Which event is commonly cited as a potential source of hazardous voltage that can energize equipment unexpectedly?

• A. Lightning-induced voltage
• B. Regular maintenance
• C. Cooling
• D. Lighting fixtures turned off

Answer: (A)

Lightning-induced voltage is a common source of hazardous voltage that can energize equipment unexpectedly because a lightning strike sends a huge surge onto the power network. That surge can propagate along lines and through transformers, sometimes finding its way into equipment or wiring through normal paths or via capacitive and inductive coupling. The result is a transient voltage on conductors or components that technicians might assume are de-energized, creating shock or arc-flash hazards if touched or opened without proper precautions. This is why safer work practices emphasize treating exposed conductors as potentially energized, using appropriate PPE, and verifying absence of voltage with proper testing and lockout/tagout procedures before any work.

Regular maintenance isn’t inherently a source of hazardous voltage; it can involve energized work if not planned correctly, but it’s not the typical cause of unexpected energization described here. Cooling is simply a process and does not introduce voltage. Lighting fixtures turned off reduce power delivery to a fixture and do not by themselves create unexpected energization of other equipment.