At what voltage level does the minimum depth of clear working space exceed 10 feet?

The correct choice indicates that at voltage levels above 75 kV, the minimum required depth of clear working space exceeds 10 feet. This is based on safety standards and electrical codes designed to protect workers from the hazards associated with electrical equipment.

As the voltage level increases, the potential danger grows, necessitating larger distances to ensure safety. High voltage systems, particularly those above 75 kV, require greater clearances to mitigate the risk of electrical shock and arcing. This requirement is rooted in the understanding that at higher voltages, the energy released during a fault can be significantly greater, making it critical to maintain a safe working environment.

Lower voltage levels, such as those under 75 kV, do not necessitate as extensive a working space. For instance, voltages in the ranges of 2,501 to 9,000 volts, 601 to 2,500 volts, and 151 to 600 volts require less clearance because the risks associated with electrical shock and arc flash are lower, allowing for reduced safety zones compared to higher voltage situations. Hence, those options do not require greater clear working space beyond the 10-foot threshold indicated for voltages above 75 kV.