The utility should determine if the load is balanced. The power supplier can check by disconnecting the jumper on the transformer. An example of this problem is ungrounded submersible water pumps. The voltmeter should not read DC voltage on the AC scale. Test voltmeters by connecting the two voltmeter leads to each terminal of a conventional 1.5-6 volt DC dry cell battery.
Digital voltmeters are well adapted to the analysis of stray voltage.
Establish an isolated ground rod at least 25' from the milking facility and also away from any underground pipes, electrical equipment, ground rods, or fencing. The rod should be driven at least 2' deep into moistened soil. Turn off electric fences. No load is operating in the parlor or barn at this time, but the primary neutral has not been disconnected. Open the main disconnect to the farm.