So after a few hours of operation my instrument circuit breaker trips, shutting off my chartplotter and other gauges. If I try an immediate reset it trips again. If I wait about 1/2 hour I can reset the breaker. I've also noticed that just before it trips, all lights that are on go dim and if the engine is running it labors significantly. This makes me think that there is a good, solid short to ground somewhere rather than a defective instrument or light intermittent short. Or possibly that the circuit breaker itself is defective? There is a 12V power outlet in the cockpit that is energized with the instrument circuit. Any thoughts on how to pursue this?