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Arc flash, also known as flashover or arc fault, is a risk for any workplace that has energized equipment. This uncontrolled electrical discharge can cause serious injury or even death for any workers in the vicinity. Read on to learn more about arc flash danger around generators and how to protect your workers.
What Is Arc Flash?
All electrical equipment is designed so electricity will follow a particular path. But sometimes, that electricity follows an unexpected path. It may jump to another conductor, or it may move to ground. An incident like this is called an arc flash.
An arc flash’s massive electrical discharge can create a dramatic and rapid increase in temperature, as much as 35,000 degrees Fahrenheit. That can create fires and serious burns in workers, with non- fire-resistant clothing melting onto skin.
When the discharge is serious enough to vaporize the conductors, arc flash can create a supersonic shockwave called an arc blast. This explosion can be as loud as a gunshot (140 dB), with pressure upward of 2,000 pounds per square foot. This blast can send objects flying, including molten metal created by the initial arc flash. As you might imagine, arc flash can cause serious injury or death, and a worker in an arc flash accident may never fully regain her quality of life.
Protecting Your Workers
A number of situations can cause an arc flash or can increase the risk of one at the automatic transfer switch. Arc flash causes include:
- dropping tools,
- accidentally touching an energized device,
- condensation,
- dust in the air,
- corrosion or material failure, or
- faulty installation.
Experts have identified several ways to protect workers from arc flash danger. These are vital for anyone working with electricity to understand.
De-energize the circuit. This is the only 100-percent reliable way to prevent arc flash, and it should be standard practice to only work on de-energized circuits whenever possible. If the circuit must be “hot,” workers should follow all other listed safety procedures. One way of making electrified circuits safer is by installing arc fault circuit interrupters (AFCIs) or ground fault circuit interrupters (GFCIs). These are automatic circuit breakers that de-energize electrified circuits when they detect unusual energy flow.
Follow all safe work practices. Anyone working on an energized circuit should receive proper training. Written safety programs and on-the-job briefings are ideal, and many organizations also request an Energized Electrical Work Permit (EEWP) from all employees working on the electrified circuit. This training should include instructions on reading arc flash warning labels, differentiating between live and de-energized equipment, determining nominal voltage and determining clearance distances.
Use insulated safety equipment, including gloves, mats and blankets.
Barricade the approach boundaries, and restrict access to certified personnel. The National Fire Protection Association (NFPA) has designated certain approach boundaries surrounding an exposed, energized part. The innermost boundary is the prohibited approach boundary, and entering this zone is considered equivalent to touching the live part. The restricted and limited approach boundaries describe areas in which there’s a steadily decreasing risk of arc flash. The flash protection boundary is the outermost boundary; anyone from this point onward is at risk of a curable second-degree burn.
Be aware of circuits’ energy levels. For instance, if a generator feeds an automatic transfer switch (ATS), the ATS and all other equipment downstream often has higher energy levels than it would if fed by normal mains electricity. This can increase the risk of arc flash, and necessitates greater safety precautions.
Arc flash is a serious risk to workers’ safety, but with a little care you can protect your employees. And if you have any questions about your generator’s arc flash risk, or if you need it serviced, don’t forget to reach out to CD & Power for help: the time you take could save your employees’ lives.
