I went with two GEMs:
- I want to monitor quite a few more than 32 branch circuits, plus both legs of my service entrance.
- The voltage difference between both legs of my service can vary quite a bit. It may be as low as one or two volts (not a huge difference) or as high as eight volts. I can speculate why this may be but that tis an entirely different topic. As a result I wanted to monitor both legs independently.
After a kitchen renovation project many years ago, I took the opportunity to completely redo my panel. I didn't change my service, but along with the large number of circuits I added for my kitchen I corrected many of the existing issues and cleaned up the mess left from previous owners. I spent a bit of time arranging the circuits to keep both legs roughly balanced based on expected estimated usage.
After installing CTs on all the circuits, getting the GEMs set up, and starting to monitor my panel I found that the legs were pretty well balanced, with the exception of one circuit. Thanks to my investment I was able to immediately identify this and make the appropriate change in my panel.
Both GEMs are located right next to my panel so I thought about how to keep the install neat. I ended up with a 3/4" flexible conduit from the panel to a 2.5" trough, and mounted both GEMs on top of that trough. I punched another 1/2" hole on the bottom of the trough and inserted a grommet to feed the wires from both power supplies and both PTs through. At the opposite end of the trough is a 1/2" flexible conduit used as a sleeve to pass a pair of Cat-6 cables through, which run back to a 19" rack elsewhere where all of my equipment resides: Below the panel seen at the left edge of the picture is a 1900 (aka 4") box with a pair of duplex receptacles where both PTs and both power supplies are plugged in. In the picture you can see a temporary wire tie around the blue NMT holding these wires where they loop under and into the trough.
All of the CT wires run through the trough into the respective GEMs via the offset nipples on the left side. The serial, power, and PT wires run through the trough into the respective GEMs via the offset nipples on the right side. The extra length of wires are bundled and run down the trough in a single loop.