Question: What is an Arc Flash Event?
Answer: An Arc Flash Event is where large currents caused by extremely low abnormal impedances, travel thru an air gap as an arc. The resultant is extremely high temperatures, vaporized metals and an explosive expansion of the gases released during the arcing event. An event of this sort can cause extensive damage of equipment and facilities, critical injury and even death.
Question: Why should a Company and its Employees be aware of an Arc Flash Hazard?
Answer: Arc Flash hazard rules are enforced by OSHA and they use the National Fire Protection Association’s 70E Standard for Electrical Safety in the Workplace. Failure to comply can result in large fines and citations. NFPA 70E and the 2017 National Electrical Code (NEC) require labels with maximum available arc flash incident energies and arc flash boundary distances on all enclosures containing more than 50 volts and those that may be opened while the system is energized. Companies are required to assist employees through training to identify and recognize the hazard and to understand its magnitude. OSHA outlines necessary safety-related work practices and training requirements for employees.
Question: What is an Arc Flash Study?
Answer: An Arc Flash Study evaluates all the parameters of the power distribution system. It then calculates – based on set protective devices, transformer sizes and other characteristics – and estimates the maximum amount of energy in the enclosure for an Arc Flash event. It also predicts the estimated distance from the front of the enclosure where a person with no Personal Protective Equipment (PPE) will receive a second degree burn. An Arc Flash Study should also indicate potential methods for reducing arc flash energies.
Question: Who should perform the Arc Flash Study?
Answer: The authority having jurisdiction (AHJ) and the state engineering boards have determined that Arc Flash Studies involve Electrical Engineering Calculations that directly impact life safety. Therefore, they consider only qualified Electrical Engineers licensed in that state as being qualified to perform these studies. Many are issuing injunctions against persons that are not licensed and performing this work. Georgia, Indiana, Kentucky, Ohio and West Virginia have confirmed this to Process Plus.
Question: What are the main results of an Arc Flash Study?
Answer: The study should contain the following minimum components:
- Single Line Diagrams of the system model
- General description of the power system
- General results output
- Recommendations on how to reduce Arc Flash Energies
- Arc Flash Labels for all enclosures containing more than 50 volts that might be entered while energized. This would include control panels on packaged systems where 480 volts might be present and motor controllers are potentially located at. NOTE: NOT ALL ARC FLASH STUDIES CONSIDER GOING TO THE CONTROL PANELS. PROCESS PLUS BELIEVES THAT THIS IS A MUST TO MEET THE CRITERIA AND THE INTENT OF NFPA 70E, OSHA, AND THE PROFESSIONAL ENGINEERING CODE OF ETHICS TO PROTECT THE HEALTH AND SAFETY OF THE PUBLIC.
Question: How Often Should an Arc Flash Study be revised?
Answer: The Institute of Electronic and Electrical Engineers (IEEE) which writes the standard for Arc Flash calculations recommends a study be revised when changes are made to the system or when the electric utility makes changes or improvements to their service. In any case, they recommend that a study be revised at least every five years.
Question: What should a Company need after an Arc Flash Study is done?
Answer: In addition to the Arc Flash Study and the labels being affixed to the enclosures, a company must execute training every three years for persons exposed to the hazards. The training is to be documented in the employee’s personnel file. Also, the company will provide required PPE to the employee. Finally, it is highly recommended that a company have a written safety program for electrical safety and the employees should be trained on this and basic first aid and CPR technics.
If you are interested in learning more about arc flash studies and the services we offer, please contact John Koehler.
Author: Adam Ward, P.E., SM-IEEE
