What was the published circuit breaker clearing time in the incident energy calculation example?

What was the published circuit breaker clearing time in the incident energy calculation example?

• A. 0.01 s
• B. 0.05 s
• C. 0.1 s
• D. 0.5 s

Answer: (B)

In incident energy modeling, how long the arc is allowed to exist before the protective device clears it directly influences the energy that could reach a worker. The published circuit breaker clearing time provides a standard duration to use in calculations, representing that arc-present interval. In the example, this time is 0.05 seconds, meaning the arc is assumed to continue for 50 milliseconds before the breaker interrupts it. This relatively short duration lowers the estimated incident energy because the arc releases energy for a shorter period. If a longer clearing time were used, the energy estimate would be higher; a much shorter time would yield even less energy. The 0.05 s value reflects a typical, conservative assumption for fast-acting protection in many calculation scenarios.

In incident energy modeling, how long the arc is allowed to exist before the protective device clears it directly influences the energy that could reach a worker. The published circuit breaker clearing time provides a standard duration to use in calculations, representing that arc-present interval. In the example, this time is 0.05 seconds, meaning the arc is assumed to continue for 50 milliseconds before the breaker interrupts it. This relatively short duration lowers the estimated incident energy because the arc releases energy for a shorter period. If a longer clearing time were used, the energy estimate would be higher; a much shorter time would yield even less energy. The 0.05 s value reflects a typical, conservative assumption for fast-acting protection in many calculation scenarios.