NFPA 70E is the primary standard for electrical safety in the workplace. Published by the National Fire Protection Association, it serves as the authority in the U.S. on fire, electricity and building safety. 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.” The U.S. Occupational Safety and Health Administration (OSHA) recognizes NFPA 70E as a generally accepted industry practice – often referencing it in citations. NFPA 70E does not have the power of a law, but is a voluntary consensus standard.
Who is covered by NFPA 70E?
Electrical workers in all industries who work on or near energized parts or equipment that are capable of generating an arc flash. Examples would be electrical maintenance workers, machine operators and industrial electricians. Typical equipment would include high-voltage switching and grounding gear, panel boards, switchboards, motor control centers and starters, and transformers.
Role of FRC (flame resistant clothing) in meeting NFPA 70E
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. Flame resistant clothing may be indicated.
For safe working practices, all equipment must be de-energized before being worked on unless the employer can demonstrate that de-energizing introduces hazards or creates problems due to equipment design or operational limitations. If de-energizing the equipment is impractical, the employer must establish a “flash protection boundary”. This is the minimum distance from an arc source where a person could receive a second-degree burn if an arc flash occurred. If the employee must perform electrical work within the flash protection boundary, the standard calls for wearing protective clothing as one measure of safety.
NFPA’s guidance on determining risk:
Perform an Incident Energy Analysis to determine the potential incident energy exposure of the worker. With the results of this analysis, the employer will select arc-rated flame-resistant clothing with an Arc Thermal Performance Value (ATPV), higher than the risk level. NFPA has established a table of common electrical job tasks, and a hazard category for each of these tasks. These are referred to as Hazard Risk Categories (HRC). The ATPV is a rating assigned to flame-resistant clothing noting the level of protection provided. 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.