Is it permissible to install equipment when its SCCR equals the calculated available fault current?

Is it permissible to install equipment when its SCCR equals the calculated available fault current?

• A. Yes
• B. No
• C. Only with AHJ approval
• D. Only for equipment rated above 3,000 A

Answer: (A)

This question tests that the Short-Circuit Current Rating (SCCR) of equipment must meet or exceed the available fault current at the installation. The available fault current is the maximum current that could flow during a fault, given the source, wiring, and protective devices. The SCCR is the highest fault current the equipment can safely interrupt or withstand. The rule is that SCCR must be not less than the available fault current. Therefore, equality is acceptable—if the SCCR exactly matches the available fault current, the equipment is still within its rated capability and may be installed. In practice, many designs aim for a margin above the AFC, but equality satisfies the requirement.

This question tests that the Short-Circuit Current Rating (SCCR) of equipment must meet or exceed the available fault current at the installation. The available fault current is the maximum current that could flow during a fault, given the source, wiring, and protective devices. The SCCR is the highest fault current the equipment can safely interrupt or withstand. The rule is that SCCR must be not less than the available fault current. Therefore, equality is acceptable—if the SCCR exactly matches the available fault current, the equipment is still within its rated capability and may be installed. In practice, many designs aim for a margin above the AFC, but equality satisfies the requirement.