Just came from an interesting service call. It was a halfway house for veterans that I have worked at before. They have a number of duplex units built in the 50's, no equipment grounds at any receptacles.
Anyway a resident complained of shocks received off the refrig. When I got there they described the shocks as a snap accompianied by a blue spark. They get them whenever they touch anything metal and also the phone and the thermostat. Well I told them it was static electricity, but I would check the fridge anyway.
Well when the fridge is running, it will light my non contact tester when held close to the cabinet. So I got my analog meter and checked from a part of the fridge that was not painted to the grounded gas line nearby. I got about 13 volts. Remember this fridge has no equipment ground with the old 2 wire system.
So now I am thinking, in addition to the static shocks, they could've gotten a real current shock off the fridge. Is the 13 volts excessive? As soon as the fridge shuts off it goes away. I told them, short of running a new circuit, the only thing to do is get a new fridge. I know if I put in a GFCI it will not hold.
I know the code requires refrigerators to be grounded, but if they can't pay for a new circuit, what else is there to do?