Hello @jonsand
I’m confident suitable CTs can be sourced. I can get any of these CTs with about a month lead time: https://www.echun-elc.net/Products.asp?BigClassID=81. Any unit that has a 50mA output option is available. It’s also possible to have the burden resistors changed to accommodate other CTs. The IoTaWatt firmware is designed to be able to do that.
I have a limited number of large CTs in stock. With a 2000 A service, I think it’s either multiple parallel feeds or bussbars. CTs are available for both.
Most CTs will go somewhat beyond their stated range without much loss of liniarity but they do start to saturate and phase shift and distortion start to effect the results. The major limitation is the input current to the IoTaWatt. The stated range is 50mA, and the absolute limit is about 58mA. Beyond that, while no damage would be done, the range is clipped and accuracy would fall off sharply. That range is a function of the burden resistor, so it can be changed. When you have more detailed specs, I can be specific about the options.