Installing Lightpads in a Multi-way Switch

(You can download the 3-way install walk through pdf at the bottom of the page.) 

A light that is controlled by more than one switch is called a multi-way switch.  The most common multi-way is a 3-way which is a light that is controlled by two switches such as at the top and bottom of the stairs, two sides of a hallway or two sides of a room.

Plum 3-Way Pre Installation Notes
Multi-way switches can be complicated to deal with. Before jumping in and removing switches, you must first consider a couple of things. We will focus on the most popular 3-way switch.

The key to success

If you can understand the following two paragraphs, the wiring will be easy and intuitive to you.  If the following sentences are confusing, don’t worry, we’ll still walk you through the installation process.

When wiring multiple Plum Lightpads into a multi-way switch, only one Lightpad will be physically connected to the light LOAD.  This is called the LOAD side Lightpad.  The LOAD side lightpad will have Hot, Neutral and LOAD connected (plus ground).

All other Lightpads in the multi-way circuit are not physically connected to the light or the LOAD side Lightpad.  These are called LINE side Lightpads.  LINE side Lightpads only need Hot and Neutral (plus ground).  They do not use the LOAD wire.  These LINE-side Lightpads will communicate with the LOAD side lightpad via Wi-Fi after all Lightpads are provisioned.

First we need to figure out the following.

1.Are you replacing existing 3-way.

2.What kind of switch are you replacing?
Is it standard dumb switch?
-Is it a dimmer? If so is it electronic?
-Are the switches in a multi-gang box?

All of these conditions can impact the appearance of the wiring when removing the existing switches.

To be successful, you must find the HOT wire and the LOAD wire for your 3-way switch.  For this discussion, we will use the term “box” to indicate the plastic or metal back-box into which the switch is installed.

Standard 3-way switches usually have a Hot wire in one location and the Load wire at the other location.  However, it is possible that both are in a single box or that Hot is in both boxes. Typically, two traveller wires are used to complete the circuit between the two. Standard switches do not require a Neutral wire so they are usually in the back of the box capped with a wire nut. Depending on on what wires are available at each location, it me be necessary to re-purpose the Traveller to supply Hot, Neutral, or both from one location to the other.

Here are some common situations we have run into when installing 3-ways.

1. In the best case scenario, there will be Hot, Neutral, and Ground in both locations and the load wire in one of the locations. This is usually the case with multi-gang boxes.  The Plum Lightpad only requires the Load wire at one location – we call this Lightpad the LOAD-side Lightpad. The other Lightpad’s Load wire is not used and is just capped with a wire nut.  Only the Lightpad connected to the Load will control the light immediately. The other will need to be provisioned first. Multi-gang boxes are the most challenging but the install is the same. Since there are multiple switches and more wires, it can add confusion.
2. In some scenarios, both locations could have Neutral but not a Hot wire. In this case you would repurpose one Traveller to carry the Hot to the box where it is missing.
3. Another scenario only 1 location will have Hot and Neutral.  So both Traveller wires are repurposed to carry the Hot and Neutral to the other switch.

Once the switches are installed only the switch driving the Load will control the Light immediately. The 2nd switch must be provisioned using the Plum app.

Provision the Master switch driving the Load then provision the second switch and choose the existing Light with the name of the 1st switch. This becomes the Aux switch which is essentially a remote for the Master switch. As long as they are connected to the wifi network, the Aux will control the Light via the wall switch.


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