There are three basic types of electrical light switches. The first kind is a single light switch. The second kind is a 3 way switch that controls one light or fixture from two locations only. The third type is a 4 way switch that controls one light or fixture from three or more locations.

The quickest wiring method for 3-way switches is to place the light or fixture in the middle of the two switches. Youll need to look at the wiring diagram closely to understand how it is done. The electrical cable should be 12-2 electrical wire up to the first switch, then use 12-3 electrical wire to the light and then to the second switch.

The 12-3 Romex cable has an extra wire called a traveler wire (usually red), which is commonly used for 3 way switches. At the first switch, the 12-2 electrical wire from the circuit run enters through the bottom of the switch box and the hot (black) wire connects to the bottom right terminal on the switch.

The 12-3 electrical cable enters through the top of the switch box. The hot traveler (red) wire connects to top left terminal on the light switch. The black (hot) wire connects to the top right terminal on the light switch.

The 12-3 neutral (white) Romex wire connects directly to the 12-2 neutral Romex wire with wire nuts and the copper ground Romex wires are connected together with wire nuts in the same fashion. At the light fixture box, you should have two ends of 12-3 electrical cable hanging out. One end comes from the first light switch the other comes from the second light switch.

Next, twist the copper ground wires together with a wire nut to get them secured together and out of the way, and then twist the two red traveler wires together with a wire nut also.

Now, find the black wire that comes from the first switch box and the white wire that comes in from the second box and connect them together with wire nuts. Now, heres a really important step. You will need to mark each end of the white wire by wrapping it with black electrical tape. This means the wire is designated as a hot wire. This is a code requirement for using white wires for hot lines! It is a common practice for 3 and 4-way light switches.

Now, at the second switch, you will need to connect the red traveler wire to the top left terminal. The white, wire now marked as black with tape, connects to the upper right terminal. The black wire will connect to the lower right terminal screw. The copper ground wire will connect to the box if it’s a metal box or the green ground screw on the switch if the box is plastic.

The light box should now have a single black wire and a single white wire sticking out which is what you will need to connect the light to.