For temporary wiring over ___ volts, nominal, suitable fencing, barriers, or other effective means shall be provided to limit access only to authorized and qualified personnel.

For temporary wiring over ___ volts, nominal, suitable fencing, barriers, or other effective means shall be provided to limit access only to authorized and qualified personnel.

• A. 250
• B. 1000
• C. 600
• D. 300

Answer: (C)

Key idea: When temporary electrical work involves voltages high enough to pose serious shock and arc hazards, access must be controlled so only trained personnel can approach. For nominal voltages over 600 volts, safety standards require fencing, barriers, or other effective means to limit access to authorized and qualified personnel. This threshold reflects the substantially greater danger at higher voltages and the need for physical separation to prevent accidental contact with energized parts. Why these other numbers don’t fit: 250 and 300 volts are below the level where such fencing is mandated; typical protection at lower voltages relies on standard barriers and safe working practices rather than specialized enclosures. While 1000 volts is certainly hazardous and would require protections, the established requirement cited by the standard uses 600 volts as the trigger point for providing dedicated barriers to restrict access.

Key idea: When temporary electrical work involves voltages high enough to pose serious shock and arc hazards, access must be controlled so only trained personnel can approach.

For nominal voltages over 600 volts, safety standards require fencing, barriers, or other effective means to limit access to authorized and qualified personnel. This threshold reflects the substantially greater danger at higher voltages and the need for physical separation to prevent accidental contact with energized parts.

Why these other numbers don’t fit: 250 and 300 volts are below the level where such fencing is mandated; typical protection at lower voltages relies on standard barriers and safe working practices rather than specialized enclosures. While 1000 volts is certainly hazardous and would require protections, the established requirement cited by the standard uses 600 volts as the trigger point for providing dedicated barriers to restrict access.