Transcript
There are few hazards more dangerous than arc flashes and arc blasts. These events are often confused or lumped together but are two separate phenomena. Understanding the difference could decide between a near-miss and a life-altering injury. Both are serious risks that demand different protective strategies.
What is an arc flash?
An arc flash occurs when electricity travels through the air between two conductors or from a conductor to the ground. This can happen when equipment is damaged or improperly maintained or someone accidentally contacts an energized component. The electrical energy released creates a burst of intense heat and light.
Temperatures from an arc flash can reach up to 35,000 degrees Fahrenheit. That’s hotter than the surface of the sun. This kind of thermal energy can vaporize metal, ignite clothing, and cause severe burns to anyone nearby. Injuries can also include vision damage, respiratory issues from inhaling vaporized materials, and in extreme cases, death.
Arc flashes account for around 30,000 injuries per year. It’s one of the most common and dangerous electrical events in the workplace.1
Energy Type: Thermal (heat and light)
Cause: Electrical arc fault
Injury Type: Burns, eye damage, respiratory issues
Duration: Milliseconds to a few seconds
What is an arc blast?
An arc blast is the violent pressure wave that follows an arc flash. While the flash generates heat and light, the blast is a mechanical force that can physically throw people across a room, rupture eardrums, and create secondary hazards like flying debris. The pressure from an arc blast can reach several hundred pounds per square inch, and the sound levels can exceed 160 decibels.2
The arc blast is often responsible for blunt force trauma, broken bones, concussions, and internal injuries. The combination of heat and pressure makes these incidents especially destructive in confined spaces like electrical rooms.
Energy Type: Mechanical (pressure and sound)
Cause: Result of the arc flash
Injury Type: Blunt trauma, hearing loss, concussions
Duration: Instantaneous
Common causes
Many arc flash and arc blast incident have shared root causes. These include:
- Worn or damaged insulation
- Loose or corroded electrical connections
- Improperly installed components
- Human error, such as dropped tools or accidental contact with energized parts
- Voltage spikes or transients
Industry estimates suggest that between five and ten arc fault incidents occur every day in the United States.3 These are not rare events. They happen in industrial plants, data centers, commercial buildings, and other settings where electrical systems are constantly used.
Reducing the risk
Preventing arc flash and arc blast incidents starts with understanding the hazards. While OSHA does not mandate a specific schedule, NFPA 70E recommends reviewing arc flash risk assessments at least every five years or whenever significant changes are made to the electrical system. These assessments help determine how much thermal energy could be released during an event and guide the safety strategies needed to mitigate it.4
Maintenance is equally important. NFPA 70E also advises that electrical systems be maintained according to the manufacturer's instructions or industry consensus standards. This helps reduce the likelihood of failure that could lead to a dangerous incident.5
Other prevention strategies include:
- De-energizing circuits before performing work whenever possible
- Properly labeling electrical panels and components
- Using high-resistance grounding devices
- Wearing personal protective equipment (PPE) rated for arc flash hazards
Why it matters
An arc flash event doesn’t just injure employees. It can result in lawsuits, regulatory fines, downtime, and equipment replacement costs. Some estimates put the total financial impact between 12 and 15 million dollars per incident.6
But it’s not just about dollars. It’s also about creating a workplace where employees feel safe. Failing to understand the difference between an arc flash and an arc blast means you might not be considering the full spectrum of risk.
Preventing arc blasts and arc flashes
Arc flashes and arc blasts are related but different. The flash delivers extreme heat and light, while the blast delivers violent force. Together, they pose one of the most serious safety threats in any facility with electrical systems. The good news is that they can be managed and mitigated with awareness, training, and a solid prevention plan.
Need help identifying arc flash hazards in your facility? Contact ABM’s electrical safety team to schedule a risk assessment and build a safer, more compliant workplace.
Sources
[1]. https://www.safetyvideos.com/arc-flash-hazard-analysis
[2] https://www.nfpa.org/News-and-Research/Data-research-and-tools/Electrical/Fatal-electrical-injuries-at-work
[3] https://www.osha.gov/sites/default/files/publications/OSHA4472.pdf
[4] https://www.bradyid.com/resources/arc-flash-risk-assessment
[5] https://www.nfpa.org/product/nfpa-70e-standard/p0070ecode
[6] https://www.esfi.org/resource/workplace-safety-in-the-u-s-electrical-contractor-industry-503
