Dedicated circuit shows more power draw than entire house

I’m seeing odd behavior here. I have my flex sensors set to monitor power draw from my EV and water heater, both of which are in dedicated circuits. As you can see in the attached screenshot, sometimes the car appears to show a higher wattage than the combined total of everything in the house. Not sure if there’s something I did wrong with the installation or something else.

Any ideas?

Flex Sensors should give you an accurate read as long as you got the setup right. Is your charger 120V or 240V? Does the 3kW charging power seem correct ?

That is odd.
It’s unusual for the CT’s themselves to be off especially by that much so it’s quite likely an installation issue.
Could post a picture of how you have them installed?
You don’t happen to have a solar system do you?

He is using the solar CT’s to measure the energy to his EV.
3000 watt is correct for certain Volts. They were limited by the onboard charger.

What I think is happening is what with solar is know as supply side vs load side hookup.
The Sense monitor in one case adds the extra (solar/dedicated) CT reading to the grid CT reading or in the other case subtracts it from the grid CT’s.

Among people with solar (my self and some of my customers I installed Sense with) all had the experience that “suddenly” the settings had switched after initially detecting it right.
If this also happens with people who do not have solar and use the extra CT’s for measuring dedicated appliances, that is bad, really bad.
I would sit down with whoever wrote that detection algorithm and have it redone from the ground up because this appears to be beyond clumsy.


I’ll try to post a picture of the layout later. I do have solar, but the solar is joined with the mains before it comes into my main service in this box. 3k is about right for the volt, it’s 240.

@charles, thanks for confirming the 240V. Sounds like you set your Flex CTs correctly - for single CT measurements of 240V load.

If you are using the second port for the DCM (direct current monitoring) of the EV and water heater, and have solar, Sense is not measuring your solar production. That would mean that Sense is only seeing and reporting your net usage (Total Usage - Solar Production = the 2,587W in the lower left corner). If that screenshot was snapped during the daytime, then you could easily have net usage lower than the usage of your EV.

I don’t think it’s the solar: my main reason is that my solar is joined to main power -before- it comes into my circuit breaker. Unless I’m misunderstanding how this works. My inverter feeds to a box outside the house where it’s joined to the main service, then that feeds into the box. At least that’s the way the cables seem to be run. The inverter definitely does not go straight into the circuit breaker, and there are only the three cables into the box.

However, when I was taking the photos I noticed that I hadn’t locked the CTs. Could that have caused the main sensors to fail to read correctly?

Photos attached. Note that my house is 140 years old, so there are generations of wiring leading into this box (thankfully the knob and tube was all torn out sometime before I bought the place). It’s not pretty. The box itself was installed in 2018 – I had it installed when my solar went in.

You’re correct - if your solar feed-in is upstream (toward the grid) from your mains CTs, your mains CTs are seeing the full draw of your house load (your solar and grid are both flowing through those CTs). Since that’s the case, I would fall back to the Not-completely-closed CTs as the most likely cause.

You might want to look at your Settings>My Home>Monitor>Signals section to see how the power is being dished out on a per leg basis - when your car is charging and little else is happening, the two numbers should be pretty balanced.

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I wanted to wait a couple days before I could say it’s confirmed fixed. Even though the CTs appeared fully closed, not having them locked appears to have been the problem. Since my original post, I’ve been checking repeatedly and the water heater and EV are always under total consumption.

It seems that all the data collected since I installed (September 5 or so) may be off. Now I’m trying to decide: do I start over clean? Do a factory reset and start over?

Thanks for the help on solving this!

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I wouldn’t do a factory reset. Not worth going through setup and signal check again in my mind. You could consider a data reset, but I’m not sure anything is harmed by having a little questionable data at the start. Things like Always On and detection will readjust to the new normal.