How to add motion sensor to outdoor lights with "OR" function?

I have existing outdoor light fixtures controlled by 2 switches. I would like to add an additional light fixture that turns on when:

1) The other lights are on
OR
2) Motion is detected

I am familiar with electrical wiring, but am not familiar with the myriad of switches in the market place.

Is there a device or combination of devices that will let me do this?

If I cannot mount the motion detector completely away from the lights, where would you suggest for a location that minimized problems caused by the lights?

Thanks,

Joe M

 

If I'm understanding you correctly. You want the new light to come on when the original lights are on..... or to come on by motion when the other lights are not on.

For a motion sensor to work it needs "always live" power. You don't have that. When the original lights are off there will be no power to make the motion sensor work.

 

PJmax,

Thanks for your reply. Your understanding of my desire is correct. Your assumption that I don't have "always live" power is not correct. I have lots of wire and am expecting a more complicated circuit.

One method would be to have a motion sensor activate a 1PDT switch. The "common" (not sure what you call it) lead would connect to the new light's switched-hot wire. The terminal for circuit-closed-when-activated wire would go to an "always live" hot wire. The terminal for circuit-closed-when-not-activated wire would go to the switched-hot wire of the existing lights. The new lights would then be on when the sensor was activated and the same as the existing lights when it was not.

A separate pair would power the motion sensor.

I can find a 1PDT relay activated switches with a 24v coil or a 120v coil (e.g., the 750-3C-120A from AutomationDirect.com). Most of the outdoor light sensors look like they would not have a problem with the 120V coil as their load. My problem is that these relays and their sockets are really not designed for residential wiring. I would need to build (get?) some large box to enclose it all safely.

I am hoping that someone would know of a device or devices that would simplify this. I don't know much about available devices and, as you can see, about the terminology used in residential wiring.

Thanks

 

Do you have access to the wiring from one of the switch boxes to the motion detector light?

If so, what I am thinking is to replace the three way switch that isn't fed power with a four way switch. Then run 14/3 (or 12/3) from the four way switch. Black wire goes to the terminal that will turn on all of the lights, red wire goes to the terminal that is on when all of the lights are off.

 

Ahhh..... good. We love complicated circuits. I'm just passing thru now but I'll stop back and leave more info for you.

 

caddymac,

I am having trouble understanding your suggestion.

1) Wouldn't your designations of the terminals on the 4-way near the load change every time the 3-way near the source was switched?

2) Do you say to have the black wire go to the load of existing lights and the red wire go to a lighting sensor and new light? If so, how would the new light be lit when the existing lights were on?

 

That relay you show is good. You could install it in a 4-11/16 junction box w/blank cover. It looks just like a 4" square 1900 box but is slightly larger.

You would run a three wire cable with ground....like 14-3 w/gr from the new motion location to the junction box. With that three wire cable.... black is hot, red is switched and white is neutral.

So in the junction box all you would need to do is short the red to black and your lights would come on. That's where the relay comes in.

 

1) Precisely. This is fine, as this is what you want - no matter what switch is used, all of the lights will turn off and the alternate circuit turns on.

2) This is where my plan falls completely apart. Yes, the black wire goes to the existing lights and to the sensor light after the sensor. The red would go to the sensor and then the sensor output would tie to the sensor light. However, doing it this way would back feed all of the lights from the sensor. Not a bad deal if that is what you want to do, but it doesn't sound like this is the case.

 

The scheme is to "transfer" the switched lead to the new fixture from a connection with the exiisting fixtures to a wire that is "live" when the MS operates.

This is effected with a single-pole double-throw three-terminal relay which has a "Normally Open" contact-terminal , a "Normally Closed" contact-terminal , and a "Common" terminal.

The lead to the new fixture connects to the "Common" terminal, and when the relay is "Normal" , i.e. , not operated, the "Common"terminal is closed to the "Normally Closed " terminal which is connected to the existing fixtures.

The MS will operate the relay, transferring the "Common" terminal to the "Normally Open" terminal , thereby illuminating the new fixture when the MS operates.

 

PJmax,

Thanks. Clearly explaned and looks like it will work. Confirms that I need to add a junction box with a relay rather than being able to find some device already built.

The main difference from my approach (and PATTBAA's) is to use the existing light circuit to actuate the relay rather then using the motion sensor to actuate the relay. This removes any concerns about problematic interactions between the motion sensor and the relay coil, but it now means that the relay may remain actuated for long periods of time. Should that be a concern?


PATTBAA,

Thanks. This sounds like my original approach. Any concerns about a coil load on a motion sensor rather than a lightbulb load?

Joe M

 

Look again Joe.....the relay is controlled by your existing house lights.
"To switch controlled lights" are the house lights.

There are RIB relays that will do what you want. They come in a plastic case with a 1/2"mounting stud for installing into a junction box. Low voltage (6-30v) relay coil models are 15-20 bucks. High voltage (120v) coils are like 65-70 bucks.....even on Amazon. That is un-reasonable.

 

Whoops! I thought I had posted a "thank you" back in June, but I don't see it. Sorry.

I got further into checking the existing wiring and found things I did not understand. I put the project on hold for the summer. Now I am back opening wiring boxes, removing some wallboard, and trying to reconcile the simplicity of paper schematics with the realities of pulled wires.

Until you pointed it out I did not realize that the circles in your diagram represented the relay coils (DOH!). Once that "clicked" everything was clear. Unlike your diagram, I don't have a single unit with both sensor and lights. My light is a sconce that is by itself. The sensor will be in a different place (and box). That allows me to have the relay activated by either the sensor or the existing lights. My tendency is to activate the relay from the sensor because the relay will be actuated less frequently and for shorter periods of time. I still have a concern about a relay activated for long periods of time when in an enclosed box. Should that be a concern?

The RIB relays that I have found look like they are designed with a nipple to mount on the outside of a box (e.g., RIBU1C). That sounds like an undesirable alternative where the box and relay are surface mounted. I would like to minimize the visibility. Are you saying I could get a bigger box and have the relay fit inside it?

Thanks for your help and patience,

Joe M

 

The first diagram is what I installed at my place about five years ago.
With the three way switch in the on position, both lights are on.
With the three way in the other position, the lights come on only at night when motion is detected.
The motion detector is also a light sensor.
I have not yet had any problems with it, if I turn it on, it will remain on for about five minutes after I turn it off, just as it would if it was the motion detector that turned it on.

In the second diagram, the Black, red and grey wires are the existing wires on your lights, not including ground, or at least what I picture them to be.
The blue and yellow wires are new wires, blue from hot on the switch, yellow represents white.
The motion detector will turn on all three lights.
Either three way will turn on all three lights, or turn them off with a delay similar to that which is normal for the motion detector.
Just be certain that you run a new line from the hot leg of the first three way, and not a new line from your breaker box.

 

Thanks Ed.

The relay seems to be needed because of a constraint in my problem. The motion sensor should only turn on the one new light and not the existing lights. The switches for the existing lights should turn on all lights. Your solution does not isolate the new light enough.

By the way, is your sensor separate from your lights? If so, where did you place it in relation to the lights so that it doesn't get confused.

Joe M

 

No, I didn't separate the sensor from the light that it came with, only wired a second light in parallel with the main one controlled by the sensor, and placed the three way switch as shown.
And you are right, neither of my configurations would provide the separation you desire.
It has been several decades since basic electronics for me, but it seems that there was some type of diode that could be placed in a circuit that would block electron flow in one direction, but allow flow in the opposite direction.

however, I look at the motion sensor as basically a make/break switch that "does not" have to be in the same location as the light that it controls, but should be able to be located just about anywhere in the circuit.

The motion sensor on the light I am using has three wires; Load, Line, and neutral.
So long as the neutral and line is connected to make the sensor itself work,
The load/light should be able to go from there to anywhere you want it placed.
You should feasibly be able to put a motion sensor outside, and the light controlled by it inside the house, thus letting you know that someone might be outside, and letting anyone outside think that someone was at home, but without letting the person outside be aware that it was him/her that activated the inside light.

 

Thanks Ed.

Diodes are really for DC circuits.

I wasn't concerned very much about where to place the sensor electrically. I was more concerned about the physical placement in relation to the sconce lights to avoid problems caused by the lights being too far into the sensor's fields of vision (PIR and dusk-to-dawn).

Joe