I am looking to replace one my 3-way toggle switch to a 3-way sensor switch (Leviton DOS05). After wiring per instruction provided, the second switch (non-sensor) does not work unless the sensor switch is on.

Here’s a wiring diagram of my setup:

enter image description here

When I tested the lines with a voltage pen, both travelers do not have any voltage reading when the sensor is off. I'm pretty certain that the load and line wires are installed correctly, so I'm not sure if there's an issue with my 3-way sensor switch, or if this is a case of incorrect wiring.

Toggle switch: enter image description here Sensor switch: enter image description here

1 Answer 1


Based on the installation instructions, I think you have most of this correct, as wacky as it looked to me at first.

However, there is definitely one thing wrong: Line vs. Load.

Line refers to incoming power. That is, if you have all the wires separated out and not attached to anything and turn on power, that is the one wire that will have power.

Load refers to outgoing power - i.e., to the light fixture.

According to the instructions, load should be in the sensor box and line should be in the regular switch box. Which is what your diagram shows. Except that you have the light fixture connected to line. Which would be wrong if that were the case. But based on the diagram, I think you actually have line and load reversed - i.e., the wire going into the sensor box - showing with an arrow towards the sensor, implying that it is incoming power - marked as load. If indeed the two are swapped then effectively the sensor is the first switch, controlling whether any power is going out to the second switch and then to the light. Some smart 3-way switches work that way, but this one works the opposite way - power first to the ordinary switch, which sends power on via the travelers to the sensor switch.

The way it works is that the ordinary switch is wired so that there is always power on Traveler 2. There is also power on Traveler 1 in one of the switch positions ("up" in the example wiring diagram). So the sensor switch is actually powered by Traveler 2 (which is why that is labeled as "Line/Load" on the sensor switch) and Traveler 1 is used as a signal, and in fact is labeled as Traveler (singular, no #) on the sensor switch. This actually means you could use a standard (not 3-way) switch in place of the "ordinary 3-way switch" and it would work just as well, as long as it was wired in a matching fashion. The instructions don't list it that way because for retrofit purposes the assumption is that you already have a 3-way switch in place.

Can this be fixed? Maybe. It depends on what wires/cables you have in each box. It may be very simple to rearrange things, or it may be hard. I am pretty sure it will be possible, assuming you have a typical /3 with ground cable in between the two boxes, because you are not relying on neutral (this switch can work using ground instead of neutral) so there should be a way to make it all work. Need annotated pictures showing the wiring in both boxes to figure out a complete answer.

  • Thanks for the clarification! You are right that I incorrectly annotated the line and load, and that the sensor switch is connected to the line wire instead of the load wire specified in the instruction sheet. If I wanted to keep this wiring configuration, would the only solution be to use a 3-way sensor that works with a line connection?
    – Steve
    Commented Nov 26, 2023 at 18:43
  • Not necessarily. It is possible that the wires can be rearranged such that it could work "in reverse". But unknown without a lot more detail - e.g., pictures of the actual switches/wires. Commented Nov 26, 2023 at 19:28
  • 1
    Hi there, I've added wiring pictures for both switches, would this be sufficient?
    – Steve
    Commented Nov 26, 2023 at 20:22
  • That does help a bit. A couple of questions: 1 - Are the wires loose individual wires in conduit, or are they sets (black/white, black/red/white) in cables? 2 - It sure looks like you have neutrals, why aren't you using them? Commented Nov 26, 2023 at 21:01
  • I’m not too sure whether the wires are set or individual. The original switch (and the whole house) wiring was done by the electrician and he wired the switches without neutral. I followed suit to be consistent since the sensor switch didn’t require neutral either
    – Steve
    Commented Nov 26, 2023 at 21:45

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