Arc Flash & Blast

 

Arc flashes are caused by an electrical equipment failure (like a short circuit) or human error (such as holding a metal object too close to energized equipment). If you have two energized points which are not contacting each other solidly, the current can jump from one point to the other. This is called an electric arc or arc flash.

One-second duration
Unlike a flash fire, an electric arc can begin and end in less than a second. Bystanders see a flash and hear an extremely loud boom and it is over.

Electric arc
A person can be severely injured or killed by the huge amount of heat generated by this arc. Temperature of the arc can range from 15,000 to 35,000 degrees F. You can imagine what this heat can do to the human body. (Heat in excess of 122 degrees F. can cause third degree burns, which do not heal.)

Flying molten metal
The arc also immediately turns the electrical conductors into molten metal droplets that fly away from the source at near the speed of sound. These projectiles can travel quite a distance, starting clothing and other materials on fire.

Arc blast
Not only does the electric arc generate an excessive amount of heat, this heat causes an intense pressure wave that usually throws the employees working nearby away from the arc. This wave is so strong it can break ear drums and cause concussions and broken bones.

Explosions and/or fire
The heat from electric arcs can ignite combustible or flammable vapors in the air causing an explosion. Materials stored nearby can also start on fire.

Personal Protective Equipment (PPE)
Whenever electrical workers have the chance to be exposed to an electric arc they must wear clothing and eye protection resistant to the flash. Make sure your employer provides you with the necessary PPE. (Part II, Chapter 3 of NFPA 70E, Standard for Electrical Safety Requirements for Employee Workplaces covers the standards for PPE.)

Cost of an electric arc accident
The monetary cost of an electric arc accident can run into the hundreds of thousands of dollars. Damage to equipment and facility, lost production time, increased insurance expense, medical bills, worker’s compensation, and legal costs can all be the result of one electric arc accident.

Questions?
Talk to your supervisor if you have any questions or concerns about working around energized electrical equipment

This information is provided by Assurance Agency https:www.assuranceagency.com