Dimmer Switch Wiring Diagram Red Wire. You will find a red and black wire connected to the switch. Bulbs that include a power supply like led and cfl bulbs may emit a soft glow even when the switch is turned off.
If insulating label is not affixed to Red lead use a small wire nut or electrical tape to cap off. A 3 wire nm connects the travelers of the dimmer to the travelers of the 3 way switch. The black and red wires between SW1 and SW2 are connected to the traveler terminals.
Remove 34 inch of casing from the end of the house wires and the dimmer switch wires if needed.
The green ground lead on the switch attaches to the circuit grounding wire which is usually a bare copper or green insulated wire. When installing your dimmer remember electricity flows into it on one side and out on the other side. A two way switchuk Schematic diagram of old wire colours. A black wire lead on the dimmer attaches to one of the two black circuit wires in the box A second black sometimes red wire on the dimmer attaches to the other black circuit wire in the box.