There is no way to know if a circuit breaker will operate properly under fault or overload conditions unless it is tested, preferably by a primary injection test. (Refer to NEMA Standard AB 4 “Guidelines of Inspection and Preventive Maintenance of Molded Case Circuit Breakers Used in Commercial and Industrial
• Testing is recommended at start-up and every three years thereafter
• Circuit breaker must be de-energized to perform test
• For primary current injection testing, a power source capable of supplying 100 amps at 208 or 480 volts is required to power the test set
Emerson/Liebert has the largest service organization in the world dedicated to maximizing availability of infrastructure required for mission-critical systems.