An Arc Flash Study is the term sometimes used to describe an incident energy study. It is a calculation of the thermal heat during an arcing short circuit in an electrical distribution system. A competent engineer will evaluate and understand the worst-case hazard that a worker might be exposed to if an arc flash event occurred. When a hazardous arc flash situation has been identified, control measures shall be implemented if justified energized work is intended to continue.
What is an Arc Flash?
OSHA (the Occupational Safety and Health Administration, U.S. Department of Labor) defines an arc flash as “A phenomenon where a flashover of electric current leaves its intended path and travels through the air from one conductor to another, or the ground. The results are often violent, and when a human is near the arc flash, serious injury and even death can occur.”
What causes an Arc Flash?
A spark-induced arc flash, or electrical explosion, is a form of electric discharge that occurs when electricity passes through the air to earth or another voltage phase in an electrical system.
An arc flash event might be caused by a variety of factors, including:
- Incorrect switchgear operation and failure
- Dust, vermin, or process material in the switching gear
- Inspection of access panels (hinged and non-hinged)
- Linkage failure of operating handles and switchgear
- Loose connections disturbed during the replacement of the access panel
- Fasteners have dropped
- Test equipment that has been mistreated or is faulty
- Slip or inadvertent movement when using test probes
- Working near live conductive parts and live working
- Tools and equipment are not labeled correctly
- Unfamiliarity with the site/equipment and incorrect documentation
How do we measure the risk posed by Arc Flash?
The first step is to evaluate the hazard. We must know the worst-case incident energy so that an adequate arc flash risk assessment can be implemented for each piece of equipment on the electrical system. The hazard is determined by measuring the incident energy level for each piece of equipment. Incident energy is the amount of thermal energy imparted on a surface, at a specific distance from the source, during an electric arc event.
It may be measured in a variety of units, but it is most often reported in calories per centimeter2 (Cal/cm2) because arc flash protective gear (PPE) is usually rated in Cal/cm2. Conditions of Maintenance shall also be noted and documented in risk assessment. Breakers shall be tested, proven adequate for the short circuit energy and the clearing times are accurate per the designed intent.
What do you get with an Incident Energy Study?
Performing a comprehensive incident energy study allows you to understand the risk at the different electrical locations in your facility where each electrical system poses a hazard. You then establish an electrical safety program ( rules) requiring workers to be qualified and to protect themselves and others from these hazards. Sometimes this protection is to wear the necessary personal protection equipment (PPE) in those areas. Your business compliance with OSHA rules with eliminate future finds from negligence. After completing the study, it will prove to be an important mode of communication to show the value to your workers.
How can Bowtie Engineering help?
If you want further information or assistance solving the complexity of your electrical safety program, please complete our form or contact us via phone or email. We know how important this is to you, and we want to build a long term relationship with your people accountable for implementing. This is step one in building trust and loyalty. We are happy to show the value, provide quoting and training for you and others in your organization.