I have an old switch box that has a single cable coming into it with a black wire and a white wire. I've confirmed with a voltage tester that the black wire is hot. Before installing an electronic remote switch, I want to make sure that the white wire is a neutral.
My doubt comes because my house has a number of switches that are set up as a switch loop, where a single cable comes into the box, and one of the conductors is always hot (usually fed by power coming into the fixture) and the other conductor is used as a switched hot. In this old switch box, I'm wondering whether the cable is an abandoned switch loop where the always hot conductor is still connected but the switched hot doesn't connect to a load.
Is there a way to test this? I believe that measuring hot to neutral on a multimeter should give 120V, correct? What would measuring hot to switched hot give? I'm just looking for a way to safely and definitively confirm that the non-hot wire is a neutral on the same circuit as the hot wire.