A basic overview of best practices for preventing arc flash accidents.
What is an arc flash?
For the most part, a facility’s electrical current — running through the wiring system to transformers, fuse boxes, outlets and equipment — is safe.
However, if an electrical circuit short circuits or faults, an arc of electricity can become airborne, jumping out of the power line, open fuse box, or piece of exposed live equipment. Similar to a flash of lightning, arc flashes happen unspeakably fast and produce a flare of heat hot enough to melt steel.
Arc flashes can happen for a number of reasons, including insulation failure, lack of maintenance, environmental exposure, dirt and dust, improper installation, condensation, corrosion, dropped tools, or normal wear and tear.. Dozens of incidents occur every day in the United States, resulting in equipment damage, injuries, severe burns, and even death.
We’ve visited sites in the aftermath of arc flash accidents, where we’ve had to complete our work in the presence of body bags and stricken emergency personnel. It’s a sobering reminder of how unexpected and dangerous electricity can be. But with the right safety precautions, arc flash accidents are almost entirely preventable.
Compliance goes a long way on limiting your buildings and business of huge liabilities
All companies whose employees work with electricity are mandated to comply with Occupational Safety and Health Administration (OSHA) and National Fire Protection Association (NFPA) guidelines. Specifically, NFPA 70E “helps companies and employees avoid workplace injuries and fatalities due to shock, electrocution, arc flash, and arc blast.”
Per the NFPA 70E, companies are required to perform an arc flash assessment or study to determine the risk of incidents, flash boundary, potential incident energy at the working distance, and the personal protective equipment (PPE) required.
Arc flash studies should occur on a five-year basis, but due to their complexity, experienced electrical engineers who are familiar with the particular intricacies must be the ones to perform the examination.
Proper labeling is key
NFPA 70E also requires all electrical equipment “likely to require examination, adjustment, servicing, or maintenance while energized” to be labeled with an arc flash risk identification, severity of the risk, arc flash boundary, and required PPE level.
A facility must include clear and concise warning labels to meet the industry’s safety standards. Companies that don’t have warning labels on their electrical equipment are not only failing to meet NFPA 70E requirements, but they are also leaving themselves vulnerable to workplace accidents and potentially costly lawsuits. Proper labeling reduces a company’s liability in the instance of an arc flash accident.
Adequately scheduled maintenance of equipment is key to decreasing the risk of arc flash incidents. One critically important factor for reducing arc flashes is a comprehensive switchgear maintenance program.
All switchgear maintenance programs should include infrared (IR) scans to detect loose or overloaded connections leading to arc flashes. Infrared scans work by finding areas of excess heat caused by increased resistance or defects in connections and components. IR scans allow problems to be addressed and corrected before a component fails, thus avoiding damage to the component, safety hazards, and productivity losses.
Another essential factor in switchgear maintenance is proper cleaning. Moisture, dirt, dust, and other environmental contaminants will eventually deteriorate a switchgear’s insulation, conductive materials, and protective devices. Therefore, scheduled cleaning and lubricating of switchgear will prolong the device’s operational life and reduce the chances of dangerous arc flashes.
Finally, precise torquing is an integral part of scheduled switchgear maintenance. Loose connections can lead to energy loss. More importantly, they can lead to overheating, sparking, and even arcing. Switchgears should be checked to ensure torque levels are per the manufacturer’s recommended range.