I’m changing the switches around the house and some of the boxes are mixed light switch / GFCI outlet. After turning off the power, opening one of the boxes and pulling out the switches and outlet, I made sure no wires are touching and turned the power back on to be able to identify the line coming from the panel vs. all the other wires.
Originally, there was a bundle of white neutral wires all connected together and going off to various directions. Before turning on the power to find the line from the panel, I disconnected the neutral wire bundle, i.e. I now had three disconnected white wires going into the wall and one only connected to the GFCI outlet.
After turning on the power, I expected all white wires to have no voltage on them — as they are supposed to be neutral, right? But the situation turned out different. Two of the whites going into the wall now have voltage, as well as the white wire that’s only connected to the GFCI outlet and nothing else.
So my questions are:
- How come the white wire only connected to the GFCI outlet now has voltage on it? Is this due to the electronics in the GFCI outlet working as a load and passing voltage through?
- How come there is voltage on the white wires going into the wall? Could they be carrying return voltage from other GFCI outlets? Or would this be to some other load connected down the line and voltage coming back without a way to go back to the panel?