I was recently asked to re-cycle PA system CB on ground by the engineering staff as the system was not working. Without giving it a second thought I did that and the system was working again. Subsequently this made me think. Is this normal? But then what about tripped CBs? What are circuit breakers? The single most “proliferated” item of the electrical system in a modern cockpit is the circuit breaker. These round black heads line the cockpit’s walls and ceiling. AC or DC, ganged, multi- or single-pole, they control,…