Longest distance motion sensor


(Jack R) #1

Setting up my security system around Smartthings. Which zWave motion sensor has the farthest detection area? Thanks


#2

There are two significant distance measurements for this type of Z wave sensor.

The first is the detection area which is the distance from the sensor that heat changes can be detected. (Although these are called “motion sensors” the PIR sensors (passive infrared) actually detect small changes in heat passing over the sensor. This is why they cannot detect through glass, for example.)

The second is the range, which is the distance that the sensor can be placed from the next Z wave repeater in the network. For this, all Zwave plus sensors will be about the same, and will be the farthest range. Older Zwave generations have a much shorter range. Note the battery powered devices do not repeat. Only mains power devices do, typically light switches, in wall receptacles, pocket sockets, relays, or Z wave (not zigbee in this case since zwave repeats only for Z wave and zigbee repeats only for Zigbee) lightbulbs.

There is also a third measurement, network depth, which is the maximum possible distance from the hub. With any Z wave, including zwave plus, this is limited to four hops from the hub. So the maximum possible distance from the hub with clear line of sight using only the Zwave plus devices would be 4 X 150 m, about 3 times classic Zwave.

For both range and network depth, note that there is a very significant difference between the theoretical “clear line of sight” maximum and what you usually get. Many things can reduce signal strength to varying degrees , including brick, cement, metal, wood, rain, etc. Indoors we usually plan for about 40 feet for a classic Z wave device, and 75 to 100 for zwave plus. But there’s a lot of variation depending on local architecture.

We should also note that most Z wave motion sensors don’t work well outdoors at all, and their manufacturers usually recommend against their use outdoors. You just get too many false alerts from this type of technology. Because they’re actually sensing heat differential, just a cloud going across the sun may cause enough of a difference to trigger the sensor. For example even though the Aeon multisensor is rated for outdoor use, the manufacturer recommends disabling motion sensor so that the light and temperature sensor features can be used outdoors.

The original question

So back to your question. If you are asking about the detection area, the Fibaro multisensor is probably the best at about 7 m.

Most of the other sensors have a detection area of around 5 m.

On the other hand, the first generation of the Fibaro was Zwave, not Zwave plus. So its range was significantly shorter then the Zwave plus devices like the newest Aeon. However, The Fibaro has a new generation due out this month and I think it will be a Z wave plus, but I’m not sure. If it is, it will probably be the best for detection area and equal to the other Z wave plus sensors for range.

and the other issue

All of that said, I personally don’t use SmartThings for any security use cases that involve life or death issues. It’s just not reliable enough for me. I use it for non-critical alerts like a reminder that the guestroom window was left open when rain is expected, but I pay for a separate security system for the critical stuff. If you search the forms you will find much discussion of this issue. It all comes down to your personal requirements for peace of mind.


(Jack R) #3

WOW ! What great information. Thanks. I agree on your thoughts about life protecting security systems. Honestly I just need something to trigger an alarm when on vacation. When I’m home I have the best system in the world to protect my family. Two big German Shepherds.