When a single phase of a 3-phase line is grounded, how is the minimum approach distance to the ungrounded deenergized phases affected?

When a single phase of a 3-phase line is grounded, the minimum approach distance to the ungrounded deenergized phases is reduced. This occurs because grounding one phase alters the voltage distribution and potential difference across the phases.

In a 3-phase system, the phases maintain a fixed voltage relationship to each other. If one phase is grounded, the other two phases will experience a reduction in their effective phase-to-ground voltage. Consequently, the risk of electric shock or arc flash scenarios diminishes, allowing for a safer working environment.

The grounding stabilizes the voltage levels, which means that the amount of protective distance required when approaching the ungrounded phases can actually be less than in a scenario where all phases are floating. Thus, the grounding effectively reduces the necessary approach distance for safe maintenance and troubleshooting activities. This adjustment is critical for ensuring that workers can safely execute their jobs while minimizing the risk of electrical hazards.