One is the power coming into the box the other black is power going to the light. I think it means you dont have a neutral.
All About Light Switch Wiring Better Homes Amp Gardens
Light switch only one black wire. The green screw on the switch is it to ground the switch. Yep just transfer the wires across to the new switch connecting them to the same terminals as they are now. Rf lighting 21 nov 2010. 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. 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.
The black and the white are both hot. My read is that its a cheap way to wire a light switch with this type of cable. Heres a video to determine whether or not you have a neutral. 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. This type of switch lets you turn the light off or on from more than one place in the room. This is an updated version of the first arrangement.
These connect to the black and white wires in the electrical box with the provided larger wire nuts. The electrician should have put a piece of black tape on the white wire to indicate its hot. Your switch is opening and closing the circuit to allow power to your light. I would check that the load wire probably black is securely connected to the screw labeled load. You should actually be connecting two black wires to the switch. Smart switches use a neutral and a ground wire in addition to the line and load black wires.
A single pole single throw switch such as a light switch. Light fixtures with more than one lamp may have a pair of black and white wires for each lamp. The correct configuration should be black power in to switch black power to light to other side of switch. This type of switch has two brass screws usually on the bottom and a copper or black screw on the top left. Ideally the old switch is still there so you can wire the new one up the same way as the old one. Dont worry about having two reds and a black this is quite normal.
Gallery of Light Switch Only One Black Wire
