Review on XSCORPION CB300L Circuit Breaker Indicator by David Romo

Seems to be what I need. I haven't tested it under load yet, if I do I'll edit it. Not 5 stars because for a 300A current rating you need to use at least 2 #2ga wires or 2/0 wires. The tabs on this switch are not large enough to easily accept connections on #2 or 1/0 or 2/0 wire. This worries me about huge voltage loss and/or side-to-side heating under load.