What are the main causes of an Arc Flash?

Electrical Switch Could Generate Arc Flash

This is the fourth post in a six-part “Fundamentals of Arc Flash” series. Check back regularly to read new posts offering valuable information on topics such as arc flash causes and characteristics, ratings, and analysis.

If you work with energized electrical equipment, you’ve probably heard of an arc flash. And, with some estimates showing nearly 30,000 incidents of arc flash per year, you may have even seen this deadly hazard on the job. While wearing arc-rated flame resistant (FR) clothing is an integral part of protecting yourself against arc flash, knowing the main causes of the phenomenon and taking preventative measures to lower the risk of occurrence are important as well. Watch Scott Margolin, recognized Subject Matter Expert and Vice President of Technical at Tyndale, outline common causes of arc flash below, and read on to learn more:

What causes an arc flash?
Ideally, a circuit controls the amount of electrical current that flows through the circuit, maintaining the appropriate voltage and resistance required to keep the flow contained. Arc flash occurs when electrical current becomes uncontrolled, and passes through an air gap between conductors in an attempt to “jump” from one conductor to another. This results in a release of electrical energy that ionizes the surrounding air, generating an enormous amount of light, heat, and sound.

Okay, but what causes the electrical current to become uncontrolled?
Human error is the most common cause of arc flash. After a worker has performed the same task over and over without incident, they may bypass a maintenance step or develop a procedural workaround to save time. These habits can lead to mistakes, like dropping a conductive item (like a screw or bolt) into the equipment enclosure. In that case, the dropped screw could interrupt the flow of electrical current and cause the current to jump, leading to an arc flash. In another example of human error, a worker may elect to use an uninsulated tool to perform a simple task, like making a routine adjustment to a control panel. However, if the worker fumbles with the uninsulated tool and it makes contact with the ground, electrical current could attempt to flow to the conductive tool and create an arc flash.

Environmental factors like buildup of dust and debris on or around the surface of the conductor can create an environment ripe for arc flash. With this type of buildup, the flow of electrical current can be interrupted and drawn to an outside conductor, creating a jump and subsequent arc flash.

Arc flash can also be brought on by an equipment failure due to use of faulty parts, corroding insulation, or normal wear and tear. Because electrical equipment parts are rated for certain levels of current, using a part that is not appropriately rated for its application can lead to an arc flash situation. If insulated portions of the equipment begin to corrode (sometimes due to wear and tear, and sometimes due to improper installation), this can expose conductive surfaces and cause an arc flash.

What preventative steps can be taken to reduce the risk of arc flash?
Although working on de-energized equipment is the only way to ensure no electrical current is present, there are situations where interacting with energized equipment is unavoidable. In these cases, maintaining focus while performing even the most routine of tasks is of the utmost importance. Equally important is performing regular workplace housekeeping in and around energized equipment, and taking the time to remove dust and debris before performing work if necessary. As always, because there are some contributors to arc flash that are invisible to the naked eye, such as faulty or incorrectly installed parts, it is important to always wear arc-rated FR clothing as a last line of defense while performing energized work.

Want to learn more? Browse our blog posts for more helpful information about protecting workers with FR and the answers to other frequently-asked questions. Plus, find out about FR product options and how our managed program can help you maximize compliance and protection while enhancing service and satisfaction.

Have additional questions? Schedule a complimentary 15-minute technical session with Scott Margolin, Tyndale’s Vice President of Technical. Simply complete the form below and Scott will contact you at a mutually agreeable time to speak one-on-one.

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