A closer look at OSHA's electrical power standard 1910.269
Answered by Josh Moody, vice president of technical services, Westex Inc., Chicago.
OSHA issued a proposed rule regarding 29 CFR 1910.269 in June 2005. Changes to the clothing requirements are in recognition of the electrical arc flash hazard. Electric arc flashes can ignite non-flame-resistant clothing and cause severe injury to workers in the power generation, transmission and distribution industry.
This is not a new idea. The issue is that the industry and OSHA realize the magnitude of the arc flash hazard and the frequency with which it occurs. For years the industry lumped together arc flash injuries with shock injuries. Only in the last decade has the industry really grasped the true number of injuries due to electric arc flashes.
OSHA is proposing the use of flame-resistant clothing to protect workers from the thermal effects of electric arc flashes. This involves first assessing the workplace to see if an employee is exposed to hazards from flames or electric arcs. For each employee exposed to these hazards, a reasonable estimate should be made of the maximum heat energy they could potentially be exposed to.
For this hazard risk analysis, multiple tools are available. These range from simple equations to the protection schemes of the National Electric Code, NFPA 70E and the Institute of Electrical and Electronics Engineers 1584 standards, to the several commercial software programs now available. OSHA is proposing a new Appendix F, which will discuss the various methods of calculation tools available. Presently, it seems OSHA is not limiting the methods that can be used for this calculation.
The proposed rule states the calculations need not estimate the energy for each job task. Instead, employers may make broad estimates that cover multiple system areas. This is provided the employer uses reasonable assumptions about the energy exposure distribution throughout the system, and the estimates represent the maximum exposure for those areas.
The next step is for the employer to ensure the employee does not wear clothing that can melt onto the skin or ignite and continue to burn when exposed to the energies that were estimated.
Additionally, the standard proposes requiring flame-resistant clothing when:
- The employee is subject to contact with energized circuit parts operating at more than 600 volts
- The employee's clothing could be ignited by flammable material in the work area that could be ignited by an electric arc
- The employee's clothing could be ignited by molten metal or electric arcs from faulted conductors in the work area
Many utilities currently are using some form of clothing program. All utilities will have to perform hazard analysis for their various systems. Then, they will have to decide on what fabrics and products will provide the appropriate levels of protection. In the end, this will mean that more workers will be protected in the power generation, transmission and distribution industry than ever before.