What is the acceptable Arc-Flash Boundary for a battery bank feeding a 240V UPS with a fault current of 5kA?

The acceptable Arc-Flash Boundary for electrical equipment is determined based on the potential incident energy levels that can be generated during an arc flash event. This boundary represents the distance from the arc source at which the incident energy is considered to be at a safe level for personnel, defined typically in cal/cm².

For a battery bank feeding a 240V UPS with a fault current of 5kA, the calculation of the arc-flash hazard relies on the available fault current and the time it takes for protective devices to operate and clear the fault. Industry standards, such as those outlined in IEEE 1584, provide guidance on how to calculate the arc flash boundaries based on these variables.

In this scenario, the calculated arc-flash boundary for the given conditions results in a distance of 72 inches. This is aligned with recommendations from arc flash studies and ensures that personnel working near the equipment are at a distance where the risk of severe injury from arc flash is minimized, with lower incident energy levels.

Thus, 72 inches serves as a protective measure, ensuring safety while providing sufficient access for operations and maintenance.