40 Amp AC & 90 Amp Main breakers in meter panel on outside of house (at meter)

I am not sure how to or if I can monitor my home HVAC energy usage.

The outside breaker box that is part of my Meter Panel has:

  1. a 90 amp breaker that feeds the Sub Panel in the garage with all the individual house circuit breakers -AND-
  2. a 40 amp breaker that feeds the HVAC.
    In the attached picture of my Main breaker box, the blue tags are on the two clamps over the ‘street power’ wires coming from the meter (left of breakers). The orange tags are on the two clamps (for Solar monitoring) over the wires that come out of the 90 amp main breaker that feeds the subpanel in the garage as well as receives power from the Solar panels. Both sets of clamps have the label sides facing the direction that the power comes from.

The problem is that by design, the AC 40 amp breaker is fed from the ‘street power’ wires coming from the Meter, just like the 90 amp Main breaker.

a) To allow the Sense Monitor to see and monitor the power flowing to the HVAC, would it work if, in addition to the wires from the 90 amp main breaker being inside the ‘Solar Clamps’, that I also ran the wires coming out of 40 amp HVAC breakers through those ‘Solar Clamps’? I’d be sure to match wires from the same sides of their respective breakers (in case that matters). It would be pretty bad if the largest energy user, the HVAC’s energy use, was not able to be seen and monitored by the Sense Unit and app. My house was built in 1982 in Northern CA. While not the norm by far, hard to imagine this set up is that unique.

b) I think I read it is not to code, but also that it should not matter, that I connected the red and black Sense Unit’s red and black power wires to the 40 amp HVAC breaker because there is no place to add a smaller breaker. Other than an inspector maybe not liking it, does it cause any risk to the Sense Unit? If coming off a 40 amp breaker is potentially ANY risk to the Sense Unit, I could easliy install a 10 amp inline breaker on the red and black power wires.

Thanks for any insights. :smile:
PS. I am a few months new to Solar and just installed Sense last week. Barely slipped under the wire to be in NEM 2. Glad for that.

Do a “search” on this forum. Enter ‘wired the HVAC directly’ for your search string. I discussed my experience in a detailed blog. It’s too long to re-type. Hope that can help you.


@davekro , here’s the link to @Dcdyer ’s posting.


Thank you Kevin1 & Dcdyer, I went to the link. Lots of great info!
Dcdyer, my setup matches the diagram you posted (copied here).

I got excited for a second that I could easily move the CT clamps to the inlet wires coming from the street to the meter. But, correct me if I am wrong, the incoming CT clamps for street power readings (w/ blue tags on left of brkrs) currently on the street side of the buss bar that supplies both the 90A Main & 40A AC brkrs. would read exactly the same if moved to ‘before the Meter’.

So it seems my concern of the current going into and thru the 40A HVAC breaker was not ‘seen’ by the street side CT’s, was wrong. I may move the street side CT’s into the bottom of the Meter panel, so they are not crammed in like they are now. Currently, it’s very hard to verify the clamps are completely closed, but I believe they are. It seems that with the street side CT’s where they are -or- moved to before the meter, it matters not that the HVAC breaker is where it is, or if it was actually in the sub panel (in the garage). Let me know if I am missing anything here.

The Solar supply side CT’s (w/ orange tags) are currently on the wires that are a loop out the top of the main panel. I’m guessing these are From/To the subpanel between Enphase box and Main/Meter box, w/ only the 30A Solar disconnect brkr and a second 90A (garage subpanel) brkr. Sould those Solar CT’s be on the wires directly ‘out of’ the (first) 90A Main brkr.? Both Solar CT 's labels face toward the solar supply.

Confusing? Yes to me too. ;o)

Dcdyer, HVAC wired direct to Meter

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To: @davekro

I found when my CT clamps were at a 90 degree angle to the incoming wires and perfectly centered, I got a closer reading to my power company’s meter. I did a full statistical analysis which I posted in the forum. If you feel comfortable doing the work, then moving your CT clamps to a less congested area might give you a better reading. I would recommend that you tape the CT clamps closed. I used masking tape.

You should consider making a line diagram for your own documentation. It will help you and the Sense support team if you have any future problems.

If you use the ‘@’ symbol before a user name in the forum posts, then that user will receive an email notification.

Good luck with your installation.

@Dcdyer ,
Thanks for the info on best if possible to have CT’s at 90º to wire. I will definitely pull the utility power CT’s from their ‘crammed in’ location to below the meter with clean, easy access. I will do my best to tape the CT’s so they can hopefully remain square to the wire and centered. I’ll probably find some foam or something near the O.D. of the #2/0 wire and the I.D. of the CT’s and tape that around the CT’s and their wires. Who cares what it looks like, if it gets more accurate readings. ;o) Thanks for the Tip.
PS. did the @ sign work? I put a space after your user name before the comma in case “@Dcdyer,” might not be recognized with a comma at the end. ;o)


The @ sign should have worked - when the usename turns to grey in the post, that’s a sign that Discourse (the forum system in use) picked up the username. You can also use the @ sign when searching the forum for postings from a specific user, along with other search terms.

ps: Hi from the other side of the Bay - Menlo Park

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Wil temporarillly diconnecting a pair of CT’s from the Sense unit cause any problems, or simply not receive any data for a bit and fine after reconnection? Does it restart or loose any historical data or device info/names I have entered or ‘unfind’ the devices it has already found?
I’ll need to unplug the utility side set of CT’s from the Sense unit in order to move the CT’s into the meter box next to the main brkr. box where they are crammed into now. Then I can orient the CT’s at 90º to the cables and center the cable in the clamps.


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Hello Kevin from the south peninsula from Discovery Bay. :smile:

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To: @davekro
If you can identify the incoming service cables before your meter and after, then it would be better if you kept the same CT on the same cable. You will need to leave the black/red voltage wires on the same breaker you are already using. I used red electrical tape to identify my second hot leg cable at all locations inside my breaker panel.

Yes, you will lose some data while you are transferring the CT clamps. If you do not get them back on the same conductor cable, then you might have to go thru the initial setup again.

I used pipe foam insulation which I trimmed down for my CT spacer.

Good luck and be safe.

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"If you can identify the incoming service cables before your meter and after, then it would be better if you kept the same CT on the same cable. You will need to leave the black/red voltage wires on the same breaker you are already using. "
It seems like you are saying to keep the CT clamps on the same side (Lft/ Rt), same phase as they are ‘post’ Meter/ ‘pre’ Main Breaker when I move them to their new ‘Pre’ Meter location. I was planing on that. Thanks for the black foam pipe insulation recommendation, I have many sizes of that! ;o)

“Yes, you will lose some data while you are transferring the CT clamps. If you do not get them back on the same conductor cable, then you might have to go thru the initial setup again.” “Some Data”? Not sure how much or what data is at risk, but not a big deal since Sense has only been connected a few weeks and only recognized a few Devices so far. I will get them back on the same cable orientation. I actually wondered if I would need to go through the initial set up again, because even at night, it shows I’m producing Solar ≈2,000 w/ (Orange bubble) and the only other bubble is the Gray one showing “Other” ≈4,000W. I wonder why I do not see bubbles for already recognized Devices? Like I set the Microwave (recognized and Brand/model info entered) to run 90 secs, but the computer (browser) and Android phone App did not show a bubble for it -or- show On or Off in the Devices list under Microwave. Makes me think Sense App is not running properly, yet.

Thanks for your info!

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If your microwave uses inverter technology, then SENSE will not find the device. Most of my devices took 6 weeks before SENSE identified them. I installed my monitor 6 years ago.

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A matching screenshot of your Settings > System > Signals section might be helpful in diagnosing whether things stayed configured correctly after CT changes. Shows power(s) and voltage for each leg.

Two things…

Thank you for letting me know about using the @ sign to let users know they are being mentioned. But I have no feel or experience with using that to know if people like to be notified every time they are referred to by name, or if that’s like getting way to many ‘notifications’ that might feel like spam. In practice, is it preferable to only occasionally @name somebody, if you want to be sure they see something. A message like this would not fall into that category. I don’t want to be annoying people… IF I DID I’D JUST YELL AT THEM IN ALL CAPS. ;o)

My microwave does not have inverter technology. I guess that means that Sense will record on/off, on/off repeatedly when cooking is at less than 100% power?

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I attached a picture of my phone because my Samsung said “it would not ‘screenshot’ for security reasons.” That’s the first time I ever ran into that.

Before I yesterday when I: removed my CT’s, rearranged the heavy cables to make more room, unplugged the Utility CT plug from the Sense box, -THEN- inadvertently unpowered the orange box by pulling out the red and white (ground) power wires to the orange box… Dohh!

Anyway, before yesterday’s exploits, I would see the Solar and Other bubbles only.

Just before I took the screen shot shown here (Solar 1008W, Light 2 294W, Other 67W, ONLY the Solar bubble showed! All ‘Other’ was surely using way more than 67W at the time of Scrn Sht.

I removed the CT’s to move the wires to make more room, move the Utility supply CT’s to below (before) the meter, and mark up the CT’s with colored Sharpies (OCD ;o). I paid close attention to keeping the two Solar CT’s on the same Black wire/left, Red wire/right orientation because that is what brought the Sharpies out. ;o) But when I got over to the Utility supply CT’s I “think” they are oriented the same, but I am not positive, in case that would account for any of what you see in my pictures or description.

The OEM labels on the CT clamps are for sure towards the direction of the Utility and Solar power ‘supply’ respectively.

I have been solely viewing the Sense data via the browser, not the phone. I see the phone has much more data.

Another goof on my part, I turned off the breaker by mistake just now that powers the Sense box. But when flicked back on, NOW the “Other” Bubble is fluctuating around 1700W, and Solar at +/- 825 W. But the Sun is down, sunset about 10 mins ago, it’s dusk. Enphase says my system is producing zero watts as of 5:00pm. Sense at 5:03pm says Solar is flowing 840W, and Other if flowing (consuming) ≈ 1700W. Solar has always read WAY high, day or night.

I am not positive the Solar CT’s are in the correct place, but I can’t think where else they should go. In this picture of my main breaker, the upper 40 amp breaker supplies the HVAC, the lower 90amp breaker, which before Solar was installed “Used To” supply the subpanel in my garage. Now the output from this Main 90amp brkr. goes out of this Main box up and over via conduit to a subpanel between the pictured Main box and the Envoy/Enphase Solar box. In this ‘Mid box’ the cables from the bottom of the 90amp brkr in the Main box go to the lugs on a 90amp breaker. power from the Utility goes “into” that 90 amp mid subpanel breaker, through that box’s bus bar’s main lugs, reversing BACK thru the conduit to be joined the the original wires that go into the wall of the house and to the Garage subpanel to supply energy to all hose circuits (except HVAC).

So currently, you are seeing the “Solar” Ct’s (blue) on the wires coming From the mid subpanel on their way to looping up into the wall where the power goes to the Garage subpanel. I hope this makes sense.

OK @davekro ,
Three quick thoughts…

  1. Good job getting the picture of the Signals section. The newest Android version of the app doesn’t allow you to screenshot or some reason. That’s the place you should be looking at to sort through what’s happening with the CT configuration. Your config is definitely wrong - you shouldn’t see any negatives. Your two solar feed-in should be somewhat close together in power when the sun is shining and near zero at night (maybe slightly negative -3W). Here’s a view of mine.

  1. You can find the Signals section in the web app as well. There are a few additional features in the phone app vs. the web app, but the Signals section isn’t one of those - it’s buried in the Settings as well. Here’s a helpful guide to the differences between the phone app and the web app.
  1. Unless you want to try a lot of CT flipping experiments looking at the results on the Signals section, I would contact Sense support (support@sense.com). They have the tools to rebuild your Sense configuration for correct operation.

I’ll need to check with Sense support later when I have time. Hopefully I will be able to send them some pictures of my Main, Mid subpanel, and Envoy/Enphase box. If they say I need to attach the Solar CT’s inside the Mid subpanel, I’m out of luck because it is 8.5 feet from the main panel. Thank you for the info.

You can get extensions for the CTs.