground bond installed at the factory be disconnected when used with four-prong conductor cable. Instructions are sometimes poorly worded and installer may miss this requirement - double check (unplug dryer).
Note that if a magnetic field is less than 0.1mG (or same as ambient field due to power line(s) at distance of 2 feet from wire there is no reason to suspect a wiring error.