3-way smart switch wiring

[Stevekester]

Hi, I am trying to wire a smart 3-way switch but the manual diagram does not make sense. Attached are photos of my existing switches and the wiring diagram from the manual. Which of my existing 3-ways do I swap out and which wires go where?

Thanks, I’ll owe you!

 

[Lucien Nunes]

Excluding grounds, the smart switch needs a minimum of three wires to operate - hot supply, neutral and switched hot (=load). At the moment, there is no neutral in the switch boxes (unless there are other wires we can't see in the pictures.) One switch has the hot supply and sends two travelers to the other switch, from which the switched hot returns to the light.

To configure for just the one smart switch and disable the other switch position, the wires leading to the smart switch need repurposing at the junction box or light fixture, from hot/traveler/traveler to hot/neutral/switched hot.

The smart switch allows for the 'other' switch of the original 3-way to control it remotely. That requires a 4th wire from the smart switch, shown in the diagram as the blue wire labeled as a traveler, along with a hot, to be sent to the remote switch. But as you only have 3 + ground, this option is not available to you without extra wiring.

 

[Stevekester]

Excluding grounds, the smart switch needs a minimum of three wires to operate - hot supply, neutral and switched hot (=load). At the moment, there is no neutral in the switch boxes (unless there are other wires we can't see in the pictures.) One switch has the hot supply and sends two travelers to the other switch, from which the switched hot returns to the light.

To configure for just the one smart switch and disable the other switch position, the wires leading to the smart switch need repurposing at the junction box or light fixture, from hot/traveler/traveler to hot/neutral/switched hot.

The smart switch allows for the 'other' switch of the original 3-way to control it remotely. That requires a 4th wire from the smart switch, shown in the diagram as the blue wire labeled as a traveler, along with a hot, to be sent to the remote switch. But as you only have 3 + ground, this option is not available to you without extra wiring.

Lucien, very helpful, thank you. So if there was an un-used common wire in the box, I could use that between the switches?

 

[Megawatt]

Excluding grounds, the smart switch needs a minimum of three wires to operate - hot supply, neutral and switched hot (=load). At the moment, there is no neutral in the switch boxes (unless there are other wires we can't see in the pictures.) One switch has the hot supply and sends two travelers to the other switch, from which the switched hot returns to the light.

To configure for just the one smart switch and disable the other switch position, the wires leading to the smart switch need repurposing at the junction box or light fixture, from hot/traveler/traveler to hot/neutral/switched hot.

The smart switch allows for the 'other' switch of the original 3-way to control it remotely. That requires a 4th wire from the smart switch, shown in the diagram as the blue wire labeled as a traveler, along with a hot, to be sent to the remote switch. But as you only have 3 + ground, this option is not available to you without extra wiring.

 

[Lucien Nunes]

So if there was an un-used common wire in the box, I could use that between the switches?

Yes, you have to get one wire from the smart switch to the remote that does not connect to anything else, plus the hot feed that can be either from the smart switch box, light fitting or other junction box on the circuit.

 

[Stevekester]

Yes, you have to get one wire from the smart switch to the remote that does not connect to anything else, plus the hot feed that can be either from the smart switch box, light fitting or other junction box on the circuit.

THANKS! Last question: how does one determine with switch connects to the light?

 

[Lucien Nunes]

It's impossible to tell from here without more pictures / info, not least because we can't see how many separate cable runs are present at each switch location, and what other functions they are used for (e.g. the other half of that 2-gang). There are many different permutations, some of which would work for you and others not. You might need to look at what is present at the box in the ceiling to confirm feasibility.