I got a call today regarding a rooftop breaker tripping. It is at a restaurant with a subpanel on the roof that feeds two ac units and some smaller exhaust fans. The breaker that feeds the panel is tripping every once in a while. twice yesterday, none today. I checked the amperage at about 6:30 this evening with both ac units running. It was pulling 75 amps on a 90 amp breaker and the wire was quite warm. It has #2 alum wire feeding the panel which runs for about 45ft in pvc on a white rubber room.
Could the acs running when its 90 degreees, with the increased ambient temperature cause the breaker to trip? I know that it could cause detioration of the wire. I did change the two 60 amp breakers on the ac out last year at this same time beacause they were crumbling from being to hot.
