Does NEC 408.6 require panelboards, switchboards, and switchgear to have a short-circuit current rating that is less than the available fault current?

Does NEC 408.6 require panelboards, switchboards, and switchgear to have a short-circuit current rating that is less than the available fault current?

• A. Yes
• B. No
• C. Only for outdoor equipment
• D. Only for voltage above 480 V

Answer: (B)

SCCR—short-circuit current rating—is the maximum fault current that panelboards, switchboards, and switchgear can safely withstand and interrupt. NEC 408.6 requires that this rating be not less than the available fault current at the equipment’s line side. In practice, you choose equipment whose SCCR matches or exceeds the worst-case fault current the system could deliver; otherwise the equipment could be damaged or fail to interrupt the fault, creating serious safety hazards. This requirement applies regardless of outdoor vs indoor placement or voltage level within typical ranges, and it ensures safe operation by accommodating the strongest possible fault the system might produce. Therefore, stating that the rating should be less than the available fault current is not correct.

SCCR—short-circuit current rating—is the maximum fault current that panelboards, switchboards, and switchgear can safely withstand and interrupt. NEC 408.6 requires that this rating be not less than the available fault current at the equipment’s line side. In practice, you choose equipment whose SCCR matches or exceeds the worst-case fault current the system could deliver; otherwise the equipment could be damaged or fail to interrupt the fault, creating serious safety hazards. This requirement applies regardless of outdoor vs indoor placement or voltage level within typical ranges, and it ensures safe operation by accommodating the strongest possible fault the system might produce. Therefore, stating that the rating should be less than the available fault current is not correct.