What is an arc flash?
An arc flash is an electrical explosion caused from a short circuit or fault condition in an electrical system. When an arc flash explosion occurs, temperatures may exceed 30,000° F—for reference, the sun’s surface is only 9,000° F. The electrical energy vaporizes anything that gets in the way, including conductors, buses, electrical equipment, and even people.
Solid copper conductors, when vaporized, can expand up to 67,000 times their original size in an instant. With such a quick expansion, one can imagine the pressure generated from the blast. The results of an arc flash blast can cause fire, destroy equipment, and send parts flying everywhere, resulting in injuries. It is therefore vital that we protect against the hazards of an arc flash in our work.
How do we protect people from potential Arc Flash Hazards?
There are several different methods that can be used to reduce the hazards for personnel working on the equipment. The best method is to remove potential energy by de-energizing the equipment when work is going to be performed. The equipment needs to be verified as de-energized prior to working on it by someone wearing the proper Personal Protection Equipment (PPE). All equipment should be treated as energized until verified otherwise. However, there are situations where the equipment cannot be de-energized or where work is required to be performed on energized equipment.
When personnel are going to be working on any energized equipment, proper PPE must be used. To figure out what kind of PPE to use, a hazard analysis (or arc flash analysis) must be performed to determine the arc ratings of the equipment. Once an arc flash report is provided, the appropriate arc flash-rated PPE can be chosen. The PPE must exceed the calculated risk and is based on arc flash analysis.
An arc flash analysis should be updated whenever a major modification occurs, such as a new transformer, motor, breaker settings, or new motor control center among other items. At a minimum, an arc flash analysis should be completed every five years because the utility’s available fault current supplying the facility may change. This changes the arc flash hazards and requires an evaluation of the system. To reduce cost and speed up the process of performing the study, make sure to keep the existing system analysis and request the software file of the new analysis.
An arc flash explosion can be extremely costly in terms of damage to equipment, not to mention human life. It is crucial that we understand how to protect everyone involved so we can continue to provide safe, effective solutions to clients.
