Installing Wi-Fi Smart Switches

Smart Switches vs. Smart Bulbs

In my ongoing quest to turn my house into a smart home, I decided to replace many of the important light switches with Leviton Wi-Fi Smart Switches or Dimmers. I chose to use Wi-Fi switches/dimmers instead of smart bulbs for a few reasons:

Bulbs require forfeiture of the usage of any existing light switch functionality
Light switches allow you to control other motors/appliances, like ceiling fans (which our house has)
Smart bulbs require an additional hub (one per 9 bulbs for Philips Hue), using up precious real estate
I wanted to replace the existing switches with Decora style switches anyways
Fewer always-on devices constantly drawing power
Smart switches require a neutral (white wire), since they need to draw power, which is available most if not all of our light switch boxes

Smart bulbs make sense to me in a few scenarios:

Rental property where you do not want to make the investment into smart switches
You are not comfortable wiring a new light switch
You didn’t really use the switches anyways
You don’t plan on staying in your current home very long and want to bring the smart devices with you when you move
A neutral (white wire) is not available in the light switch box

Safety & Terminology

Electricity is dangerous when handled incorrectly. The first thing you should ALWAYS do when starting any electrical project is shut off all power in the boxes in which you will be working. Some tools that can assist with this are a circuit breaker finder, a voltage tester, and a GFCI tester. Find the right breakers/fuses and shut off the power to any circuits that go through/into the boxes in which you will be working.

Some common terms that will be used in this post:

Line: The source of the power. Also refers to the wire coming directly from your electrical panel. Usually black or red.
Load: The consumer of the power. Also refers to the wire going to the motor, fan, light, fixture, etc. that will engage when the switch is turned on. Usually black or red.
Ground: The wire that is used to return power to the ground in the event of a short/fault. This is a safety measure to protect against electric shock. Usually bare (unsheathed) or green.
Neutral: The wire that is used to return power to the electrical panel and complete the circuit. Usually white.

Single-Pole and Three-Way

A “single pole” light switch is your standard switch configuration: a single switch controls a downstream circuit. Think of a light switch that controls the lights in your bedroom. There are two primary methods of wiring a single pole switch:

Power passes through the switch on its way to the load (light/fan/fixture/etc.). In this case, the neutral (white wire) is available in the same box as the light switch. This is common for switches installed when the structure was built.
Power goes directly to the load (light/fan/fixture/etc.) and a leg is run down to the switch. In this case, there is often no neutral (white wire) available in the same box as the light switch. This is more common for retrofit installations. THIS IS INCOMPATIBLE WITH LEVITON SMART SWITCHES.

A “three-way” light switch is a more advanced configuration where multiple switches can control a single circuit. A common case for this is light switches around a staircase, entryway, or other pass-through room. You may want to turn the lights on at the bottom of the stairs and then turn them back off at the top of the stairs. A three-way switch works in concert with another three-way switch by alternating the power between multiple “traveler” wires. When both switches are connected to the same traveler, the load (light/fan/fixture/etc.) is powered. For 4-way switching, the wiring diagram is considerably more complex.

A three-way switch setup consists of a line switch (the switch that is closest to the electric panel) and a load switch (the switch that is closest to the fan/light/fixture/etc.). The traveler wires transmit power from the line switch to the load switch.

Single-Pole Wi-Fi Switches

Wiring a single-pole Wi-Fi switch is straightforward. Disconnect the existing switch and connect the Wi-Fi switch in the same manner. The primary caveat is the need for an additional neutral (white wire) in order to power the switch itself.

The basic steps are:

ALWAYS: Shut off power at the electric panel in your house, verify that power is cut with a voltage tester
Remove old switch
Connect the hot wire (black wire coming from electric panel) to the Black terminal on the new switch
Connected the load wire (wire going to the fan/light/fixture/etc.) to the Red terminal on the new switch
Do not connect anything to the Red/Yellow terminal on the new switch, this is only used for three-way applications
Connect a neutral wire from the White terminal on the new switch to the other neutral wires in the box with a wire nut
Connect the ground wire (bare or green wire) to the ground terminal (green screw) on the new switch

Three-Way Wi-Fi Switches

Leviton’s Wi-Fi switches can be used in a three-way configuration (in fact, up to 9-way based on their documentation). But there are a few catches to this:

All of the switching is performed by the main Wi-Fi switch (Leviton DW15S-1BZ)
Additional switching locations are facilitated by a “coordinating remote” (Leviton DD0SR-1Z)
You cannot use a traditional three-way switch in the remote switching locations; this will result in your fan/light/fixture/etc. flickering or toggling on and off very quickly
All switching locations require a neutral (white wire) to power the switch

In other words, there is only one Wi-Fi switch and the coordinating remote(s) just send a low voltage signal back to the main switch. This makes sense when you consider the following:

If all coordinating remotes were also Wi-Fi switches, you would end up with many unnecessary Wi-Fi devices on your network
Multiple switches controlling the same device would make voice control difficult to manage, specifically addressing individual devices
The wiring is far simpler if switching happens in only one location
The coordinating remotes do not need to know the current state of the load (fan/light/fixture/etc.), just the desired state (i.e., if you push the switch up or down)

The primary issue you can run into with replacing three-way switches with a Wi-Fi switch is that there is no neutral (white wire) in the box for the coordinating remote. If this is the case, you have two options:

Leave the existing switches in place (or replace with traditional Decora style three-way switches, i.e., not Wi-Fi switches)
Reconfigure the wiring to a single-pole wiring situation

Three-Way Wi-Fi Switch

In order to replace an existing three-way switch setup with a three-way Wi-Fi switch setup, it will require the following:

Replace line switch with the Wi-Fi switch, following the instructions for single-pole application with the following changes:
- The red terminal should be connected to one of the travelers, heretofore traveler 1The red/yellow terminal should be connected to the other traveler, heretofore traveler 2
Replace the load switch with the coordinating remote
- Connect traveler 2 to the red/yellow terminalConnect traveler 1 and the load wire with a wire nutConnect the white terminal to the neutral wire(s) in the box with a spare wire and a wire nutConnect the ground (bare or green wire) to the other ground wires in the box

Converting Three-Way Switch to Single Pole Wi-Fi

Let’s take another look at the wiring diagram from above for how three-way switching works:

At a high level, all we need to do is eliminate one of the travelers, remove one of the switches, and replace that switch with a permanent connection between the common and the remaining traveler. For the purposes of this explanation, we will remove switch 2, eliminate traveler 2, and connect traveler 1 to the common. This assumes that box for switch one contains the neutral (white wire). The basic steps are:

ALWAYS: Shut off power at the electric panel in your house, verify that power is cut with a voltage tester, ensure that you have shut off all power sources in the box, as a three-way switch box may contain multiple distinct circuits
Remove switch 2
Cap traveler 2 at both ends with wire nuts
Join traveler 1 to the comment present at switch 2 using a wire nut
Replace switch 1 with Wi-Fi switch, following the stops above for single-pole wiring
Cap the box that formerly contained switch 2 with a blank wall plate