I will give you some quick background. I live in Texas where we just lost power for about 5 days. I am buying a generator and plan to use it to back feed my electrical panel using a mechanical interlock for safety. This prevents me from back feeding the grid as it should. I have 200A 240V service that comes in on 2 live lines. I want a simple light could be neon or led or other that will indicate if power has returned to mains. I would like to use a split core current transformer so that I don’t have to disconnect these live wires. I am having difficulties finding split core current transformers rated for 200A. I see an abundance of 100A that go all the way to 300v. I am looking for a simple to install cost effective way to know if power has returned as I will have to manually switch back. At some point I may invest in an Auto Transfer Switch but these are outside my ability to afford. Any help would be greatly appreciated.