Arc-Flash: Worth a Hazard Assessment

Walter Resendes

Walter Resendes

Arc-Flash: Worth a Hazard Assessment

The dictionary describes an electric arc as “a luminous bridge formed in a gap between two electrodes”.

 It sounds a little like the meeting of Harry Potter and He-Who-Must-Not-Be-Named’s wands, and doesn’t look entirely different, really.

Powerful as those wizards may be, an electrical arc holds a great deal more  potential for danger. If a short circuit condition passes through an electrical “arc gap,” the resulting arc flash, or “flashover” can be catastrophic, expelling large amounts of deadly energy, ionizing the air, and creating temperatures that can reach as high as 35,000 degrees Fahrenheit.

That’s hotter than the surface of the sun, friends.

Aside from the dangers that are obvious to the layperson, here’s how GE describes the aftermath of an arc flash:

The heat can also result in ignition of any nearby combustible materials… liquefy or vaporize metal parts in the vicinity…This material rapidly expands in volume as it changes state from a solid to vapor, resulting in explosive pressure and sound waves. The pressure wave can knock workers off balance or off ladders and even throw them across the room…The sound blast can cause eardrums to rupture…Molten metal can be sprayed by the blast…Solid metal debris and other loose objects, such as tools, can be turned into deadly projectiles…The bright flash from the event can result in temporary or permanent blindness. All of these will most likely result in equipment damage as well as personnel injury, and possibly death.

Serious, serious stuff. That said, if you spend time operating, supervising, or just being around industrial or commercial electrical equipment, you need to know where there is potential for an arc flash to occur, how to prevent an arc flash, and how best to minimize the damage should an arc flash incident take place.

So, what causes an arc flash?

  • accidental contact with the electrical arc
  • equipment that is underrated for the available short circuit current
  • contamination or tracking that interrupts insulated surfaces
  • deterioration or corrosion of equipment and, or parts

And that’s not all of the possible causes.

In industrial facilities dealing with high or even low voltage equipment, though, it’s essential, and in fact, required by the Occupational Safety and Health Administration (OSHA) and the National Fire Protection Association (NFPA) to have your facility professionally assessed for arc flash hazards. An Arc-Flash Hazard Assessment determines the degree to which a worker may be exposed to potential Arc-Flash Hazards and what kind of Personal Protective Equipment (PPE) is required to protect workers from the heat, light, and blast associated with an Arc-Flash accident.

If you’ve gotten an Arc-Flash Hazard Assessment done, you know they really go into detail.

Your pros will check

  • Fuses and circuit breakers: Manufacturer, type, amp rating, short circuit rating, time delay
  • Panel & Switchboards: Manufacturer, type, amp rating, short circuit rating, time delay
  • Primary and Secondary Transformers: size, impedance, fusing, short circuit available, time delay
  • Disconnects: size, short circuit ratings, fusing, time delay
  • Bus Ducts: size, short circuit rating and all buckets or disconnects on the duct, fusing, length
  • Equipment Panels: All exposures that are on the end of the line fed from the above panels/switchboards. Short circuit ratings, fusing/circuit breakers, time delay in the panel.
  • Primary Electrical Equipment (facility owned): wiring, fusing, switchgear.

And if you think that’s thorough…there’s more. Expert arc-flash assessors will:

  1. Perform a system Short Circuit Analysis and Overcurrent Protection Coordination
  2. Interrupt Rating Analysis
  3. Calculate Arc Flash Incident Energy at each point in system
  4. Determine if circuit breaker or fusing changes can reduce the incident energy
  5. Calculate Arc Flash Boundaries for each point in system
  6. Determine Personal Protective Equipment (PPE) for Arc Flash Incident Energy determined
  7. Label all points in the system with appropriate labels
  8. Provide safety training and information to “Qualified” personnel who work inside the Arc Flash Boundary
  9. Provide Basic Electrical Awareness training for everyone at the facility.

You’ll come out with proper labelling for your equipment and work areas, PPE standards for payrolled workers and contractors, and the training needed to provide the safest environment possible at your facility. If you know what hazards you’re dealing with, you can develop the best safety training plans, protocol, tool and clothing requirements, and ultimately, save employee lives while ensuring your company is compliant and won’t be hit with fines or, should an incident occur, lawsuits or even a shutdown.

To learn more about Arc Flash Safety compliance, or how Access Electric can help you perform an Arc Flash Study, give us a call or click here to contact us and we will be happy to help you get the process started.

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