I had my neighbors wife tell me she had been shocked several times when touching her cooktop and sink when the water was running. Home built in the mid 1940's original GE pink appliances and still going. I went and discovered with the cooktop off and measuring the voltage to the metal drain pipe (after the plastic trap etc., not original) 3.4 volts. With the top on 74 volts.
Additional information: No main on the house two-wire typical wiring without ground, FPE panel. The water lines connecting the sink were also replace with plastic tubing.
Checking things out I found:
Several grounding style receptacles that had replaced original non-grounded receptalces with grounding conductors added but just loosely wrapped around metal water pipes. I added pipe clamps.
They added a new bathroom and the plumber changed the piping at the water heater to plastic tubing, thus breaking any bond between the hot and cold water. These are now bonded together, noting that the above receptacles wires had randomly selected either hot or cold piping.
I got into the panel and found all copper wiring, I was surprised and pleased. But I needed to go through and retorque everything. The worst was one of the service line conductors was so loose as a light pull would have removed it from the lugs. The family is living right though as there was no heat damage to the conductor. I exercised all the breakers and left the panel feeling that the FPE panel was in good condition.
Pulling the cooktop I found no option for pulling in an equipment grounding conductor as no bonding point was provided and the nuetral bonding point must of been located somewhere deep in the appliance or possible in the separate control unit which I did not desire to try to remove it from the wall (read as: I was not smart enough to figure out how). Well, giving up (and still with the problem) I start to put things back together. I pull out the noalox (conductive antioxident for AL conductors but works for CU) and individually coat the multiple (about 12) prongs in the connector in the hopes that a poor nuetral connection may possibly be improved. Finished up thinking I would need to tell them that they needed a new cooktop and found to my joy 3.4 V on the cooktop on or off.
It feels nice to save someone money, home, and possibly lives. Now to see how long this fix will last. They are starting a savings program for replacement.
Shane
