Worker protected from arc flash by energy shield.

Arc Flash: The Silent Workplace Hazard and How to Tame It

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Soraya Malik in Tech & Innovation May 2025 • 5 min read.

"Protecting your personnel and equipment with cutting-edge arc flash mitigation techniques in low-voltage environments"


In the realm of workplace safety, electrical hazards loom large, with arc flash incidents being a particularly grave concern. Arc flash is a dangerous electrical explosion that can occur when a fault in an electrical system creates an arc of intense heat and energy. These events can result in severe burns, equipment damage, and even fatalities. As awareness of these dangers grows, so does the demand for effective mitigation strategies.

The National Electric Code (NEC) has taken note of this growing concern, introducing requirements in section 240.87 to reduce clearing times of overcurrent protective devices. This focuses on systems with a continuous current rating of 1200A or higher. One of the key methods highlighted by the NEC is the use of energy-reducing arc flash mitigation systems. These systems are designed to minimize the energy released during an arc flash event, thereby reducing the potential for harm.

This article delves into the world of arc flash mitigation, exploring the innovative technologies and strategies that are revolutionizing electrical safety. We'll break down the complexities of these systems, making them accessible and understandable for a broad audience, including those who may not have a deep technical background. By the end, you'll have a clearer understanding of how to protect your personnel and equipment from the devastating effects of arc flash.

What are Energy-Reducing Active Arc Flash Mitigation Systems?

Worker protected from arc flash by energy shield.

Traditional methods for mitigating arc flash hazards often rely on the clearing time of upstream overcurrent protective devices, such as circuit breakers. However, these devices have a limiting factor: their clearing time. Power circuit breakers, for instance, can take as long as 4 cycles (approximately 67 milliseconds) to clear a fault. In high-fault current systems, this delay can be too long to adequately reduce incident energy. High incident energy events often lead to equipment damage and can cause burn injuries requiring personal protective equipment (PPE).

Arc flash relays represent a step forward, sending a trip signal to the upstream circuit breaker to expedite the clearing process. However, the most advanced systems circumvent the limitations of traditional circuit breakers altogether. These innovative systems, as defined by the UL Standard for Arcing Fault Quenching Equipment, create a lower impedance current path to transfer the arcing fault to a controlled compartment. This rapid transfer significantly reduces the duration of the arc flash, minimizing incident energy.

  • Zone-Selective Interlocking
  • Differential Relaying
  • Energy-Reducing Maintenance Switching with Local Status Indicator
  • Energy-Reducing Active Arc Flash Mitigation System
  • An instantaneous trip setting that is less than the available arcing current
  • An instantaneous override that is less than the available arcing current
  • An approved equivalent means
These arc quenching systems come in two primary flavors: those that apply a bolted fault to create a low-impedance path and those that create a controlled arcing fault. Bolted fault systems, while effective, can subject upstream equipment to maximum peak fault currents, potentially causing damage. The latest systems generate a controlled arcing fault path, offering a lower impedance than the original arcing fault but a higher impedance than a bolted fault. This approach still transfers the arc to a controlled compartment but reduces stress on upstream equipment while maintaining effective incident energy reduction. These cutting-edge systems are called current limiting arc quenching devices.

The Future of Arc Flash Safety

As industries continue to prioritize personnel safety and equipment protection, the demand for effective arc flash mitigation strategies will only increase. Current limiting arc quenching devices represent a significant leap forward in arc flash safety, offering superior personnel protection, advanced equipment protection, and reduced downtime. By understanding the principles behind these technologies and implementing them in your facilities, you can create a safer and more productive work environment.

Everything You Need To Know

1

What exactly is an arc flash, and why should I be concerned about it?

An arc flash is a dangerous electrical explosion caused by a fault in an electrical system, producing intense heat and energy. The significance of understanding arc flash lies in its potential to cause severe burns, equipment damage, and even fatalities. Effective mitigation strategies are crucial to protect personnel and equipment in industrial settings. Without these strategies the clearing times on overcurrent protective devices may be too long and not adequately reduce incident energy.

2

What are energy-reducing arc flash mitigation systems, and why are they important?

Energy-reducing arc flash mitigation systems are designed to minimize the energy released during an arc flash event, reducing the potential for harm. These systems are vital because traditional methods, which rely on the clearing time of upstream overcurrent protective devices like circuit breakers, can be too slow, especially in high-fault current systems. This is why the NEC has introduced requirements in section 240.87 to reduce clearing times of overcurrent protective devices.

3

How do arc flash relays and advanced mitigation systems differ in protecting against arc flash?

Arc flash relays expedite the clearing process by sending a trip signal to the upstream circuit breaker, but the most advanced mitigation systems bypass traditional circuit breakers altogether. These systems, defined by the UL Standard for Arcing Fault Quenching Equipment, create a lower impedance current path to transfer the arcing fault to a controlled compartment. This rapid transfer significantly reduces the duration of the arc flash and is more effective than traditional relays.

4

What are current limiting arc quenching devices, and how do they improve arc flash safety compared to other methods?

Current limiting arc quenching devices are cutting-edge systems that generate a controlled arcing fault path, which offers a lower impedance than the original arcing fault but a higher impedance than a bolted fault. This approach transfers the arc to a controlled compartment while reducing stress on upstream equipment, maintaining effective incident energy reduction. Bolted fault systems can subject upstream equipment to maximum peak fault currents, potentially causing damage, making current limiting arc quenching devices a safer and more effective alternative.

5

Besides the devices themselves, are there other strategies that can help mitigate arc flash hazards in the workplace?

Several strategies can mitigate arc flash hazards, including Zone-Selective Interlocking, Differential Relaying, Energy-Reducing Maintenance Switching with Local Status Indicator, Energy-Reducing Active Arc Flash Mitigation System, instantaneous trip settings, and approved equivalent means. Implementing these technologies can significantly reduce the risk of arc flash incidents, creating a safer and more productive work environment. These strategies allow for the transfer of arcing fault to controlled compartment, reducing the duration of the arc flash.

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