Elevator motor overcurrent protection
Elevator motor overcurrent protection
(OP)
There is an elevator with a 30hp 480v 3 phase motor. There is a 100 amp circuit breaker with a shunt trip in the elevator room. Based on 80 starts per hour, what is the minimum and maximum size the circuit breaker can be at the electrical panel?






RE: Elevator motor overcurrent protection
The number of starts per hour doesn't really come into play. The duty cycle rating of the motor can be used to allow a smaller than normal motor feeder, and this could impact your breaker size.
If the feeder is sized larger than required for a single motor feeder, then the breaker is sized strictly on the basis of the ampacity of the feeder.
Hope that helps.
RE: Elevator motor overcurrent protection
Bung
Life is non-linear...
RE: Elevator motor overcurrent protection
99NEC620 Part G seems to treat it as a conventional motor system, along with a selective-coordination requirement.
Depending upon age of the equipment, it may be desirable to compare currently installed with submittal/as-built/maintenance documentation and drawings.
What sort of problems are at hand? Overcurrent-device sizing may be an engineering/design matter and not so much a code issue.