I have a car port which has 8 flood lamps installed in the ceiling. I have recently installed an occupancy sensor switch similar to this Lutron Maestro MS-OPS5MH-WH:

http://www.lowes.com/pd_365253-539-MS-OPS5MH-WH___?productId=3531524&pl=1&Ntt=motion+sensor+switch+three+way

It required using a jumper cable at the other end of the switch. Previously, three cables ran to that switch, but the motion sensor docs instructed to combine two of those with a short "jumper" cable it provided with a wire nut, and then run that jumper and the last pre-existing wire to the switch...effectively leaving just two wires connected to the switch.

The intent was to have the occupancy sensor switch the lights on only at night to prevent car break-ins. The switch has a built-in ambient light detector which is supposed to prevent it from operating by day, but it doesn't work well at all, perhaps from the shade provided by the car port cover.

So, I thought I'd try a timer switch on the other side, so I could set the switch to only operate during night hours. I purchased the Intermatic ST01 (http://www.intermatic.com/en/products/timers/inwalltimers/electronic_timers/st01_series). However, this switch requires a similar configuration on the remote end (using a jumper wire to wire the two of the three cables, together, etc).

Is is possible to use these switches in combination? If so, how should one wire this? And if not, could you explain in layman's terms what the jumper wire does and why it's impossible to use two switches which require the jumper wires together?

Thanks!

  • It sounds like each of these switches need power all the time and the line that feeds the power also feeds the load. Combining switches in conventional wiring requires them to be in series. Given that each switch always needs power, and the logic portions are not isolated from the load portions means that the downstream switch will lack the power it needs to do its job. Sounds like a non-starter. Do you have wiring diagrams for these? – bib Jun 1 '16 at 21:56
  • Can you post photos of the insides of both boxes? – ThreePhaseEel Jun 1 '16 at 22:17
  • @bib the wiring diagrams are searchable but it's a lost cause. Both devices have you reconfigure the 3-way wiring to make one messenger always hot and the other switched-hot, which the device listens to as a data signal. They're both designed to wire in series with no neutral. Also beware the words "similar to"... What does that mean, similar in features, similar in wiring etc. – Harper Jun 2 '16 at 0:32
  • @Harper Basically the problem requires an AND configuration, but the wiring is setup for an OR. – bib Jun 2 '16 at 0:36
  • 1
    I was kidding about the Arduino lol... Yes the modern home automation stuff would help, but so would a decent sensor. – Harper Jun 2 '16 at 2:13
up vote 3 down vote accepted

Keep in mind, you're asking quite a lot here. You want a 3-way switch (why?), and a motion sensor, and also a time of day timer only because your sensor is not performing to your satisfaction. Also you are driving 8 flood lights which I suspect exceeds this sensor's rating. And you bought a "no neutral" switch which makes me think you don't have a neutral.

Let me be blunt: it isn't gonna happen like that. It can't.

3-way switch

First, think through this "3-way" business. How is that supposed to work? If you throw that switch, will the light come on for 5 minutes? All night? Forever? If it's already on, does it turn off and if so, when does it revert back to sensor control? What if you throw the switch in the daylight? You're pretty much at the mercy of the motion sensor to define what that does, and it may not be what you want.

If you need better motion sensor coverage, that can be had by configuring multiple motion sensors. That, however, requires neutral to the sensors and 2 hot wires between them.

Daylight sensor.

Not turning on during daylight is one of the most basic functions of an exterior motion sensor. That feature is not as common with an interior sensor, but it should Just Work, you shouldn't have to tell it twice.

That said, the better daylight sensors have to "learn" what daylight is. Consider sensor A, directly under a streetlight illuminating white concrete, and sensor B which is deep in the back of a carport: Sensor A may see more light at night than sensor B sees by day. As such, both sensors need to "learn" what a day-night cycle looks like, for them. They have internal clocks and memory, and record hour-by-hour luminance averages over several days, and figure out which hours are dimmest. I bought a cheapie Christmas tree light controller and installed it on a dim porch, first day, it ran the lights all day. By day 3 it had figured out what "night" was.

Trouble is, when you cut power to one, it loses its memory and starts over. That can happen from experimenting, or a miswired 3-way switch, or an upstream timer shutting it off.

TLDR: give your motion sensor 3 days uninterrupted to get oriented to what "night" is. If it still doesn't work, get a better one, perhaps one listed for exterior use, and perhaps one made to take neutral if you have that.

Neutral

If you have access to neutral, consider using sensors that use neutral. These wire very simply: aside from ground and neutral, they take an "always hot" connection and a "switched hot" connection like a plain switch. They have a guaranteed always-on power supply (via always-hot and neutral) so they remember... And since they're not leaking power through the bulb, they work fine with any bulb type. Simply put, neutral-using sensors are better in every respect. You can parallel several sensors or switches; if any is on, the lights are on. Between power supply and your last sensor, you need 2 hots and a neutral (14/3 wire).

LED

With 8 lights, you are pushing the capacity limits of many sensor switches unless you use LED. I recommend you do. Price and selection is quite good now. However many non-neutral sensors don't play well with an all-LED circuit. The workaround is to leave one incandescent in the circuit... which works until it burns out, which they frequently do... So use two.

  • Thanks Harper. The reason I was doing it three-way is that was the way it was already wired...a switch outside on the car port itself and another inside the house for control. I didn't realize that the sensors learn over time...perhaps switching the inside switch on and off has caused problems with that learning...I'll verify the make/model and see if does indeed learn. If not, I'll explore other switch that do support this learning and just instruct the family to never cut off the indoor switch. However, at this point, I'm leaning towards z-wave to accomplish my goals. Thanks again! – jbwiv Jun 2 '16 at 2:23

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