What is an acceptable flash protection boundary for a panelboard with specific fault conditions?

The correct answer of 36 inches as the acceptable flash protection boundary for a panelboard in specific fault conditions is based on the National Fire Protection Association (NFPA) 70E standards, which govern electrical safety in the workplace. These standards specify safe working distances to protect personnel from potential arc flash hazards, considering the incident energy levels that can be present during such events.

The 36-inch boundary is vital as it represents the minimum distance at which workers can safely approach energized electrical equipment without the risk of injury from an arc flash. This distance is determined by evaluating factors such as the available fault current, the equipment's protective devices, and the clearing time of those devices. It is essential to ensure that all personnel understand and adhere to these boundaries to minimize injury risk while working near or on electrical systems.

Other distances, while potentially considered, are either too close or do not comply with the NFPA 70E criteria, which requires the use of the prescribed approach distances based on calculated incident energy levels.