No, this is not a "light!" (short double-pulse every hour)

So Sense found a new mystery device (device 3) and the community thinks it is most likely a “light”. No way!

I wonder if this pattern looks familiar to anyone here…

  • Peak power is exactly 38W (but off most of the time)
  • Each instance is a pair of short pulses about a minute apart. First one slightly longer than the second one.
  • Each pair is exactly 1 hour apart, (but there are sometimes long gaps or missing hours).
  • Occurs 24/7, even when everybody is asleep.
  • Historically, the first sighting is mid January. Don’t remember if I got a new device.

Here are some screenshots.

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Can I start off by saying that a lot of halogen flood lights are 38 watts… :slight_smile:

What’s the duration? It looks like about 10 secs. I’m pretty crazy trying to track down mystery wattage, so I would be sitting at the breaker box throwing breakers every hour, while my family sits in a dark/quiet house, until I see the Sense meter drop 38 watts.


You might want to take a look through the device library here. I have filtered to only look at detected devices with usage between 0 and 50W.

If you have a small flood light turning on for a few seconds every hour, I feel sorry for your neighbors

This is exactly why I bought a KP125 smart plug. It’s helped me track down a couple of these mystery devices. Two that i can recall were components of refrigerators or freezers.

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It definitely not any floodlight and it is definitely not isolated to night-time. Our only outdoor lights are 2 ~3W LEDs that are always on at night.

Obviously, it is something on a strict timer (i.e. has some brains in it!) and 38W are definitely more than any typical electronic gadgets use (most are on TP-link sensors anyway). Why would it wake up every hour for a few seconds twice, 1 minute apart? And what is it doing?

I’ll do more research…

So looking at the quoted device library, we do have a Dyson charger so this 38W thing looks quite similar (ours is a V11, though). I’ll put in on a Kasa plug.

And at some point I just started ignoring these mystery devices. Most are less than 0.2% ($0.05) of my monthly total… not worth my time.

Indeed. Dyson charger would be my guess.

@kevin1’s recent list of Likely/Unlikely detections:

Makes me think we should have a list of devices by max/average wattage and some kind of timing behavior. Analog/digital implications; AC/DC. A rough categorization of devices without getting too drilled down into the details.

We have a Dyson V8 and don’t see anything like that, but the charging certainly could be different from device to device. I would just unplug it for a couple days and see if it goes away.

Good luck…


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It might be fruitful to compare the various (popular) Dyson models and chargers if anybody has smart plug waveforms to post we can add them here in the Device Library or create new entries for the different models.

I guess these double-blips probably occur once the battery is fully charged, but left connected. I would not know the pattern during charging. Might be more complicated. Will do some testing.