Preventing Arc Flash Injuries
The best way to prevent arc flash or to protect workers in the event of an accident is through effective training. In addition to being “qualified” under OSHA’s electrical standard, workers who may be exposed to arc flash hazards need to understand why arc flash occurs, how it can be prevented, and utilize safe work practices to prevent injury.
An arc flash is the sudden release of electrical energy through the air when a high–voltage gap exists and there is a breakdown between conductors. Common causes of arc flash include:
- Insulation failure
- Buildup of dust, impurities, and corrosion on insulating surfaces, which can provide a path for current
- Equipment failure due to the use of substandard parts, improper installation, or even normal wear and tear
- Birds, bees, and rodents snapping leads at connections
- Human error, including dropped tools, accidental contact with electrical systems, and improper work procedures
An arc flash gives off thermal radiation (heat) and bright, intense light that can cause burns. Temperatures have been recorded as high as 35,000 ˚F. High–voltage arcs can also produce considerable pressure waves by rapidly heating the air and creating a blast. This pressure burst can hit a worker with great force and send molten metal droplets from melted copper and aluminum electrical components great distances at extremely high velocities.
Arc Flash Prevention
The best way to prevent arc flash is to de-energize equipment before beginning work. Employees should be trained not to work on live equipment greater than 50 volts unless de-energizing introduces additional or increased hazards such as cutting ventilation to a hazardous location, or unless it’s impractical because of equipment design or operation limitations such as when voltage testing is required for diagnostic purposes.
Create an “electrically safe work condition” by:
- Identifying all power sources,
- Interrupting the load and disconnecting power,
- Visually verifying that a disconnect has opened the circuit,
- Locking out and tagging the circuit,
- Testing for voltage, and
- Grounding all power conductors.
When it is necessary to work on energized equipment, workers should always follow safe work practices, including assessing risks, wearing appropriate personal protective equipment (PPE), and using proper tools.
Safe Work Practices
Safe work practices can help prevent arc flash as well as protect workers in the event of an incident. Use of appropriate PPE, for example, is essential. Depending on risks, PPE could include:
- Flame-resistant clothing
- Helmet or headgear
- Face shield
- Safety glasses
- Insulating gloves
- Shoes appropriate for electrical work (no metal components)
Other precautions include:
- Obeying all warning signs and labels
- Following established work procedures
- Performing only functions employees are trained to do and have been “qualified” for according to OSHA’s electrical standard
While the focus in this article has been on employee actions, the employer has the ultimate responsibility in preventing arc flash injuries. It has the ability to provide a safety analysis of the workplace and develop engineering controls to eliminate hazards. It can engineer new or retrofitted facilities, incorporating the latest safety technology. By law, employers have the duty to provide appropriate tools, PPE, and regular maintenance of equipment and training. A commitment to training is a commitment to safety. Partnerships with equipment suppliers can bring innovative and safer technology to the workplace. Most importantly, management can demonstrate the value of safety to their employees, customers, and other stakeholders through their actions, which creates a positive safety climate where people watch out for each other.
- Arc Flash Regulations Overview (ehssafetynews.wordpress.com)
- Schneider Electric Unveils Low-Voltage Arc-Resistant Solutions To Protect Workers From Arc Flash Events (wateronline.com)
- 10 Arc Flash Prediction and Prevention Myths (datacenterknowledge.com)
Arc Flash Awareness – Centers for Disease Control and Prevention [pdf] (cdc.gov)
- ARC FLASH FACTS – Galco Industrial Electronics (galco.com)