Work on a 480-volt panelboard supplied by a molded-case circuit breaker with available fault current of 18 kiloamps. Based on the PPE Category method, what PPE category is required?

Work on a 480-volt panelboard supplied by a molded-case circuit breaker with available fault current of 18 kiloamps. Based on the PPE Category method, what PPE category is required?

• A. PPE Category 0
• B. PPE Category 1
• C. PPE Category 2
• D. PPE Category 3

Answer: (C)

PPE category method uses the voltage and the available fault current to estimate the arc-flash energy and assign a protection level. For a 480-volt system with an available fault current of 18 kA, the table used in NFPA 70E places this scenario in the category that corresponds to a high but not the maximum arc energy. That is Category 3. This means you’d plan for a substantial level of arc-flash protection, such as arc-rated clothing, a face shield or hood, and insulated gloves, with additional protections as required by your program. Lower categories would not provide enough protection for this energy level, and the top category would apply to even higher energy scenarios.

PPE category method uses the voltage and the available fault current to estimate the arc-flash energy and assign a protection level. For a 480-volt system with an available fault current of 18 kA, the table used in NFPA 70E places this scenario in the category that corresponds to a high but not the maximum arc energy. That is Category 3. This means you’d plan for a substantial level of arc-flash protection, such as arc-rated clothing, a face shield or hood, and insulated gloves, with additional protections as required by your program. Lower categories would not provide enough protection for this energy level, and the top category would apply to even higher energy scenarios.