Wattage values don't seem to be correct


I have to following setup:
200A main panel called Main (Has CTs on the input side called Main_A, Main_B)
100A sub panel feeding off of the Main panel called Apt (CTs called Apt_A, Apt_B that are after the 100A breaker in the main panel)

The main CTs should always read a higher wattage as it is all the breakers (including the Apt sub panel.)
Challenge is that Apt_A+Apt_B reads higher than Main_A+Main_B which shouldn’t be the case.

What am I missing?

Picture of the combined Main_A+Main_B (Main) and Apt_A+Apt_B (Apt) showing the difference. Green should never be higher than blue, hence my confusion.


I think it may be a configuration problem. If your order was 122923, I see:


Your configuration has 4xAccuCT-H100-200 and 2xECS25-200.

Are you sure two of those CTs are not AccuCT-H064-100?

Sorry, had the incorrect screenshot (great catch) - I had tried changing the config fir Apt from AccuCT-H064-100 to AccuCT-H100-200 to see if it made any range differrence.

They are as follows:
Mains are: AccuCT-H100-200
Apt are: AccuCT-H064-100

I fixed the input screenshot in the first post.


Any other thoughts? Can’t rely on it until I figure this out…

Again, CTs are as follows:
Mains are: AccuCT-H100-200
Apt are: AccuCT-H064-100

Sorry, I thought you indicated the configuration was the problem.

OK, can you post picture of the load-center showing the CTs as installed, and a plot of the Main_A, Main_B, Apt_A and Apt_B over the last 12 hours?

Also, please verify that you don’t have solar or other generation.

No solar generation.

Here you go:

It’s very tight in there and must have been very difficult to install the mains CTs. Looking at the graphs, my suspicion lies with Main_B reading low as Apt_A never exceeds Main_A. while Apt_B always exceeds Main_B.

There are some other subtle clues. Most of the time the two legs appear to be completely independent, indicating mostly 120V variable loads. But there are a few interesting spikes at 01:00 (second one) and 09:00 where both of the mains spike at the same time. That appears to be a 240V load, but the two spikes are not equal in amplitude - Main_B appears to be about half the spike of Main_A in both instances.

It’s very hard to get a CT to read too high. Most of the time when they are off they read low. Moreover the Main_A is validated by Apt_A.

Another clue is that the power factor of Main_B in your original post is 92 where the Apt_B PF is 99. That looks like a predominantly resistive load and Main_B should have a higher PF.

All that suggests to me that the Main_B CT may not be properly seated, may have impurities between the cores, or may be cracked.

The picture doesn’t show the whole box and I can’t tell if the mains run down to the bottom of the box or out the side. I think they run down. If there is more room down there to install the CTs, I’d suggest at least moving the Main_B down there. If not, you have a pair of ECS25-200 clamp-on CTs. You could substitute one of those for Main_B to see if it resolves the difference.

Thanks - I’ll move Main_B to somewhere else to see what happens.
The mains run out the side, but I can connect the CTs on the other side of the panel.