- The motors on vehicle lifts have relatively short periods of operation (usually less than one minute) with long periods of rest between these periods of operations. This is defined as Intermittent Duty according to the National Electric Code (NEC) as described in Article 100 - definitions.
- According to NEC Article 430-33, a motor that is used as intermittent service is permitted to be protected against overloads by the branch-circuit short-circuit and ground-fault protection device.
- According to NEC Article 430-33, a motor cannot automatically restart after an overload trip if personal injury can result. An ATO could cause an automatic restart by masking a failed switch that has stayed in the normally closed position. This condition would allow the motor to restart after the ATO reset.
- With Intermittent Duty, the overcurrent protection is more likely to trip before an ATO; this renders the ATO useless.
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