Looking for a light switch that can turn of/off manually AND on/off by motion. I can find those. Here is the trick. I have a number of rooms with ceiling fans. Is there a switch that allows zones so I can get it to ignore motion above a certain level?
The short answer is no.
The longer answer is that you may be able to mask the lens on the switch, such as putting a piece of white tape across the top half of it, which will change the detection zone. This just depends on the specific model and might require some trial and error.
The other alternative is to use two different devices, a motion sensor which you can put anywhere you want and a smart switch. Then it’s quite easy to put the motion sensor somewhere where it won’t trigger from the fan, even on the ceiling just outside the room so it catches you as you enter. Or inside a box or tube to get a very directed detection zone.
As I’ve mentioned before, I use a motion sensor inside a small box on the shelf pointing up so I can wave a hand over it and have a touchless switch. Other people put a motion sensor underneath a sofa or bed so it only detects motion at floor level, such as someone walking through the room.
Once you use two different devices you have a lot of possibilities.
Interesting. Are you actually experiencing an issue with a ceiling fan triggering a motion sensor? I have ceiling fans in seven rooms that are in line with motion sensors and they never trigger the sensor. The motion sensor should be reacting to heat changes across its ‘view,’ nothing else.
Thanks for the quick response. I had though of that, but I have quite a few ST devices and find the lag time troublesome. A Ring camera detects motion and I get the alarm 2-3 minutes later. I have a couple of lights set up for geo-fencing. I can get home and walk in the house before the lights come on. It does me little good to have a motion sensor detect me entering a dark room, but the light doesn’t come on for 2-3 minutes.
The two examples you give should work, but I want the light to go of when motion is no longer detected. A switch in a box won’t do that. A detector under a sofa won’t work because, when my wife in on the sofa, her feet are on the sofa.
AH-HA!!! No, I haven’t tried one yet. I presumed a ‘motion’ sensor meant it detected motion. Everything I’ve read mentions '‘motion’ only. If, in fact, it’s heat, that solves my problem. Umm, how far away does it detect heat? 20 feet, I hope.
Range varies by brand/model. Typically a sensor will detect motion to the other side of a typical sized room. But orientation will also determine.
Motion sensors are most effective at detecting motion moving across its line of sight, rather than moving immediately towards/away from it. But generally they are sensitive enough to detect most motion. And yes, they detect motion by sensing minute changes in heat. So for example, if you threw a book across its path (and it does not see you actually throwing) the book itself will not set it off. A ceiling fan certainly shouldn’t either.
The fan itself can set off the motion sensor if the motor gets hotter as it operates, although that’s pretty rare.
However, it is very common for a fan or air conditioner moving air through a room to set off a PIR motion sensor because of the change in air temperature in different airstreams.
It just depends on the specific placement. If it’s not happening for you, that’s great, but it certainly could happen for someone else, particularly if warm air is being pulled in from another part of the house.
There are different kinds of motion sensors. The ones most commonly used as standalone sensors with inexpensive home automation systems are “PIR”, “passive infrared.” They are detecting heat, but it is really minute changes in heat. For example, a cloud going across the sun can create enough of a temperature differential that the sensor will trigger once the cloud has passed. This is also why this particular type of sensor is prone to false positives.
As far as the size of the detection zone, the first rule of home automation applies: “the model number matters.” Different models have different size zones, anywhere from about 3 m to about 20.
The ones that are built into light switches typically have a detection range of about 5 m, intended to catch someone walking into the room.
see the FAQ:
The motion sensors which are used with cameras are typically a different technology using video analysis. those are true motion sensors.
Well, I’m in TX, it gets hot so I’ve definitely got heat in the rooms being moved and the fans can be on for a very long period of time. But thus far I’ve never noticed a motion sensor triggered from just a fan running. So, yeah, guess I’m lucky. But something tells me if fans were responsible for triggering motion very often we’d hear a lot more about it in here.
Now I have it the other way - if motion detected for more than a certain amount of time and temp is above x set fan on …
Well, what I want, ideally, is a light switch with built in motion that will detect motion (heat) when someone enters a room and stay on until the person leaves (motion/heat stops). If, in fact, motion detectors detect heat, I’ll look for one with a 20’ range. If it detects actual motion, that’s more problematic until I get more testimonies.
“PIR sensors” detect heat (the PIR stands for “passive infrared).
But there is a motion component: it is a minute change in heat passing across the detection field. Once the heat has been detected initially, It doesn’t continue to trigger the device
This is why, as the FAQ explains, these sensors are much more effective when someone is walking across the field at 90° than when they are walking straight on towards the sensor. Because there’s no change in heat when you are walking straight on. It’s the change that the sensor reports on, not the heat itself.
Thanks. what I want is a sensor that will detect motion or heat when I enter a room and stay on as long as motion/heat is detected. Will any sensor do that or am I after something that doesn’t exist?
That’s not how residential home automation battery operated sensors work.
In order to preserve battery life, these sensors “sleep“ most of the time. They wake up every couple of minutes and “sample“ the environment to see what’s going on. It’s typically once every three minutes, but some are different and some have a variable you can set. (But the more frequently it samples, the quicker you use up the batteries.)
So the sensor is asleep. It wakes up to check what’s going on and it detects heat passing through the detection zone. It sends a “motion detected“ report to the hub.
It goes back to sleep. Three minutes later, it wakes up again and checks what’s going on. If this time it doesn’t detect anything, it sends a “no motion detected“ report to the hub. And it goes back to sleep.
And then it just keeps cycling that way forever.
So you’re asking a question in a specific technical way, but it’s not really the use case you want.
The use case you want is “is there a sensor which can detect when someone is moving in the room and turn on the light, and then turn the light off again later after a period of no activity?
And the answer to that is sure, there are dozens. That’s just “motion activated lighting” and it’s a very popular use case.
You may have to use more than one sensor depending on exactly where people are sitting to make sure that the system still knows there is someone in the room if they are, say, sitting on the couch.
And some individuals sit so still that they don’t have enough activity to alert the sensors. In that case, you may need to combine it with a different kind of sensor, typically a pressure mat under the sofa cushions or device that can monitor when the TV is on. So that counts the TV has activity in the room.
There are lots of ways to handle it, sometimes it’s just trial and error to see what the patterns are in your own particular household.
But in general, you’ll get the most useful answers if you describe what you want to accomplish rather than the technical bits of how you want to accomplish it. Because there may be lots of different ways of accomplishing it.
That clarifies my search some, but, remember, my original question was looking for a motion sensor within a wall-mounted light switch. Thus, no battery. And NOT activated by a ceiling fan.
Followup. If I find I must use a separate sensor for motion to turn on the light, any method to find out lag time? I don’t want to walk in a room, sit in my chair, pick up a book, and THEN the light comes on.
Good point. You are right, a mains powered sensor probably doesn’t have a sleep cycle. But it still doesn’t typically monitor continually, for one thing, that would flood your network with Messages. So there’s still usually a sampling cycle, it will just be shorter.
As far as lag time with a battery powered device, that will be listed in the specifications, as well as whether it is configurable. So usually you need to read the user manual for the device as part of doing Your research. But again, turning on the lights when someone enters the room is a very common use case: so it should be doable Your research. But again, turning on the lights when someone enters the room is a very common use case, so it should be doable.
I am quadriparetic and use a wheelchair. We use a lot of motion activated lighting at our house because I can’t work regular wall switches. We acquired a number of different brands over the years And as long as the sensor is positioned appropriately, the lag is never more than about two seconds and for some brands noticeably less.
Anyway, to go back to your original question, the GE motion sensor switches that work with smartthings should not typically be triggered by a ceiling fan. The sensor is positioned below the switch and the detection zone is not that high. It doesn’t have configurable zones, but it is designed to solve the typical use case of turning on the lights when someone walks into the room.
I believe it will require custom code: