Under NFPA 70E, there are only two instances in which an employee can work on live parts. In these situations, a work permit must be completed and approved by an authorized person.
- When de-energizing would interrupt essential life support, emergency alarms or ventilation systems.
- When the organization can demonstrate that de-energizing the system would introduce additional or increased hazards or that it is infeasible due to equipment design or operational limitations.
The permit must be posted in an appropriate and obvious location where the energized work is taking place for the duration of the task.