Here’s the scenario: we want to use an occupancy sensor switch to turn the lights on in the mud room. The thing is, we want to turn them on from two different places. It’s already got 3-way switches for doing this manually. I can imagine how to change this to occupancy sensing switches but I don’t know if it will blow out the switches.

A 3-way switch setup would have power in one box, the load in the other box, and two “travelers” between the two boxes. I won’t go into how to wire this for what’s called three-way operation.

I envision renaming one traveler as “power,” the other as “switched leg.” Then, in each box, I wire up an occupancy sensing switch. Both have power from the power wire. The different part is what to do with the switch outputs.

Each occupancy sensor’s switched output goes to the switched leg and to the load. The lights go on no matter which door you come into.

This setup connects the outputs of the two switches together. The question is this: will 120 volts out of one switch damage the output circuitry of the other switch when its output is at zero? If not, then walking in either door turns on all the lights and this does what we need.

Yes, both switches have the same hot from the same phase and breaker. I can’t think of any details to make this more clear.

Thanks for any input you may have on this. Experience is preferred to wild-ass conjecture.

Hi Ernie,

I know exactly what you're trying to do but I'm wondering if the answer to your question may be manufacturer-specific. When one occ switch is on and the other is off then the "off" one is getting 120 volts fed into its output. On a regular switch - no problem. But with these you have electronics involved which may or may not be damaged - either right away or over time.

Why not avoid the chance of this happening and install two Lutron wireless Maestro controls and as many wireless occ sensors to cover the area (wall or ceiling mount). You'll get better coverage because you can mount the sensors anywhere instead of having to rely on the existing locations of the switches.

[Link: lutron.com]

Thank you!
You awoke me to the fact that I left some things out (first time texting on an iPad).

Why not do as you propose? Because we’re improving on existing 3-way switching.

Why not use a different product? Because we already have a pair of Lutron Maestro MS-OPS2H and a couple of 4 ft fluorescents (I hadn’t even thought about that!). Now I need to go look up 2 A ballasts....

Just wire the sensor in parallel with each other...

[Link: renovation-headquarters.com]

[Link: diy.stackexchange.com]

Or take at look at the response in this thread...

[Link: forums.lutron.com]

KOT

That is EXACTLY the issue. THE question. THE SUBJECT, if you will.

While thinking does not always reveal the truth, here are the thoughts: When switch A is on:
If switch B is on, there should be no problem as both outputs come from the same input.
If switch B is off, then the input to switch B will be at 120 v, and the output to switch B (coming from switch A) will be at 120 volts.

What could go wrong?

Take a look at page 3.

[Link: lutron.com]

I know you have a couple of OPS2H, but you could always use them some where else.

KOT

KOT,
There’s nothing I can do with the sensors because the sensors are inside the units. When the Lutron note discusses that you cannot parallel two sensors, it’s irrelevant: they’re sealed up inside the unit. All I can connect to are two leads meant for 120 volts, an input and an output. FWIW, they are not even labeled input or output!

The question is about two units as named above. I know you’re trying to solve my problem, but you’re not sticking with the actual question: can the outputs of THESE PARTICULR occupancy sensors be tied together?


KOT,
That page 3 note is about one sensor and two control locations. Thanks, but wrong scenario.

I looked at the page 3 again. I just saw the two occupancy switches and assumed that they were wired together. Not realizing they were images for different models.

As for what I was saying to wire them in parallel. I am talking about the entire units, not just the sensors inside the switch.

KOT

You know how you go on and on about how having all the information is important? Well, in a similar way, having the right tool to do the job is important. Looks like you picked the wrong tool for the job. Now, you can possibly figure out a way to hack something together with lots of wasted time, but it would probably be more efficient to scratch the Maestros and pick the right parts for the job at hand.

I was thinking the same thing. This will also add a terrific upgrade path vs the current science project

First, I'd pay no attention to the three links from KOT because:

- Two of them are DYI sites (what could go wrong?)
- The other one from the Lutron forum has an answer which doesn't understand the question! In his wording he is describing powering the 2nd occ sensor from the output of the first one. That's not what we're talking about. I think I'll log into the Lutron forum and explain the wiring and then ask what would happen.

On Lutron's web site there is this FAQ (multi location control):

[Link: lutron.com]

But it doesn't say why you can't.

The model you have is the one without a neutral but does require a ground wire to work. This is because the electronics of the sensor needs a return path. This is not allowed in the NEC because it puts current flowing on the equipment grounding conductor. Magically, the manufacturers found a way to persuade UL to make a listed product which doesn't need a neutral. It still violates the intent of the electrical code but if you're a rich corporation there's always a work-around!

Thanks, David.
A crucial point is that the Lutron note you linked to talks about a Lutron In-wall Sensor, while we're talking about an Occupancy Sensor Switch, that is, the sensor is buried inside the switch enclosure, with no access to the actual sensor wiring. As you saw, that means is no possibility of putting the SENSORS in parallel.

People normally don't put lighting and outlets on the same breaker, but I bet there will be complaints, and I can even see this product being recalled, if anyone ever installs a MS-OPS2H on a circuit protected by a GFCI. It should instantly pop a GFCI.

Or am I wrong and lighting circuits must be separate from outlet circuits?

[Link: lutron.com]

No. The MS-OPS2 is for single pole applications only. For 3-way applications, you'll need to use an MS-OPS5M sensor with either a companion switch (MA-AS) or a mechanical switch. For applications larger than a 3-way, you'll need to use companion switches in conjunction with the sensor switch.

NOW you've arrived at the place I was at when I asked: will it work to wire theze guys in parallel? If you go back and read through this thread you'll see where we are:
*Nobody answering the question, not even Lutron.
*Several suggestions of alternate things that don't meet the criteria: turning on a set of lights, using existing three-way wiring, with two Lutron Maestro MS-OPS2Hs, one in each location that now has a 3-way traveler wire in it.

Tell me yes, tell me no, but talk of other things is of no help.

If you have an occupancy sensor (or two of them), why do you need three way switching? Assuming the sensors are to avoid the need to manually turn the lights on (and this is the reason I installed a motion sensor switch in the laundry area of my house), the sensors will do what you need without requiring the more complex wiring. You could rewire at one end to eliminate the switch.