NFPA 70E, the standard for electrical safety in the workplace, is published by the National Fire Protection Association (NFPA). The NFPA has served as an authority in the U.S. on fire, electricity and building safety since 1896. The purpose of the standard is to provide a "practical safeguarding of employees during activities such as the installation, operation, maintenance, and demolition of electric conductors, electric equipment, signaling and communications conductors." NFPA 70E is a voluntary consensus standard, not a law. However, the U.S. Occupational Safety and Health Administration (OSHA) recognizes NFPA 70E as a generally accepted industry practice and has referenced it in citations.
Who NFPA 70E covers
NFPA 70E was developed to protect electrical workers in all industries who work on or near energized parts or equipment that are capable of generating an arc flash. Such equipment would include high-voltage switching and grounding gear, panel boards, switchboards, motor control centers, motor starters, metal clad switchgear, transformers, and meters. Common occupations covered under NFPA 70E include electrical maintenance workers, industrial electricians, and machine operators.
What NFPA 70E requires
Flame resistant clothing is addressed in Chapter 1 of the standard, Safety-Related Work Practices. NFPA 70E requires employers to conduct an arc flash hazard analysis to identify a worker's potential exposure to arc-flash energy. The results of the analysis are then used to determining safe work practices, arc flash protection boundaries, and the appropriate level of personal protective equipment.
The standard states that all equipment must be de-energized before being worked on unless the employer can demonstrate that de-energizing introduces additional or increased hazards or is infeasible due to equipment design or operational limitations. If de-energizing the equipment is not feasible, the employer must establish a "flash protection boundary" which is the minimum distance from an arc source where a person could receive a second-degree burn if an arc flash occurred. When it is determined that an employee must perform electrical work within the flash protection boundary, he or she shall wear protective clothing and all parts of the body within the arc flash protection boundary must be protected.
NFPA 70E requires the use of one of two methods for determining the appropriate level of flame-resistant clothing:
1. Incident Energy Analysis - The employer must determine the potential incident energy exposure of the worker in cal/cm ². Based on this analysis, the worker must wear arc-rated flame-resistant clothing with an Arc Thermal Performance Value (ATPV - measured in cal/cm ²), or EBT greater than the potential exposure level.
2. Hazard Risk Categories (HRC) - To simplify the process, NFPA 70E has developed a table of common electrical job tasks and determined a hazard/risk category for each task. The table above, adapted from NFPA 70E-2009 (Table 130.7(C)(11)), lists the five hazard risk categories, corresponding required minimum arc rating of flame-resistant clothing and the Carhartt HRC color codes.
Look for Carhartt HRC color codes when viewing our online products.
An ATPV is a rating assigned to flame-resistant clothing indicating the level of protection provided. Higher-weight (e.g., thicker, denser) fabrics typically have higher ATPVs and provide increased protection (as does the layering of FR clothing). All Carhartt flame-resistant clothing has the ATPV/EBT marked on the inside label for easy reference. The ATPV is expressed in calories per cm2 and represents the thermal exposure from an electric arc that will create a second-degree burn in human tissue. If the ATPV cannot be calculated because the fabric breaks open, the energy causing the fabric to break open is expressed as the Energy of Breakopen Threshold (EBT). The higher the value the greater the protection.
For general industry, NFPA 70E:
• Mandates that employers conduct a hazard risk assessment to determine the potential arc exposure for employees who work on or near energized parts or equipment. The level of arc exposure is referred to as the ATPV and is measured in calories/cm ² (often called a cal rating).
• Requires employees to wear flame-resistant clothing with an ATPV, or cal rating, equal to or greater than the determined arc hazard.
• Simplifies the hazard assessment and compliance process by creating HRC for common tasks an electrical worker would perform. Therefore, an FR clothing item's HRC rating determines if that item provides sufficient protection for a particular job. As a result, Carhartt FR clothing carries HRC tags. And, unlike some others, Carhartt HRC tags are externally visible, allowing supervisors and safety officers to easily confirm workers are in compliance with NFPA 70E regulation.
For more information or to purchase a copy of the NFPA 70E standard visit the
NFPA web site.