Which of the following systems does not require grounding due to voltage limitations?

In electrical systems, grounding is often mandated to ensure safety and to prevent electrical shock hazards. A key factor in determining the need for grounding is the voltage of the system. Generally, systems operating at higher voltages are more susceptible to hazardous conditions, which typically necessitate proper grounding procedures.

The 480V, three-phase delta system, while it has considerable voltage, is frequently used in industrial applications where specific grounding practices may be needed to ensure safety. However, such systems can also be designed in ways that allow them to operate without relying heavily on grounding under certain conditions, especially if they are considered separately derived systems or are used with specific equipment that manages overvoltage risks.

In comparisons within the options, lower voltage systems generally have more stringent grounding requirements. Higher voltage systems like the 480V delta can sometimes be configured in a manner that does not necessitate grounding under specific conditions or applications, particularly when using double insulation or isolation transformers.

In summary, the 480V, three-phase delta system is recognized for its operational flexibility that can lead to scenarios where grounding may not be necessary, especially when the application details and electrical design considerations permit such configurations.