Get into the habit of checking a unit’s frame to a trusted ground before you start working on anything with a power related issue.
I went out on this call expecting something to be wrong with the refrigerator and so as usual I start the standard diagnostic process. It was plugged into a standard outlet and not a gfi so I automatically rule out nuisance trips from being the culprit. I opened the door, felt the hot gas lines, listened to the fans, checked the temps in the freezer and the refrigerator, cycled the icemaker, put the unit into defrost and heard the heaters kick on and start sizzling. Everything seemed to be normal and working as expected.
At this point I figured a mouse may have gotten into a wire or the icemaker line and I really needed to check the back compartment out anyway so I pulled it out to take a look. Again everything looked normal, nothing unusual. I unplugged the unit, checked for continuity between neutral and l1, ground and l1 and again nothing unusual. I plugged the refrigerator back into the outlet and needed to roll it forward a little so I pushed the bare metal back with my hand forward and in doing so my knee hit the copper line coming out of the wall. This is where I simultaneously found the problem and I took 120 volts straight through the chest, violent shaking the whole bit. It hurt like hell and left me scared to touch the damn thing again, but I went back to work.
I checked the outlet and it was wired backwards (hot and neutral reversed) but that's not really that uncommon for a house that's 20+ years old around here. I checked ground to neutral and I got some really big fluctuations in resistance that were sometimes unreadable by my fluke meter so I knew something was going on but not sure exactly what. So I checked ground to the copper pipe. 120 volts. I plugged the refrigerator into a gfi outlet that had a microwave on it and turned off the breaker to the refrigerator and got her in contact with an electrician I know and trust. He went out and a few days later I spoke with the customer again and she told me that the electrician said I was really lucky so I had to call and speak with him about it. I called him and he told me that the ground wire had shorted out to the hot line, energizing everything. I asked him how that was possible without tripping the breaker and he said that the outlet didn't return to ground, that someone had crawled under the house and rigged up the electrical line at some point probably removing the ground and that something chewed the wires shorting the ground and the hot line. The lady said she had no knowledge of it and it must have been done before she bought the house.
I'm making the assumption that something had chewed the wire shorting the rigged up ungrounded ground wire to the hot line. I still don't understand completely what happened but I know I got the shit shocked out of me and if I would have had a hand hold on something I may have been killed, but I wasn't thankfully. It still scares me though. This woman was old and frail and if she would have touched the refrigerator and the sink or the microwave anything to a good ground it probably would have killed her. Be careful with electricity. I've been shocked many times but never like that. 120 volts are extremely powerful. We tend to get complacent with it.