[rotorwrench]

You may be getting an intermittent short in the circuit somewhere. The circuit breakers have a heat sensitive bi-metalic strip that opens the circuit when it heats up from a short or high resistance ground. Inspect the wiring real well and clean all related electrical connectors/ground connectors. If all checks serviceable, you may just need a new circuit breaker.

The relay should be for the horns.

Kerby