An arc flash is a dangerous phenomenon that occurs when there is an electrical fault between live conductors or between a conductor and the ground. In such cases, the current deviates from its normal path, traveling through the air, and may strike another conductor or the ground. The radiant energy released by an arc flash is capable of causing severe injuries or fatalities, even at distances of up to 20 feet. The extreme pressure of the blast can throw workers against walls, resulting in significant harm. Arc flash incidents are frequent in India, as indicated by hospitalization records. A single simple mistake can lead to catastrophic consequences.
In the United States, the Bureau of Labor Statistics reports that over the past decade, there have been 2,000 fatalities and more than 24,000 non-fatal electrical injuries due to arc flashes. The severity of these injuries depends on various factors, including:
- Distance from the hazard
- Heat exposure
- Circuit tripping time
Typical Effects of an Arc Flash:
- Temperatures exceeding 35,000°F.
- Molten metal objects flying through the air, injuring anyone in the blast’s path.
- Severe burns, as ordinary clothing can catch fire and stick to the skin.
- Rapid fire spread throughout a building or installation.
- High-pressure blasts reaching over 2,000 psi, creating powerful shockwaves.
- Dangerous noise levels exceeding 140 dB, comparable to the sound of a gunshot.
Arc Flash Risk Management
Electrical maintenance, diagnostics, and testing tasks often require workers to be near or work on energized electrical circuits. Therefore, calculating the arc flash distance at locations where voltages exceed 50 volts is essential for safety. There are two primary methods for determining the appropriate protection and Personal Protective Equipment (PPE) requirements: engineering analysis and the table method.
Best Practices for Complying with NFPA 70E Standards:
- Preventive Maintenance
- Risk Assessment
- Labeling and Hazard Communication Plans
- Design and Method Reviews
- Accurate Single-Line Diagrams
- Short Circuit and Coordination Studies
- Electrical Safety Program Review/Development
- Arc Flash Training Program and PPE Plan Development
- Documentation
- Periodic Reviews
Managing High-Risk Electrical Systems
Working with electricity poses inherent risks, as it is an invisible yet powerful energy source. Electrical incidents can occur suddenly, with anyone nearby at risk of injury. Employers must prioritize maintaining their systems and, where possible, de-energizing electrical systems to a zero-potential state during maintenance. However, if working on live systems is unavoidable, employers should plan ahead to ensure the appropriate level of protection and safe work procedures are in place. International organizations like OSHA and NFPA are proactive in providing and enforcing standards to mitigate these risks and safeguard workers.
For more information on electrical safety and other Environmental, Health, and Safety (EHS) topics, refer to our publication Core EHS Magazine here.
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