What energy threshold defines the Arc Flash Boundary expressed in cal/cm2 (and its SI equivalent)?

What energy threshold defines the Arc Flash Boundary expressed in cal/cm2 (and its SI equivalent)?

• A. 1.2 cal/cm2 (5 J/cm2)
• B. 2.0 cal/cm2 (10 J/cm2)
• C. 0.5 cal/cm2 (2.5 J/cm2)
• D. 3.0 cal/cm2 (15 J/cm2)

Answer: (A)

The Arc Flash Boundary is the distance from an arc fault at which the incident energy is high enough to cause a potential burn on unprotected skin. The standard value used to define this boundary is 1.2 cal/cm^2, which is about 5 J/cm^2. This threshold is chosen because it corresponds to the energy level at which a second-degree burn can occur with a brief exposure, so it marks the point where PPE and safety measures become necessary. Therefore, the boundary is defined by 1.2 cal/cm^2 (5 J/cm^2). The other options represent different energy levels, not the widely adopted boundary value.

The Arc Flash Boundary is the distance from an arc fault at which the incident energy is high enough to cause a potential burn on unprotected skin. The standard value used to define this boundary is 1.2 cal/cm^2, which is about 5 J/cm^2. This threshold is chosen because it corresponds to the energy level at which a second-degree burn can occur with a brief exposure, so it marks the point where PPE and safety measures become necessary. Therefore, the boundary is defined by 1.2 cal/cm^2 (5 J/cm^2). The other options represent different energy levels, not the widely adopted boundary value.