NFPA 70E, CSA Z462 and OSHA 1910 are very clear: equipment must be de-energized ("electrically safe work condition") if the worker is exposed to a possible hazard (within the limited approach boundary, or performing a task that increases risk of arc flash).
But when is it OK to use appropriate PPE and work?
1.When working at less than 50V.
2.When de-energizing could "introduce additional hazards or risks" - for example if it could cause someone's life support system to crash.
3.When it is "infeasible" to perform the task de-energized - as with many diagnostic tasks that require a loaded system.
Exceptions #1 and #2 are pretty cut and dry. Exception #3, however, is easily the most misunderstood and misused exception to the "de-energize it" rule.
In many facilities, "infeasible" has been (intentionally or unintentionally) misinterpreted to mean "inconvenient." Too many times, Energized Work Permits are completed, and work is performed because the facility manager does not want to interrupt production, or because administrative staff "can't be without power" during a lighting ballast replacement (one of the most common sources of workplace electrocution). These excuses are not infeasible, they are just inconvenient.
How inconvenient would it be, though, if you had to inform a family that they lost their husband and father so that the administrative staff didn't have to work with less light for a few minutes? Tragically, multiple facilities are making that call every year.
Is your facility misinterpreting exception #3?
Tip Provided By: Tim Rohrer, President of Exiscan