Arc flash protection first became an issue of serious study in the early 1980s when in the IEEE Transactions on Industry Applications there appeared an article by Ralph Lee titled: “The Other Electrical Hazard: Electric Arc Blast Burns.” These early studies convinced several companies, particularly those in the petrochemical industry, that too many workers were suffering burn injuries from electrical safety incidents. A consequence was that several companies took steps to establish the first set of known practices designed to better protect employees and electrical personnel who were working on energized electrical equipment.
While petrochemical companies were some of the first to recognize the need for electrical safety defence, because the dangers apply to all electrical installations. Although the amount of energy released in an electrical safety explosion may be greater for higher voltage installations found in some petrochemical and other industrial plants, the sheer volume of low voltage equipment in commercial and industrial facilities means that installations like these account for the greatest number of electrical safety incidents.
The best way to prevent personal protection injuries from occurring is to de-energize equipment before beginning work. Standards are designed to protect workers and the workplace in the few instances where turning off the power could create a greater hazard to people or processes than leaving it on. These standards place responsibility on employers and facility owners for establishing safe practices to protect their workers against arc flash incidents.
The goal of these standards, such as NFPA 70e, is to keep electrical workers free from the hazards of shock, electrocution, arc flash, and arc blast. It's important, therefore, to understand the requirements set forth in the standards for employee safety, the importance of an electrical safety program, the responsibilities of employer and employee, and the processes and best practices set forth in various industry standards and regulations.
Industry standards.
Four separate industry standards establish practices for the prevention of electrical explosion incidents:
OSHA 29 Code of Federal Regulations (CFR) Part 1910, Subpart S
This regulation states, in part, "Safety related work practices shall be employed to prevent electric shock or other injuries resulting from either direct or indirect electrical contacts… ." OSHA also addresses the qualification of workers exposed to electrical shock hazards and the provision for protective equipment appropriate for the work to be performed. OSHA enforces safety practices and cites to the NFPA requirements.
NFPA 70e-2004, National Electrical Code
Section 110.16 requires that companies place a warning label on electrical equipment likely to consitute an electrical safety hazard. This field marking can be generic or very specific, whichever the company selects. Future revisions of the NEC standard may require more detailed information on this label.
NFPA 70E-2000, Standard for Electrical Safety Requirements for Employee Workplaces
NFPA 70E can be considered the “how to” standard behind OSHA enforcement. It provides the detailed actions companies must take to be in federal compliance.
Specifically:
- Safety program with defined responsibilities
- Calculations for the degree of electrical safety hazard
- Personal protective equipment (PPE) for workers
- Training for workers
- Tools for safe work
- Warning labels on equipment
IEEE Standard 1584-2002, Guide for Electrical Safety Regulation
In order for the warning labels to carry enough information to show the danger zone for electrical safety conditions, companies must determine that area within which only qualified workers should enter—the protection boundary. IEEE 1584 provides a method to calculate the incident energy in order to specify the level of PPE required for workers.
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