Wiring a 2-Way Switch

    How to wire a 2 way switch. Wiring a 2-way switch is about as simple as it gets when it comes to basic house wiring. First of all we need to go over a little terminology so you know exactly what is being discussed.

Go to my Switch Terminology Page where I discuss the terms used for the different types of home electrical switches. It should also help in understanding the functions of each type of switch.

When wiring a 2-way switch circuit, all you're really doing is controlling the power flow (Switching off/on) to the load (a light, lamp, outlet, ceiling fan etc..)

Now a typical circuit will contain a 3-wire cable known as romex. The cable consist of a black wire, a white wire and a bare copper wire.

Black wire = Power or Hot wire
White wire = Neutral
Bare copper = Ground

When wiring a 2-way switch circuit, all we want to do is to control the black wire (hot wire) to turn on and off the load. This simple diagram below will give you a better understanding of what  this circuit is accomplishing.

2-way Switch Wiring Diagram

Now in the diagram above, The power source is coming in from the left. Notice the black wire is the only wire that we are controlling through the 2-way switch. You have an incoming hot wire (black) going to one screw (it does not matter if you use the brass or silver screw) on the side of the 2-way switch and a black wire from the other screw on the 2-way switch going to the load (light, ceiling fan etc..). The white wires are wire nutted together so they can continue the circuit.

Basic 2-way Switch Wiring Diagram

Now as for the ground wire. It is very important to connect the ground wire to the switch as well. The Green screw on the 2-way switch is for the ground so all ground wires should be connected as seen below.

2-way Switch Ground Connection diagram

All ground wires (bare copper) are all now connected (incoming ground, load ground and switch ground). This makes for a safe protected circuit by having all grounds intact.

So what have we accomplished. By wiring a 2-way switch, The circuit below shows the basic concept of electricity flow to the load. Let's assume the load you are controlling is a light. The electricity flows from the hot wire (black) through the 2-way switch (shown in off position) and then to the light and returns through the neutral wire (white). This is a completed circuit.

2-way switch electricity flow diagram

Now by understanding the diagram above, go up to the top diagram and by using the concept shown here, just use your mouse pointer on that diagram and follow the flow from black wire (hot wire) to the load and return through the white wire (neutral). This should give you a good basic understanding how the 2-way switch circuit works and will help you in adding or changing a 2-way switch.

So now that you have a basic concept of wiring a 2-way switch, let's look at the following 2-way switch diagrams to see which type of circuit scenario you have. After you have pulled your switch out from the wall, the wires in the box and connecting to the switch should look like one of the following.

Now by understanding the diagram above, go up to the top diagram and by using the concept shown here, just use your mouse pointer on that diagram and follow the flow from black wire (hot wire) to the load and return through the white wire (neutral). This should give you a good basic understanding how the 2-way switch circuit works and will help you in adding or changing a 2-way switch.

So now that you have a basic concept of wiring a 2-way switch, let's look at the following 2-way switch diagrams to see which type of circuit scenario you have. After you have pulled your switch out from the wall, the wires in the box and connecting to the switch should look like one of the following.

Basic 2-Way Circuit - Power Coming In At Switch

Basic 2-way Switch Wiring Diagram

Here you see the power is coming into the circuit through
the switch box, then to the light using a 3-wire cable.





Basic 2-Way Circuit - Power Coming In At Light

Power at Light 2-way Switch Wiring Diagram

Here you see the power is coming into the circuit through
the light box, then to the switch using a 3-wire cable.





Power Coming In At Switch - With 2 Lights In Series

2 lights with 2-way Switch Wiring Diagram

Here you see the power is coming into the circuit through the switch box, then to the double light boxes in series using a 3-wire cable for each light.





Power Coming In At Light - With 2 2-Way Switches and 2 Lights

2-way Switch with Lights Wiring Diagram

Here you see the power is coming into the circuit through the one of the light boxes, then to the light switches which are controlling each light individually, then on to the second light box. (Notice the hot side uses the "Red" wire from the first light. This is a 4-wire cable being used from 1st light to the switch box. The second light is only using a 3-wire cable). 





Power Coming In At Light - With 2-Way Switch and Outlet

Light and Outlet 2-way Switch Wiring Diagram

Here you see the power is coming into the circuit through the light box, then a 3-wire cable to the switch and a separate 3-wire cable to an outlet. (Notice the white wire from the switch is used as hot, therefore there is a piece of black tape on the white wire to indicate that it is being used as a hot wire).

Is the outlet switched or hot at all times? (Hot at all times. The hot wire is coming directly from the power source.)





Power Coming In At Switch/Outlet - With Light

Light with Outlet 2-way Switch Wiring Diagram

Here you see the power is coming into the circuit through
the switch & outlet box, then a 3-wire cable to the light.

Is the outlet switched or hot at all times? (Hot at all times.
The hot wire is coming directly from the power source.)






Allow Tim Carter from AskTheBuilder.com to show you
some great tips for installation and wiring a 2-way switch.