Arc Flash: What Every Employer Needs to Know Before Work Begins

Arc flash is one of the most severe electrical hazards in the workplace — and one of the most misunderstood. While many employers focus on shock hazards when it comes to electrical safety, arc flash can cause far more devastating injuries in a fraction of a second. The intense heat, pressure, and light released during an arc flash event can kill or permanently injure a worker before they have any chance to react.

This post breaks down what arc flash is, why it happens, where employers most often overlook the risk, and what practical steps you can take to protect your workers and your operation.

Here's what you'll learn:

• What arc flash is and how it differs from electrical shock

• The most common causes and contributing factors

• Where arc flash exposure is often missed on jobsites and in facilities

• Prevention strategies that actually work in the field

What Is Arc Flash — and Why Is It Different From Electrical Shock?

Most people understand that touching a live wire can cause a shock. Arc flash is a different kind of hazard entirely. It occurs when electrical current travels through the air between conductors or from a conductor to ground, creating an explosive release of energy.

That release happens fast — often in milliseconds — but the consequences are extreme. Temperatures at the arc can reach 35,000°F, roughly four times the surface temperature of the sun. The event also generates a pressure wave, molten metal, and intense ultraviolet and infrared light. A worker doesn't need to be touching anything for an arc flash to cause severe burns, blindness, hearing damage, or fatal injuries.

This distinction matters because it changes how you approach risk. Electrical shock can often be avoided by keeping your distance or using insulated tools. Arc flash can injure workers from several feet away without any direct contact at all.

Why Arc Flash Happens: Common Contributing Factors

Arc flash incidents don't occur randomly. They're almost always the result of a specific set of conditions that were allowed to exist — often without anyone realizing the exposure was there.

The most common contributing factors include:

• Improperly maintained equipment — Dust, corrosion, worn insulation, and loose connections degrade equipment over time and increase arc flash risk significantly

• Working on or near energized equipment — The most direct exposure. Any work performed without de-energizing and verifying absence of voltage creates real risk

• Accidental contact with energized parts — Dropped tools, misidentified conductors, or switching errors can initiate an arc

• Using the wrong tools — Non-rated tools or equipment that isn't appropriate for the voltage level present

• Inadequate clearances — Working in tight spaces where accidental contact with live parts is more likely

• Lack of current-limiting overcurrent protection — Without properly rated protective devices, an arc has more energy and causes greater damage before the circuit opens

Understanding these contributing factors helps you see arc flash not as a random event, but as a predictable outcome of specific conditions that can be controlled.

Where Employers Most Often Miss the Exposure

One of the biggest challenges with arc flash is that the risk often exists in places that don't look dangerous at first glance. Here's where employers routinely underestimate exposure:

Electrical panels and switchgear. Opening a panel to flip a breaker or check wiring seems routine. But if the equipment is energized and there's a fault condition present, that routine task becomes a high-energy hazard.

Motor control centers (MCCs). These are common in industrial and manufacturing settings. Racking in or out of a breaker in an MCC while the equipment is energized is one of the highest-risk tasks in industrial maintenance.

Temporary power setups on construction sites. Temporary electrical distribution isn't always given the same attention as permanent installations. Poor connections, inadequate protection, and exposure to the elements all raise arc flash risk on active construction sites.

Utility work and service entrances. Contractors working near service entrances or utility equipment often don't have full visibility into the energy levels present. This is a common point of arc flash exposure for contractors who aren't the primary electrical trade on a project.

Infrared thermography and diagnostic work. Technicians who perform inspections on energized equipment — even with panels open for testing — are exposed to arc flash hazard.

Many don't treat this as energized work even though it is.

The common thread: tasks that feel routine are often performed without the level of protection the actual hazard warrants.

Practical Prevention: What Responsible Employers Do

Preventing arc flash isn't about turning every task into a complex engineering project. It starts with building awareness and putting consistent practices in place for work involving electrical hazards.

1. Establish an Energized Electrical Work Policy

The first line of defense is a clear, written policy that defines when energized work is permitted and when it is not. OSHA and NFPA 70E both support the principle that energized work should only occur when de-energizing creates a greater hazard or is infeasible. Your policy should reflect this, and workers need to understand that de-energizing is the default, not the exception.

2. Conduct an Arc Flash Hazard Assessment

Before work begins on or near electrical equipment, someone needs to determine what the incident energy level actually is. A proper arc flash hazard assessment identifies the boundaries of exposure and the level of PPE required. This isn't optional for employers covered by OSHA 1910.132 and NFPA 70E — it's a requirement. Many employers skip this step or treat it as a one-time activity rather than an ongoing process.

3. Use the Right PPE — and Make Sure Workers Know How to Use It

Arc-rated (AR) clothing and PPE is not the same as standard flame-resistant (FR) clothing. Arc flash PPE is rated in calories per square centimeter (cal/cm²) and must be matched to the incident energy level identified in the hazard assessment. Required PPE may include:

• Arc-rated face shield or arc flash suit hood

• Arc-rated gloves (rated for the voltage level)

• Arc-rated jacket, pants, or coveralls

• Insulated tools rated for the voltage present

• Hearing protection (pressure waves cause hearing damage)

PPE is a last line of defense — not a substitute for proper planning. But when energized work must happen, proper PPE can mean the difference between a worker going home and a worker going to a burn unit.

4. Train Workers on Arc Flash Risk — Not Just General Electrical Safety

General electrical safety training doesn't cover arc flash in enough depth for workers who perform electrical work or work near energized equipment. Workers need to understand:

• What arc flash is and how it's different from shock

• What tasks create the greatest risk of arc flash exposure

• What the approach boundaries mean and why they exist

• How to select, inspect, and use arc-rated PPE

• What to do when work conditions change unexpectedly

Training should be specific to the tasks and equipment workers encounter, not generic. Refresher training matters too — habits drift over time, and complacency is one of the primary human factors in arc flash incidents.

5. Keep Equipment Properly Maintained

Deferred maintenance is one of the most common contributors to arc flash incidents. Breakers that haven't been tested, loose connections that have never been retorqued, and panels that haven't been cleaned in years are accidents waiting to happen. A preventive maintenance program for electrical equipment isn't just good practice — it directly reduces arc flash incident energy and the probability of an arc fault occurring.

6. Label Equipment with Arc Flash Hazard Information

NFPA 70E requires that electrical equipment be labeled with arc flash hazard information so that workers know what they're dealing with before they open a panel or begin work. Labels should include the incident energy level, required PPE category, and approach boundaries. If your electrical equipment isn't labeled, that's a gap that needs to be corrected.

The Cost of Getting This Wrong

Arc flash injuries are among the most severe in any industry. Burns from arc flash often require long-term hospitalization, multiple surgeries, and extended rehabilitation. Many workers never return to the same capacity. The financial cost to an employer — through workers' compensation, lost productivity, OSHA citations, and potential litigation — is significant. More importantly, the human cost is irreversible.

OSHA estimates that arc flash and related electrical incidents cause several hundred fatalities and thousands of injuries each year in the U.S. Most of those incidents were preventable with the right combination of hazard awareness, engineering controls, safe work practices, and appropriate PPE.

Start with Awareness, Build Toward Prevention

Arc flash doesn't have to be mysterious or overly complicated to address. Most of what it takes to protect workers comes down to recognizing where the risk exists, putting policies and procedures in place that reflect that risk, training workers to understand what they're dealing with, and making sure the right equipment and PPE are available and used correctly.

The employers who handle this well share one thing in common: they treat arc flash as a real operational hazard, not a theoretical one. Start there, and the rest of the prevention framework falls into place.

About Must Be Safety

Must Be Safety is a Nashville-based safety training and consulting firm serving construction, industrial, and contractor teams across Tennessee and beyond. We offer OSHA 10 and 30 Hour Construction training, safety program development, jobsite inspections, incident investigation, CPR/AED certification, equipment operator training, and workforce development solutions. Whether you need to build a safety program from the ground up or strengthen what you already have, our team brings practical, field-ready expertise to every engagement. Learn more at mustbesafety.com.