NFPA 70E: Performing the electrical flash hazard analysis.

Arc flash hazards pose a serious risk to employee safety; proper safe work practices must be utilized. Electrical equipment > or = 50 volts must be deenergized and locked out/tagged out prior to servicing and maintenance unless doing so would increase hazards or is infeasible. Remember, convenience is not an acceptable reason for keeping equipment energized during servicing and maintenance. If electrical equipment must remain energized during Servicing and maintenance, NFPA 70E should be consulted to determine flash hazard boundaries as well as required PPE. Finally, circuit breakers and electrical disconnects must be marked to warn qualified employees of potential arc flash hazards.