Which rating must an MCC be marked with according to NEC requirements?

Which rating must an MCC be marked with according to NEC requirements?

• A. Short-circuit current rating
• B. Voltage rating
• C. Insulation class
• D. Nameplate horsepower rating

Answer: (A)

Short-circuit current rating is the key label on an MCC. This rating shows the maximum fault current the equipment can safely withstand or interrupt without damage, which is essential for ensuring proper coordination with upstream protective devices. By knowing the available fault current at the installation and the MCC’s SCCR, you can confirm the gear will not fail during a fault and pose a hazard. While voltage rating is also important for defining the operating voltage, the NEC requirement highlighted here is specifically the SCCR because it directly addresses safety during faults. Insulation class and horsepower rating relate to other aspects of the equipment and are not the mandated labeling focus in this context.

Short-circuit current rating is the key label on an MCC. This rating shows the maximum fault current the equipment can safely withstand or interrupt without damage, which is essential for ensuring proper coordination with upstream protective devices. By knowing the available fault current at the installation and the MCC’s SCCR, you can confirm the gear will not fail during a fault and pose a hazard. While voltage rating is also important for defining the operating voltage, the NEC requirement highlighted here is specifically the SCCR because it directly addresses safety during faults. Insulation class and horsepower rating relate to other aspects of the equipment and are not the mandated labeling focus in this context.