Troubleshooting Subpanel

I have a pretty simple use case/setup I’m trying to solve for. I have a 125 amp panel and 50 amp sub panel I’m trying to monitor. Per the photos attached I have 2 X 200 amp CTs attached to each line of the main, and 2 X 50 amp CTs attached to each line of the sub panel. I have a headphone y-splitter merging both of the sub panel lines into 1 spot in the IotaWatt. Problem is, per the screenshots, my sub panel is reading a higher input than my main supply… How is that possible? Do I have something misconfigured/not set up?


There are a number of things that could be causing this. First, I’d like to see the inputs setup display.

Do you know if your panel is 120V/240V or 120V/208V? Sometimes these types of panels, when used in an apartment or condo, use two legs of three phase (120V/208V) instead of split-phase (120V/240V). The former needs to be configured differently.

If you have a voltmeter, you can simply check the voltage between the two incoming mains. It should be 240V or 208V.

Confirming I have 240v.

Screenshot of input setup below…

Durr I think I just realized the issue… Changed both the ECS24400 CTs to ECS24200 and the wattage now looks correct… Is that it? Are all your CTs model ECS24200?

Your mains should be AcuCT-H100-200 and the sub-panel should be AcuCT-H040-50.

Given 240V, both of the CTs in the picture appear to be oriented the same way. When combining two different legs, one should be reversed. Also, with 50A CTs, you will be limited to about 7kW for the sub-panel, which may be OK, but if you want full range, you can get it with a single 100A CT with both conductors passing through in opposite directions as in this photo.