Introduction to the Smart Switch
A smart switch is a key element of a smart home. Before getting starting with wiring, be sure to familiarize yourself with the articles on the introduction to wiring and basic (non-smart) switch wiring. Smart switches work exactly like the basic light switch – the black wire goes through the switch and is toggled on or off by the switch. The white wire goes to the light. But the only difference is that the smart switch itself also needs power to operate. Whereas a basic light switch does not (it needs no power to toggle the black wire open or closed). The white wire must also be connected to the smart switch, so that it too can have power. The white wire usually passes though the switch junction box, as shown in the diagram above.
Need for Neutral (white) Wire Needed
Some home wiring may not have the white (neutral) wire in the switch junction box. A neutral wire is needed to power a smart switch, and without one, you will not be able to install a smart switch without pulling wires.
Step-By-Step Instructions for Wiring a Smart Switch
Once you understand these basics, the instructions that come with the switch and the connections required will make more sense. Figure 2 below shows the wiring diagram for a single smart switch. Here are the step-by-step wiring instructions:
- Power off. Always be sure to turn the power off at the breaker before starting any wiring work.
- Connect the black wires (line and load) to the terminals on the left side of the switch. The black wire that goes to the light connects to the top terminal (load) and the black wire from the circuit box connects to the bottom terminal (line). These are the same black-wire connections that you have on your old switch. So just transfer them over in-kind.
- Connect the white wire (neutral). For the white wire, it is necessary to splice off the existing white wire inside the box (extra wire conveniently comes with the smart switches). Connect the spliced white wire to the bottom right terminal (neutral). This wire is necessary to provide power to the switch itself.
- Connect the ground wire to the ground terminal.
Note that the terminal in the top right of the switch labeled “traveler” has a piece of tape over it. It is for three-way switch wiring, which is covered below. It is not needed for wiring a single switch.
That’s it. A lot of explanation for a very simple wiring job that involves connecting a few wires to the proper nodes. Below are some photos of the wiring of one of my single smart switches.