These connect to the black and white wires in the electrical box with the provided larger wire nuts. The red and black are used for hot and the white neutral wire at the switch box allows for powering a timer remote control or other programmable switch.

Need Help With Gfci Switch Combo Only Two Wir Leviton
Light switch only one black wire. This is an updated version of the first arrangement. The black and the white are both hot. So usually a standard single pole dumb switch has two blacks. The hot wire in a 120 volt residential ac circuit usually is coated with black insulation while the return or neutral wire is white. Heres a video to determine whether or not you have a neutral. Smart switches use a neutral and a ground wire in addition to the line and load black wires.
My read is that its a cheap way to wire a light switch with this type of cable. Your switch is opening and closing the circuit to allow power to your light. One is the power coming into the box the other black is power going to the light. The correct configuration should be black power in to switch black power to light to other side of switch. You should actually be connecting two black wires to the switch. Light fixtures with more than one lamp may have a pair of black and white wires for each lamp.
I think it means you dont have a neutral. The green screw on the switch is it to ground the switch. The electrician should have put a piece of black tape on the white wire to indicate its hot. I would check that the load wire probably black is securely connected to the screw labeled load. This type of switch has two brass screws usually on the bottom and a copper or black screw on the top left. A single pole single throw switch such as a light switch.
Ideally the old switch is still there so you can wire the new one up the same way as the old one. This type of switch lets you turn the light off or on from more than one place in the room. Rf lighting 21 nov 2010. Because the electrical code as of the 2011 nec update requires a neutral wire in most new switch boxes a 3 wire cable runs between the light and switch. Yep just transfer the wires across to the new switch connecting them to the same terminals as they are now. Dont worry about having two reds and a black this is quite normal.