When you need to control a light from two different locations, a 2-way switch is the answer. It is also known as a single pole double throw (SPDT) switch and can be found in almost all electrical applications, from electric guitars to car engines.
Steps to Wire a Two-Way Switch
A two-way switch connects one circuit to another by rerouting its signals. It typically uses a common terminal that carries the power to either switch, a selector that changes the signal path, and a circuit to which the switches can connect.
There are three screw terminals on a two-way switch: COM, L1 and L2. These terminals can be connected in one of several ways.
For example, if both switches are toggled on at the same time, both COM terminals will be connected to the L1 terminals, creating a complete circuit. This allows current to flow from the switch to the bulb.
Alternatively, if both switches are toggled off at the same time, neither COM terminal will be connected to the L1 terminals, and there will be no way for current to flow.
To wire a two-way switch, you need the correct type of wiring and the right switches to match your circuit. This is especially important if you want to control multiple appliances from different switches or use a two-way switch for a decorative light fixture.
Start by turning off power at your service panel. This is often done with a breaker switch located in the wall. Look for a label next to the breaker that describes the switch and its location.
Feed a length of 14/2 or 14/3 NM Cable between the two switch boxes. This type of cable contains two conductor wires, one black and one white, plus a third bare copper wire that’s referred to as a ground wire. This wire is essential to running the power from the first switch box to the second, since it’s what carries the electricity from the power source to the switches.
The black wire is a hot wire, but it’s also a traveler wire that transports power from one switch box to the other. This means that the power runs from the black wire to the red wire when the first switch turns the light on, and from the red wire to the black wire when the second switch turns it off.
Once both the red and black wires are connected to the switch screws, run a length of 14/2 or 14/3 cable from each switch box to the other. The length of wire should be long enough to reach the switch boxes, and it should end at one of the green screw terminals in each box.
If you are installing the switches yourself, it’s also a good idea to label the white and red wires in each box so you can find them later. This will help prevent mistakes when the wires are reconnected later on.
A two-way switch is usually used to switch a light from both sides of a room, but it can be used for other applications, such as switching the lights in a hallway from the main entrance to the hall. You can also use a two-way switch to control an appliance from both sides of the house, such as a fridge or an oven.