Could someone explain to me how to use a multimeter to check if a wire is live? It is for a house, so I am assuming its 120volts. I'm installing a ceiling fan and the wiring in the room is kind of weird. I don't want to just assume its off because I flipped the breaker in that room. (P.S. I don't want to flip the main breaker because I have some vital electrical devices running in the house). How to upholster a sofa?