Observations after combining 2x200A to 1x400A

My house has a 400A electrical service divided into 2x200A panels. I purchased two Sense devices about 2 years ago and installed one into each panel. Both worked fine but I had to live with the inconvenience of having to set up separate accounts for each device. When the Flex cable was recently announced to allow monitoring of two separate 200A panels by one Sense unit, I immediately purchased one and installed it a few weeks ago.

As was warned about in the Flex cable install guide, I lost all the devices that had been detected by the Sense unit that was removed (devices identified by the other Sense unit that remains and now monitors both panels were unaffected). No new devices have been discovered since the Flex install including no re-identification of previously found devices. What’s more, devices that were identified quickly previously have yet to be picked up. The new setup has been in place about 3 weeks.

I realize that the Flex cable install guide warns that Sense won’t guarantee that previously identified devices will be picked up again after they’ve been lost. Has anyone else run into this issue? I wonder if the device needs further updates before detection on the panel monitored by the Flex cable matches that monitored by the original cable.

I have a slightly different 400A situation. I installed a Sense on my 400A mains with the middle port attached to solar back in April 2019. It has picked up 58 devices of which 28 are native detections. Others are smartplugs.

I installed a second Sense in May 2020, on a new separate account, in the 2x200 configuration, with no solar CTs (so net metering only) to experiment with it and see what it would detect. So far I have 22 detections of which 17 are native (the remaining 5 are Hue lighting groups). So the 2x200 configuration can find new detections, not previously associated with that account, though I’m a long way from parity with my 1 1/4 year old setup.

Given this, I assume that the waveform world looks different between the two configurations, though I also have a the solar/no solar wildcard.

Interesting observations. At least supports the theory that different CT configurations change detection ability. Hopefully something to be addressed in the future

I’m having a similar issue. I’ve combined to the 400A with the flex clamps and I have no new devices detected. The old sensor detected things like my dryer very quickly. It’s been several weeks now and still nothing.

Hi same issue here. No new detections 3 weeks after combining two 200A units. Overall power usage seems correct. Wondering if I should do a reset.

I finally got a couple of detections of devices that had previously been identified (took about a month). It did occur after we lost power briefly in a storm so power cycling couldn’t hurt.

Still a long way off from the number of devices that had been identified before the changeover.

Thanks for reporting this.

@rsinglet2000, @rosenblumb, @donn1: are you ok with us looking at your data? Also, if you still have the other monitor, could you let me know the serial number from it (on the bottom of the monitor)?

Hi Ryan,

Yes, it’s ok to look at the data. I gave the other monitor to my dad in Wisconsin. He has since created an account and added it to his house. He said it is working and detecting. My account for that box was under [mod: email removed] e-mail if that helps.

I don’t have the serial number. Can I still log into my old account to get it?

Thanks for the help.


Fine with me to look at my data. Will message you the serial number of my disconnected unit directly. I also realize that I didn’t deregister the disconnected unit before I gave it to my neighbor to try - not sure if that has any effect at all. Thanks for looking into it!

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Hey Donn. Think you’d be able to get the serial from your dad? It can be found in the app: Settings > My Home > Sense Monitor. You can just PM me the number or a screenshot. That’ll be the easiest way for us to dig into the data.

Ignore this! We were able to get what we needed.

You’re welcome to look at mine as well. It finally found something on the second panel earlier this week. Wine fridge if that helps.

Did you have two Sense monitors prior to this, one on the second panel? That’s the only way we can really do any sort of comparison analysis. If so, can you just shoot me a PM with the serial number (or the email you had associated) with the monitor that was replaced?

Sorry, that one has already been given to a friend and he’s put it in his house. I assume you can’t pull the historical data at this point.

Yes I had two monitors previously. Will send you the email associated with the old one.


Actually, some higher-level data remains. If you have any info related to that monitor, we should be able to do some analysis.

Serial number sent.

Hi, I decided to not wait for 200A + 200A + solar support, so I just installed two Sense’s, one with solar, one without.

I see that some users are running the 200A CT’s around the 400A service line, I did not know this is possible. I should have joined the forum before I installed, lesson learned.

Has anybody installed on the 400A service using SCE in the Los Angeles Area?
How did you get SCE to open the panel and agree to the CT’s being installed?
How did you get the CT wires through to the service side, in my panel the sides are isolated, wnd will require drilling and a grommet?

It seems much easier if Sense were to supply 400A rated Rogowski Coil flexible current transformers. It is unfortunate choice for Sense to name the extra CT’s “Flex”, when they are clamps.
In my panel, and by the looks of other 400A panels, a flexible CT will easily wrap around the 200A + 200A feed, allowing for a user install, and not requiring the SCE to open the service side.

Hi Pieter - a couple of thoughts on CT sizing:

  1. It would be a rare home that pulls a balanced load of more than 48,000 watts (200A at 240V). I have a 400A service entrance mainly because the guy that built the house for himself was an electrician. I have yet to see long-term (several minutes) loads over 20kW.

  2. I once designed a measurement product that included a current transformer and found during prototyping that even the less expensive ones could generally handle brief loads of about 10 times their RMS rating and report the event accurately.

Understood, but:

  • Creating CT calibration profiles for different model CT’s is well a known art, even the most rudimentary open source projects support calibration profiles for various model CT’s.
  • Using a 200A rated CT on 400A service is simply out of spec, no matter what the exposure is, and could be a point of friction for utility provider approval.
  • Rogowski coils would be a good solution to measuring around 2 x 200A feeds, and even problematic bus bar setups.

My point being that the technology is not an issue, Sense could support a 400A rated clamp or Rogowski coil CT with a suitable calibration profile.
They don’t even have to sell them, the type of user that is willing to crack open a 400A non-user-serviceable panel is the same type of user that can wire a CT cable.

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My 2c - I have a Sense 200A CT on my 400A feed and another on my solar backfeed, and even when I am running the most demanding loads (maybe 160A at 220V), Sense stays within 1% of my PG&E revenue meter. But even with huge EV loads, I never get near 400A.

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