How to Run a New Wire From an Existing Switch to a New Light
- 1). Turn the power off to the circuit you wish to work on at the distribution panel. Confirm that the power is off by touching the tip of a non-contact voltage detector to the insulation on each wire attached to the switch. If the voltage detector illuminates or makes an audible noise, there is still power at the wires.
- 2). Strip 1/2 inch of insulation off the three wires in the 14/3-gauge cable.
- 3). Remove the twist-on wire connector that fastens the two white neutral wires in the switch's electrical box. Twist the white wire from the 14/3-gauge wire onto the two existing wires and reinstall the twist-on wire connector.
- 4). Cut the black wire that is fastened to the top terminal on the switch 3 to 4 inches from the switch. Strip 1/2 inch of insulation off both ends of this wire. Connect the 14/3-gauge black wire and the two existing back wires by twisting them together with pliers. Install a twist on wire connector on top of the connection.
- 5). Remove the twist on wire connector that fastens the two green wires in the switch's electrical box. Twist the green wire from the 14/3-gauge wire onto the two existing wires and reinstall the twist on wire connector.
- 6). Run the 14/3 wire to the new light and strip 1/2 inch off the end of the three wires.
- 7). Connect the black wire to the hot terminal for the light by backing off the terminal screw. Wrapping the black wire around the screw and tightening it back down. Connect the white wire to the neutral connect on the light in the same manner. Fasten the green wire to the grounding screw at the back of the light's electrical box.
Source...