Why would my two-pole arc-fault breaker trip when motors are used on other circuits?
Motor loads put a large amount of noise on the line, I have seen this on systems that are separate circuits just another weak point in the arc fault devices. Arc faults have trouble with motor loads, light dimmers that are heavily loaded and electronic ballasts. If the noise on the line is high the arc fault thinks it is part of the circuit. A quality whole house surge suppressor at the service panel may solve this problem.