WHAT STANDARDS ARE USED FOR ELECTRIC POWER GENERATION, TRANSMISSION AND DISTRIBUTION?

 flame resistant

OSHA’s Final Rule on Electrical Protective Equipment (OSHA 1910.269) prohibits clothing that, when exposed to flames or arcs, could increase the extent of wearer injury. Employers must determine appropriate clothing based on an evaluation of potential hazards in the work environment. Clothing made from flame-resistant materials is acceptable under the Rule, i.e., clothing that meets the requirements of ASTM F1506. Untreated cotton or wool fabrics weighing at least 11.0 oz. or heavier untreated cotton or wool fabrics are acceptable under limited conditions identified by OSHA. (1.)

(1.) Arc conditions in the Duke Power Company videotape, which was the primary basis for OSHA’s determination, were a 3800 ampere, 12 inch (approx) electric arc that was approximately 12 inches from the material. The arc lasted for 10 cycles or 0.167 seconds.

The National Electrical Safety Code (NESC®) is published by the IEEE. It sets the ground rules for practical safeguarding of persons during the installation, operation, or maintenance of electric supply and communication lines and associated equipment.

The NESC requires that the employer determine potential exposure to an electric arc for employees who work on or near energized parts or equipment operating at 50 volts or greater. If the exposure is greater than 2 cal/cm

 

2, employees are required to wear clothing with an arc rating not less than the anticipated level of arc energy as determined by completing a detailed arc hazard analysis or by using tabulated values found in table 410-1. Table 410-1 outlines equipment types, nominal voltage ranges and the arc thermal performance value (ATPV) cal/cm2, for clothing or clothing systems for employees working on or near energized lines, parts or equipment. Depending on the voltage, effective arc ratings can range from 4 calories to as much as 60 calories/cm2. Certain meltable fabrics are not allowed.

The NESC also contains requirements that risk factors such as equipment condition and work methods must be considered in implementation of an arc flash program and that a job briefing must be conducted by a first-level supervisor or person in charge.

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