Grounding requirements for fastened-in-place equipment operating at "over 150 volts to ground" apply to which voltage systems?

The grounding requirements for fastened-in-place equipment operating at "over 150 volts to ground" apply to specific voltage systems where the potential of the system exceeds this threshold. In this context, the correct choice refers to a 120/240, 3-phase, 4-wire system. This system operates at a higher voltage configuration that meets the criteria for grounding requirements under the National Electrical Code (NEC).

This type of system typically includes three phase conductors and a neutral, which is utilized in many commercial and industrial applications. Since it operates above the 150 volts to ground threshold, it necessitates compliance with the grounding requirements established to ensure safety and functional reliability. Such requirements are critical for protecting personnel and equipment from electrical faults.

Other options include systems that may either not meet the voltage requirement or do not provide the necessary configuration for the safety provisions associated with fastened-in-place equipment at elevated voltage levels. Understanding the specific grounding requirements for different voltage systems is essential for maintaining safety standards in electrical installations.