Switchgear and Motor Control Centers

In industrial environments, electricity is provided to loads from load centers, including switchgear and motor control centers (MCCs). Both of these load centers are having hinged doors for easy internal access. Smaller electrical components can be housed in enclosures that are classified by NEMA Type, which defines the ability of the enclosure to resist environmental factors. Several important ratings apply to both switchgear and MCCs. A continuous current rating limits the temperature rise of the load center components, particularly the insulation. A short-circuit current rating determines both the interrupting capability of the circuit breakers and fuses, and the mechanical strength of the bracing and support systems. Arc flash hazard must be addressed to determine safe working procedures around energized equipment. NFPA standard 70E and IEEE standard 1584 address the arc flash hazard by providing guidance for performing calculations to determine the incident energy during an arc flash event.