An Arc Flash or an Electric Arc is the rapid and dangerous release of energy due to an electrical arcing fault. It happens in a fraction of a second – even faster that you can blink your eye and can have devastating consequences for anyone exposed.
TYPES OF ARC FLASH
Confined Flash
This happens when an Arc Flash occurs in a distribution box or a motor control centre. The flash is contained on all sides except the front opening of the box. All of the focused energy escapes through the only opening onto the hands and face of the person working on the box.
Open Flash
Takes place when an Arc Flash occurs in an open space with the energy escaping 360° in all directions. The molten metal can ignite the PC and PPE of the worker.
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
ARC FLASH INTENSITY
The intensity of the Arc Flash is influenced not only by the voltage. An Arc Flash will contain the release of thermal energy, acoustical energy, pressure wave and debris.
The variables that affect the size and energy of an electric Arc Flash are:
- Voltage (safety issue where greater than 220 Volts)
- Amperage
- Arc Gap
- Closure Time
- Distance away from the arc
- 3 Phase v Single Phase
- Confined Space
ARC FLASH INJURIES
The consequences of an Arc Flash can be devastating depending on the intensity of the Arc Flash, the proximity of the individual to the source of the arc and the PPE used if any.
Injuries can include:
- 3rd degree (irreversible) burns caused by extreme heat and molten splatter
- Loss of sight due to electromagnetic radiation
- Internal burns and intoxication due to inhalation of hot toxic gases
- Permanent hearing damage due to explosion bang
- Other physical trauma caused by the explosion (blast pressure and flying debris)
- Death
PROTECTING PERSONNEL
There are many methods of protecting personnel from Arc Flash hazards. This can include personnel wearing Arc Flash PPE or modifying the design and configuration of electrical equipment. The best way to remove the hazards of an Arc Flash is to de-energize electrical equipment when interacting with it, however de-energizing electrical equipment is in and of itself an Arc Flash hazard.
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:
1. 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.
2. 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.
3. 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.
4. 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.
5. 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.
Source:
