[Alan Anderson]

It's probably a snap action circuit breaker on the Power Distribution board. They click when they trip, and again when they reset a few moments later. It's very likely that you have a short circuit somewhere. If your PD is one of the newer style, there will be a red light showing next to the tripped breaker.

If you have the power miswired to the output of a Jaguar instead of the input, you'll end up with a short circuit (and a fried Jaguar).