Why do I have two black wires on my light switch?
Considering this, why does light switch have 2 black wires?
The bare or green-wrapped ground wires serve as a backup to divert the power safely away in case of an electrical fault. In most cases, two black wires will be attached to the switch's two terminal screws.
Beside above, why do I have 3 black wires on my light switch? If the light turns on, the second black wire you connected to the switch is the switch feed and the unconnected black wire is the feed to the other loads. If the light doesn't turn on, then it's the other way around: the connected wire feeds the other loads and the disconnected wire is the light feed.
Besides, how do you wire a switch with two black wires?
If the switch box wiring has a bare ground wire, connect it to the green terminal screw on the switch. Connect the two hot (black) wires to the two brass terminals on the new switch. Gently push the new switch back into the box. Fasten the switch to the box with the two long screws at the top and bottom of the switch.
Does it matter which wire goes where on a light switch?
If your switch has a “LINE” marking, the always hot wire goes to this. The other connection will be “LOAD” where the load (ie light fixture) is wired. The load wire may have red electrical tape on it to differentiate.