NFPA 70E is the result of several years of research and development. O.S.H.A. (the Occupational Health and Safety Administration) realized that there was no real standard to implement electrical safety in the workplace and requested that the NFPA provide documentation that would properly and correctly assist OSHA with administration of safety procedures.
A direct result of the request to provide this document is the new Flash Protection Standard (provided in NFPA 70E).
Many workers have been flashed, shocked, maimed, and even lost their lives either as a result of electrocution or as a result of the Arc Flash Hazard. Not previously studied, it has now become very evident that a short circuit can cause many things to happen very quickly and in a chain reaction.
Let’s walk through a possible scenario.
1) An electrician is troubleshooting a 480 volt disconnect and attempting to dislocate a defective part. While using a screwdriver, the screwdriver slips and crosses two phases causing a 480 phase to phase short circuit.
2) As soon as the short circuit is made, an arc flash occurs (temperatures upwards of 20,000 degrees. Skin can only take 120 degree heat before major damage occurs.
3) As the screwdriver and the disconnect parts begin to arc another even more dangerous phenomenon occurs. The copper and steel both begin melting and attempt to eliminate the short circuit by forcing themselves apart (arc blast). Another words, molten metal spews away from the disconnect directly into the face and eyes of the worker.
4) Another result of the arc blast is the force cause by the rapid expansion of the air as the Arc Blast occurs. This expansion can easily be enough to throw a worker back sometimes even across the room. This forces the air out of the lungs.
5) If the air is forced out of the lungs, the natural reaction is to gasp for air, thus ingesting gas , molten metal, and vapors into the nose, throat, and even lungs.
6) Depending on the severity of this chain reaction, personnel can receive life altering damage and even death.
The reason for NFPA 70 E is to address this type of occurrence and to provide standards for Electrical Safety in this and other scenarios to provide practices that will better prepare and protect personnel from both Electrical Arc Flash and electrocution.
This standard also addresses the need and correct procedures for Electrical Work Permits, proper Lock Out Tag Out Procedures, and much more. Any person working in or around electrical equipment is affected by 70 E.
Also addressed are proper installation methods that limit or significantly reduce the exposure to electrical hazards. These procedures provide both methods and prescribe P.P.E. to safely perform many tasks on energized equipment.
Because electricity is dangerous and electricians encounter many hazards that may or may not be able to be addressed through Electrical safety talks or electrical safety tips, many states are mandating electrical continuing education that incorporates NFPA 70 E.
David (Dave) Witherspoon