Famous 2 Black Wires On A Light Switch References. The black screw is usually common, and it seems to be coming from the red wire nut, which is the power source (am i seeing that correctly?) The green wire is the ground.

Attach the black wire from switch two to a contact on the light fixture. What type of switch do i need to buy to replace this one? Web there are 2 black wires running into the bottom and one red one at the top.