NFPA 70E, or the NFPA's Standard for Electrical Safety in the Workplace, outlines specific practices to be followed in protecting a workplace from electrical hazards such as arc flash.
The NFPA's Standards
The National Fire Protection Association (NFPA) is a non-profit organization that produces standards for safety. For example, they publish the National Electrical Code (NEC), which describes proper installation of electrical systems. That code is incorporated into law in many parts of the United States.
For safe work practices in an existing facility, the "go-to" standard is NFPA 70E. While it is not legally required in most areas, it is widely respected and followed, and is used as a reference for safe practices worldwide.
Electrically Safe Work Conditions
The primary focus of NFPA 70E is the establishment of an electrically safe work condition. This means that the equipment is fully de-energized, and cannot be re-energized while work is still being performed. The following steps should be followed to create an electrically safe work condition:
- Determine all possible sources of electrical energy to the equipment.
- Interrupt load current and open disconnecting devices for all sources.
- Where possible, visually confirm that disconnecting devices are open.
- Follow appropriate lockout/tag-out procedures.
- Verify that equipment is de-energized using a voltmeter. Until equipment is tested, assume that it is still energized.
- Use grounding devices where the possibility of stored energy or induction exists.
Creating an electrically safe work condition is the best defense against electrical hazards such as arc flash (a sudden and dangerous burst of energy) or electric shock. As a result, this procedure should normally be used in all electrical work, with the following exceptions:
- De-energizing equipment would create a greater hazard. Examples include life-support equipment, ventilation equipment in a hazardous environment, or similar safety equipment that requires an energized state.
- De-energizing is not possible, due to equipment design. If the equipment is part of a larger, continuously-operating system, for example, it may not be possible to de-energize the necessary parts.
- The nature of the work to be performed requires that equipment be energized. A simple example would be checking voltage.
The Electrical Safety Program
To ensure consistent application of safety procedures, NFPA 70E requires companies to create a written program outlining that company's electrical safety program. These programs should include assessments of any electrical hazards in the facility, such as arc flash; procedures for the necessary maintenance on the facility's equipment; lockout/tagout procedures for ensuring an electrically safe working condition; and the permission process for potentially dangerous work. Up-to-date and accurate information on the facility's electrical systems are also needed, such as one-line diagrams and equipment specifications.
The goal of this kind of program is to protect the workers and facility from harm. An effective system should establish a culture of safety awareness that includes all employees. One key part of this safety awareness is providing information about any hazards that exist, so NFPA 70E includes detailed requirements for hazard and equipment labeling. The current edition of the standard requires detailed labels, not just generic warnings.
NFPA and Arc Flash
One of the major concerns in electrical safety is the risk of an arc flash. NFPA 70E focuses a significant part of its content on this one hazard. Even though arc flashes are rare, their occurrence is unpredictable, and they can be incredibly destructive.
The standard requires protective boundaries around potentially-hazardous equipment as a beginning step for safety. Next, informative and detailed labels are required for equipment that may pose an arc flash hazard. Finally, the last line of defense against an arc flash is a worker's personal protective equipment (PPE), and NFPA 70E provides recommendations and requirements for that equipment.