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The term “arc flash” is used to describe low impedance connections in an electrical system, which allows movement of unwanted electric discharge through the air from one voltage phase to another, or to ground. This leads to a rapid rise in temperature and pressure in the air between electrical conductors, causing an explosion known as an arc blast.
Arc blasts and the resulting heat can lead to fires, pressure waves and flying shrapnel that result in serious damage to life and property. These explosions typically occur without any warning, destroy electrical equipment completely and lead to severe injury or death of personnel present within the boundary of the arc flash.
What Are the Main Causes of Arc Flash?
Arc flash occurs when several electrical conductors are placed close to each other, with significant fault currents flowing through them. In this situation, ionization of the air can take place as a result of various factors – such as differences in potential – which leads to a low resistance path and allows current to flow through the air gap between conductors.
Many people assume that low voltage equipment is safe from arc flash, but arc flash hazard levels may be higher at low voltages, due to the high fault currents. Most incidents that occur in low voltage systems are caused by human error, e.g. a tool slipping while a technician works on electrical equipment.
Arc flash can also be caused due to:
- Carelessness or accidents, e.g. touching the wrong surface with a test probe
- Improper tools, installation and work techniques
- Lack of electrical safety awareness and training
- Use of damaged electrical materials/equipment
- Obstruction in disconnect panels
- Insulation damage, gaps or wear and tear
- Dust, debris and corrosion on electrical conductors
- Improper preventative maintenance for circuit breakers and switches
- Exposed live parts, loose connections or corrosion
- Static electricity or high voltage cables
- Exposure of electrical equipment to water or other liquids
What Are the Best Ways to Avoid Arc Flash?
With the right training, safety procedures and equipment, it’s possible to minimize the risk of arc flash. Here are 5 important precautions you should take:
- De-Energize Equipment and Remove Personnel
It’s critical to eliminate the potential hazard as far as possible. Avoid working on energized electrical equipment, and take extra care while testing to ensure it has been de-energized or while re-energizing it.
Use remote racking technology to operate circuit breakers from outside the arc flash boundary instead of allowing personnel to be put at risk of injury or death.
- Study the Hazard and Use Low-Risk Technology
Collect data about your facility’s power distribution system, and conduct short circuit and protective device coordination studies to identify arc flash hazard categories for electrical equipment, as well as how to reduce them.
Also, look into technologies such as remote racking equipment and arc limiting fuses that help keep personnel as well as property safe.
- Redesign Electrical Systems and Controls
Determine the correct level of PPE – personal protective equipment – required as per the flash hazard category, and ensure that personnel are properly equipped. Redesign your equipment and processes to maximize engineering controls that help prevent and lessen risk.
Adjust settings for circuit breakers and energy distribution systems where needed, and substitute high-risk electrical equipment with devices that reduce incident energy.
- Improve Safety Training and Risk Awareness
In addition to being mandated by regulatory authorities like OSHA, proper safety training also ensures that your personnel understand the consequences of being careless and follow proper safety procedures at all times.
Not only could this help keep them safe in the event of an arc flash, but also help them understand how to minimize the risk.
- Create and Implement a Strict Safety Program
Identify the risks, boundaries and suitable PPE for electrical safety through arc flash hazard studies. Make sure that proper electrical regulations and work processes are documented, shared with all involved personnel, and strictly enforced.
Also create a preventive maintenance program for electrical materials/equipment, and ensure that only qualified and fully trained personnel equipped with the proper tools and PPE are allowed to work on electrical systems.