Device 1 from Outer Space

I’m only a couple of weeks thus far with Sense and I love it. One thing that does have me scratching my head is the “Device 1” wattage plot. Sense “recognized” it a couple of days ago and then plotted its history back to the installation date/time:

“Device 1” pulls 65W - 75W after an initial 45W turn-on and does it 24/7 as shown with little variation. Here’s the kicker - I’m having so much trouble tracking it down (I unplugged our 3 refrigerators first) that I decided to unplug the whole house! And like Frankenstein it wouldn’t die! Its power meter kept plotting the 65W - 75W plateau after all breakers were shut off.

My home has an outdoor main panel fed directly from the power company’s metered service entrance. Indoors there are two sub panels; downstairs and upstairs. The main panel is where I shut off both sub panel breakers as well as the few others remaining that power things like our well pump.

The only thing left ON was the breaker dedicated to the Sense Monitor (nothing shared).

Then I used a multimeter to verify that the output of each OFF breaker actually read zero volts. They did.

The only thing I can think of for this mysterious “Device 1” is:

  1. The Sense Monitor itself is using this power, but I doubt it.
  2. The Sense Monitor is in error.
  3. The Sense Monitor has discovered an alien armada preparing to attack!

Ideas? TIA.

@lholland, watching the bubbles and the Device Power Meter, when flipping breakers can be a little deceptive. If you have your mystery device on and you flip the breaker off, there’s a pretty good chance the bubble will stay up and the the device waveform will keep going in the Device Power Meter. That’s because Sense is looking for that specific device’s off-signature rather than a “breaker off” to tell it that the device has turned off. Again, don’t rely on the power bubbles or the device-specific Power Meter to tell you when Sense has stopped detecting the device if you are turning it off in a different way than normal.

What you really need to do, is to catch the device when it is is on while the rest of the house is quiet (electrically speaking), then flip breakers off while watching the regular main Power Meter. If you see a a corresponding 75W dip in the main power meter when you flip a breaker, that’s likely to be your culprit.


Very helpful - thanks Kevin. I’ll report back when the alien is located. :))

in case its not a Sense Alien… any chance you have a car/lawnmower/motorcycle on trickle charge/battery minder.


Found it!

After Ben’s reply I was rooting for my lithium car battery charger/maintainer because it sends pulses during the maintenance phase of a fully charged battery. It’s something I got for a toy car that I don’t drive as much as needed to keep the battery happy.

Nevertheless, it turned out to be our small Samsung refrigerator with a “digital inverter compressor”, whatever that is. Probably reverse engineered Area 51 tech.

Kevin’s comment about the non-real-time nature of the bubbles and Device specific power meters was key. Unplug stuff and be patient. It does appear that the system-wide power meter plot responds in real-time, or close to it.



I never would have imagined that a Samsung appliance would be the medium responsible for first contact. Great work, @lholland. I think there’s some potential for further communication if you can use the ice machine to send messages in morse code.