FAQ: Ghosts in the machine — zwave lights randomly switching on and off (October 2021)

I am totally boggled. I’ve tried reading here in the forums and can’t find a solution. It’s insane to me that I can’t even see the commands that are somehow floating through my system and causing this.

I’ve had ST for probably 6 years now in the current house. Some time after there was a software upgrade to the major new ST, I would start having certain lights randomly turn on and off. There are like 3 or 4 lights, maybe more, that are doing this. Different types of devices (GE wall switches; certain outdoor switches). We’ll be sitting there in the evening and the lights will cycle off, then on, then off, then on, then off, about a second between each. Multiple times each evening I have to manually re run my sunset routine to get all the lights back on to where they should be. It happens a couple of times usually in the evening, another light in the kitchen also seems to do this in the morning. It seems it’s always around the same time but never the exact same time.

What’s the deal with this? Am I the only one having these issues? It’s insane.

I’m so tired of trying to debug it — will just buying a new ST Hub solve this for good? Though I really don’t want to have to reinstall my whole system, I’ve got 50-60 devices in total.

Is there no way to figure out where these commands are coming from? Can’t I watch comments being sent over the network and figure out what is triggering them??

Thanks for any help!


Maybe you have one of this running

No, I don’t have this enabled (I see it available in the Labs tab, I haven’t used it). But thanks for the suggestion!

Are you running either a Google or Alexa device(s)? There is at least one other post in here where Alexa was doing that. @JDRoberts will know what I’m referring to.


Interesting. I have probably 5-7 Amazon Alexa devices spread around the house. We have those integrated with ST so that I basically can say things like “Alexa, turn off the Den lights.”

Is the issue that the Alexa is sending random commands to my ST??

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Holy crap, it looks like Alexa may be it. Amazon has some “hunches” functionality that apparently is sending commands to my devices. For all the same devices that keep having this issue, in the Alex app I see things like “Yesterday 9:11pm Alexa turned off Outside Front Lights Switch. Alexa had a hunch that no one was home and the light is usually off when you are away. Did Alex do this right? YES NO”


I have now turned off (I think) Alexa’s “hunches.” I’m hoping this works. Thanks a million @Bry , this has been driving me absolutely bananas… Amazon really is trying to take over our lives, probably what I get for inviting so many of their devices into my home…


Yep, that’s what I was thinking of!


Buying a new hub probably won’t help. This type of issue (usually called “poltergeists” in the forum) is almost always caused by one of three things: circuit load, an automation, or a cloud glitch.

  1. most of these switches have an overload feature where sudden surges on the circuit Will cause them to turn themselves off briefly, then turn on again, and repeat if the surges repeat. Hairdryers are a classic for causing this, but so can some older vacuum cleaners, power tools, space heaters, anything which causes a sudden high jump in search on a shared circuit. Evenings are typically the worst because everybody is home and there are lots of devices in use.

Because this is a mechanical issue, there won’t be anything in the system logs or notifications to show it happening. :thinking:

It’s usually pretty easy to find with detective work, though. I have everyone keep everything turned off except essential lights and appliances like refrigerators. Then start turning on the things that normally get used at night one at a time. Then adding multiples, starting with the most likely culprits. Once you find it, you can probably make the problem happen every time.

The fix is either behavioral: don’t use everything all at once or electrical, bring in an electrician to evaluate the current situation and if necessary add an additional circuit.

Our house was built in 1955 and we had this problem when we first moved in. No smart equipment at that time, but lots of other stuff including blenders and hairdryers. and a space heater.

Over time we ended up adding three new circuits and now we don’t have any of those issues.

  1. automations. The one that @bry is referring to is that Alexa can create “hunches” which guess what you want to do and then offer to set it up as a regular routine. The offer is made verbally and it’s way too easy to say yes to, in my opinion. These don’t show up in the regular routines section of the Alexa app, but they are in there, so you can check to see if any were created unintentionally.


I don’t know whether Google has a similar feature or not.

Another automation possibility is a presence based automation based on a phone, and you are turning the phone on and off causing the system to think that you are leaving the house and coming home again. But most people figure that went out pretty quickly. :thinking:

The easiest way to diagnose The automation issue for zwave switches is to disconnect the hub from power for a night. ( also take out any batteries if it’s a V2) if the lights still go on and off, it’s not likely to be an automation.

(There’s a small possibility that it’s zwave direct association. We had a dog who used to steal remotes and chew on them, which could cause a lot of random poltergeist activity! :ghost: but from what you described, I don’t think that’s likely unless you have a single remote that controls all of those switches.)

  1. cloud glitches. These can happen, although they aren’t usually repeated multiple times. The most common issue is an automation being delayed and then running several hours later. But sometimes they can just apparently come out of nowhere. If this only happened one night I would think that might be possible, but if it’s happening every night, I think it’s more likely to be 1) or 2) Still, report the problem to support if you can’t find anything else as they can see some things from their side that we can’t.

Good luck, I know these are very frustrating. :rage:

  1. One other possibility I will mention, although the first three are much more likely, is drone activity. Some drones do operate in the same band as zwave, and one flying near your house can cause drop off issues for your own equipment. But if it’s that, it will be many different kinds of Z wave devices, not just light switches. And quite commonly it will start on one side of the house and then be the other side of the house. This is a real issue, and we have had a couple of community members affected by it, but it’s still pretty rare. So it would mean that either you have a neighbor with a drone or you have a city government with a drone and they are flying near you. (Or in one case, a community member had an issue with his own drone that he brought in the house to recharge.) But see if you can eliminate all of the other possibilities first, and then we can talk about this one. :rocket:
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Thanks @JDRoberts. Very helpful.

Regarding your point here:

" 2. automations. The one that @milandjurovic71 is referring to is that Alexa can create “hunches” which guess what you want to do and then offer to set it up as a regular routine. The offer is made verbally and it’s way too easy to say yes too, in my opinion. These don’t show up in the regular routines section of the Alexa app, but they are in there, so you can check to see if any were created unintentionally."

The crazy thing is that my Alexa says NOTHING when these have been triggering. It doesn’t give me a heads up, doesn’t ask if it should do it. It has just been doing this. Apparently the flicker on and off is my cue to know Alexa is doing this, and I can say something like “Alexa stop” or “Alexa cancel” during that flicker period, at which point it will then discontinue the hunch and leave the lights on. But heck, I had no reason to know it was alexa doing this. In any event, I’ve disabled hunches now, so, hopefully, this will be solved. Will report back.

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Once the hunch is created, it runs automatically in the background, as you noted. Basically it’s a special kind of routine that Alexa is creating for you based on activities that you perform frequently. They can be helpful, I just think the set up process is too easy to do by mistake. Alexa will just say something like “would you like me to create a routine that turns your lights on?“ If you don’t say no, it’s off to the races!

The fact that these don’t show up in the regular routine section is also annoying to me, although I don’t know if it bothers anyone else. you have to drill down into the hunches area to find them.

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I’ve had Google send a notification to my phone asking if it should automatically run a routine (as in a Google Assistant routine) that it noticed I ran at a similar time each night. But it never asked verbally over the Google home, and it didn’t do it unless I accepted on the notification.

I never accepted one of the prompts so I’m not sure where they would have ended up in Google land.

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Just to close this out — zero issues with this after turning off Amazon’s “hunches.” Good riddance!
Thanks again all.