I was replacing several old 2-pronged outlets with new 3-pronged outlets. I replaced one, flicked the breaker back on, and used the outlet checker (it illuminates some LEDs that indicate if your wiring is correct). Got it right. Did it again. Good again.
I start to get confident. I turn off a couple breakers and start work on three of them at once. When I get to number three, I start to have doubts about the first two, so I leave the third unwired (I capped each individual wire for safety) and flicked on the electricity to test outlets 1 and 2.
This is where it gets bizarre. I don’t remember what the outlet checker said, but it wasn’t good. So I checked the voltages with my multimeter and with the little neon light live wire checker. This is what I found, measured from the slots of both new outlets.
Voltage between hot and neutral: 0V
Voltage between hot and ground: 120V
Voltage between neutral and ground: 120V
Not good. I turn off the juice and inspect my wiring. Looks right. Also, I don’t think I could wire tbe hot to the ground as there wasn’t a ground wire – it was grounded through the conduit.
I can’t for the life of me figure out what could cause this. I turn the 'lectric back on, and test the first two I’d done (the ones that had tested good before), and those were now also showing the same bad voltages, along with outlets I hadn’t touched. At this point I’m wondering what this will do the electrical appliances and if I’ll start a fire, so I turn it off again.
The only thing I can think of is to connect the last outlet, which I do and try again. Everything is back to normal.
WTF?
The last details that may be important are that the last outlet had four wires – two wires that connect to the hot side and two that connect to the neutral. The two hot and two neutral terminals were bridged together on the old and the new outlet.
The only (possible) damage I found from the voltage switch was that the answering machine transformer did not work the next day and had to be replaced.
Any ideas?