Looking for a sensor that recognizes colors, or electricity supply

Hi there - long time lurker, first time poster.

I’ve looked around and haven’t found what I’m looking for, hence the question here.

I have two power supplies coming to my house: the regular electricity and a third-party generator (due to the freq electricity cuts in my country). In the power box, we have installed two lights, one red and one green, so we can tell by looking at them which source is coming through. Regular electricity gives us 30Amp total and is metered, generator gives us 10Amp total and is unmetered. So it’s important for us to know which power is coming through.

I’d like to add a sensor to my ST that would let me know somehow which power source is working now. Either a light sensor I can stick facing the box that would recognize the difference between red and green, either something we can install in the power box that would know if/which power it’s being fed.

Just to make things worse, I have an ST2 hub (US ZWave), but I live in a country with 220V power supply. Battery-powered sensors are obviously a better solution, but I’ve come across stuff that works on 220V with US Zwave.

Any ideas?

If you have 2 distinct power sources, then perhaps the 2 distinct clamps of a HEM (Home Energy Meter) could sense which is active.

Model 1 (discontinued) of this were being sold pretty cheaply, but I guess the new model isn’t that bad of a deal:

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Why not two cheap smart bulbs. If bulb 1 is online it is box 1 that is working. if bulb 2 is online it is box 2

If there is no power to the bulb it will be offline.


Are there any safety issues if SmartThings reports incorrectly, in particular if it fails to update when a switchover occurs? Or is it just a financial matter?

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I am assuming, based on OP that they want to be notified if they are on generator power because of electric company power was out due to outage or not.

I know, but will there be a safety issue if the SmartThings app indicates that 30 A are available when in fact it has switched over to the local generator. That is, will people take the incorrect information and make an unsafe choice because of it.


That’s a great suggestion, but looks like it’s powered by electricity. So US gets 110V and US Zwave, EU gets 220V and EU Zwave. With 220V and the US SmartThings Hub, I have no dice. I’ll keep it in mind if I switch over to a UK ST hub at some point.

Hmmm, the two lights are teeny tiny LEDs. I’m not sure if I can find ones that are smart, but I like the way you’re thinking. I might be able to use a switch in the wire that’s going to the light to know if it’s on or off. Thanks!

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@Gopack2 @JDRoberts nope, no safety issues there from false reporting. We use it mostly for two reasons:

  1. to know if we can take the lift instead of the stairs: lift is on the proper electricity line but not the generator, so I may delay arriving home if I know I can’t take the lift now and suspect that the electricity will be available soon
  2. to use various demanding appliances if it’s the proper electricity source. Again, no safety issue there, we have a switch that turns off the generator power if it overloads over 10A, and some appliances (washer/dryer) can’t even use the generator because we isolated them so even if we flip them on, they wouldn’t turn on unless on proper electricity.
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You could use smart plugs the same way as a light bulb. Put 1 on the circuit for main electricity and another one on a circuit tgat is only powered by the generator. Then the same wAy if online that circuit is active. If off Olin’s tgat circuit is out.

Just a different option same results.

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The sensing clamps do not care what the voltage is. They do not directly use current; they just measure it.

The input power is optional (batteries can be used), is just a 5v mini-plug DC power supply, so it can be powered by “any” USB power supply, many of which are auto-switching to 220v.


Awesome, thanks for the clarification. I’ll look into it, seems like the best solution so far.