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Understanding And Protecting Against Arc Flashes

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As you maintain and repair a wide variety of electrical equipment, there are plenty of hidden dangers to look out for. One such danger involves arc flashes, a dangerous phenomenon that can easily prove fatal if you're not adequately protected against it.

Knowing how to protect yourself against arc flashes can mean the difference between life and death. The following offers a general definition of an arc flash, how they can occur and what you can do to avoid serious injury as you work on electrical construction.

Defining Arc Flash

An arc flash is essentially a short circuit that discharges tremendous amounts of electricity between two conductors or between a conductor and ground. A typical arc flash sends a powerful, high-amperage current through the air, where it creates enough energy, heat and pressure to seriously injure or even kill a person.

It's not just the electric arc itself that causes severe or even fatal injury.

During an arc flash, temperatures can reach or even exceed 35,000 degrees Fahrenheit – enough to quickly render copper and other conductive metals into plasma. The resultant molten fragments can easily produce second-degree burns and cause non-protective clothing to ignite upon contact.

The accompanying release of blast energy is also enough to propel you several feet from the source of the explosion. This can be a dangerous problem in high-rise areas, where victims can be blown off of ledges or platforms during an arc flash.

How Arc Flashes Occur

There are several instances where an arc flash can occur. These include instances where:

  • There's a break or gap in the conductor's insulation
  • Impurities such as dust and corrosion collect on a conductor's surface
  • A tool is accidentally dropped, causing a spark leading to arc flash ignition
  • Bringing a conductive object in close contact to a high-amp source
  • Using the wrong test equipment and/or the wrong testing procedures

Arc flashes are most likely to occur when racking and un-racking high-voltage equipment such as circuit breakers. Unless the fault that triggered the circuit breaker is dealt with, it's possible to create an arc flash once power is restored through the breaker in question.

Safety Procedures for Preventing Arc Flashes

Believe it or not, arc flashes aren't the leading cause of fatalities among electrical workers. Nevertheless, they remain a potentially deadly phenomenon that should be avoided at all costs.

Following safe work practices is absolutely essential for controlling and minimizing electrical hazards:

  • Heed all warning labels and signs.
  • Exercise and respect lock-out/tag-out (LOTO) practices and procedures.
  • Never perform functions you haven't been properly trained to do, especially on your own.
  • Always have an understanding of how to de-energize, isolate and handle electrical equipment, making sure to follow specific guidelines on said equipment.
  • Always stand to one side while switching breakers to avoid taking the full brunt of a dangerous arc flash.

The Role of PPE

Flame-resistant personal protective equipment (PPE) can be a life-saver when it comes to dealing with electrical equipment, especially that with the potential to create an arc flash. Wearing PPE minimizes your chances of suffering severe burns due to clothing fires sparked by molten metal or flash fire.

You should always wear the correct PPE that offers maximum protection against arc flashing. The National Fire Protection Association (NFPA) 70E guideline addresses appropriate PPE selection for a variety of conditions. Keep in mind that while PPE protects against second-degree burns, it provides little protection against the pressure blasts that could accompany a potential arc flash.

The likelihood of an arc flash can be mitigated through the proper safety and protection techniques. Understanding how to correctly deal with such a phenomenon will help you remain productive and safe.