Observations after combining 2x200A to 1x400A

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.

Donn

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.

Thanks

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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Don’t get me wrong I’m willing to try it out, just seems there are easier alternatives, that does not require a new Sense device with three CT ports.

I’m still interested in hearing from LA area SCE customers that are running CT clamps on the 400A side?

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I connected the current clamps to the 400A circuit today.
Will the sense start learning by itself, or do I need to contact support and ask for help after swapping from 200A to 400A?

I can’t tell from your explanation whether you have already done it, but you probably need to get out of 2x200A mode and run setup again for using only a single pair of CTs, to go through the usually calibration and signal check. Once things are setup in the new config, I’m guessing that Sense will start learning again. If Sense detections are sensitive to which pair of 2x200A CTs they were found under, similar to how Sense differentiates detection on L1 vs L2, then many of your previous detections will have to be re-learned for the single pair CTs.

To be clearer, I drilled a hole and installed a rubber grommet between the service and user sides of the panel, powered the sense down, moved the CT’s from the 200A leg to the 400A supply side, and powered back on.

The reported usage was excessively high, seemed something was wrong, I cycled breakers one-by-one (in both 200A panels), and observed no drop in usage. When I cycled the solar feed breaker, the sense stopped reporting, as if it reset. I power cycled the sense, it came back online, and reported very low usage.

I decided to do a data reset, did the solar off-on dance, and solar started reporting, but usage stayed at 0. When I look at the device details I can see usage is -700W, assuming solar is feeding the grid, but the dashboard reports 0W usage and 3KW solar generation.

Something is funky, I contacted support and asked for help.

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@pieter, did you ever get this resolved?

I have a similar issue 400a single with solar. When I attempted to do my startup, my sense also stopped reporting consumption when I killed the solar. I suspected that the main and solar CTs were reversed (connected to the wrong ports) and asked the electrician to come back out to reconfirm everything. But if there is another issue, it would be nice to know before he comes back. Thanks.

Yes, I reported the issue to support, they corrected whatever was wrong on their side.

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So, I got my initial issue resolved. Turns out there was a phase error with my two inverters due to a wiring issue. Easily addressed by the electrician.

Following the resolution of that issue, I did a data reset and went through the startup procedure again. In the Monitor page, I now see exactly what I would expect:

Mains -2866 W -2899 W
Solar 4977 W 4967 W

However on the Now and Meter pages I see

<solar_symbol> 9945 <plug_symbol> 0

The mains number should be -5765 rather than 0, correct?