An arc burn is an injury caused when an electrical arc, a powerful discharge of current that jumps through air between conductors, produces extreme heat that damages the skin, deeper tissues, or both. Arc temperatures in industrial settings routinely exceed several thousand degrees Celsius, enough to vaporize metal and ignite clothing within fractions of a second. What makes these burns medically distinct from a typical flame or contact burn is the combination of radiant heat, molten metal spray, and the possibility that electrical current has also traveled through the body, creating damage along paths that are invisible from the outside.
How an Arc Forms and Why It Burns
An electrical arc occurs when current bridges an air gap between two conductors. Under normal conditions, air acts as an insulator. But when voltage is high enough, or when conductors are brought close together, the air breaks down and becomes ionized, forming a superheated channel of plasma. This plasma conducts electricity and sustains itself as long as sufficient energy is flowing. The physics of thermal plasmas and electrical arcs have been modeled extensively to understand the roles of radiation, thermal conductivity, and electrical conductivity in sustaining these discharges.1IOPscience. Thermal plasma modelling
In practical terms, an arc can ignite during a short circuit, when a tool slips and bridges live components, during equipment failure, or when insulation degrades. Welding is one of the most common controlled-arc scenarios, but unintentional arc events, often called arc flash or arc blast incidents, are among the most feared hazards in electrical work. The injury isn’t just from the electricity itself. The arc radiates intense ultraviolet and infrared light, superheats the surrounding air to the point where it expands explosively, and often sprays molten metal and vaporized copper in all directions. A person caught in an arc flash can suffer burns from radiant heat alone, even without direct contact with the electrical source.
Skin Injuries and Why Severity Is Easily Misjudged
Arc burns on the skin can range from superficial redness to full-thickness destruction where the skin is charred through its entire depth. Because the heat source is so intense and the exposure can be so brief, the appearance of the wound in the first hours can be deceptive. A burn that looks red and partial-thickness at admission may reveal itself to be far deeper over the following days as damaged tissue dies. Research into burn depth assessment has long recognized this problem. Experimental work using radiant-energy arc sources on animal models whose skin closely resembles human skin confirmed that burn severity is often misjudged clinically, even by experienced practitioners.2JAMA Network. Why Burn Severity Is Often Misjudged
Part of the difficulty is that arc burns can create a patchwork of injury depths in the same wound. One area might have been shielded by clothing while an adjacent spot took the full force of the radiant flash. Molten metal droplets land unevenly across exposed skin, creating scattered deep burns surrounded by more superficial injury. This heterogeneity makes it hard to draw clean boundaries between what will heal on its own and what will need surgery.
Deep Tissue Damage Below the Surface
When an electrical arc also delivers current through the body, not just radiant heat to the surface, the injuries become far more complex. Current follows the path of least resistance through tissue, which often means traveling along blood vessels, nerves, and muscles. Bone, which has high resistance, can generate intense heat at its interface with muscle. Deep tissue injury frequently evolves over time as blood vessels along the current pathway become progressively damaged, cutting off oxygen supply to surrounding muscle. This ongoing vascular compromise can lead to muscle death well after the initial event.3IntechOpen. Electrical Burn
Two serious complications arise from this deep muscle destruction. The first is rhabdomyolysis, where dead muscle releases its contents into the bloodstream. The protein myoglobin, released in large quantities from dying muscle fibers, can clog the kidneys and cause acute kidney failure. The second is compartment syndrome, where swelling within a rigid muscular compartment builds pressure to the point where blood can no longer flow in, threatening the limb. Rhabdomyolysis after electrical burns is a well-recognized clinical entity, and the combination of capillary leak and multi-compartment swelling can be devastating after major burns.4PubMed Central. Rhabdomyolysis, compartment syndrome and thermal injury Decision-making for these patients is complicated by the need for urgent surgical decompression of compartment syndrome alongside a more difficult fluid resuscitation, since the risk of rhabdomyolysis from deep tissue injury changes how much and how fast fluid should be given.5Total Burn Care. Electrical Injuries
This is the central reason arc burns with electrical current involvement are treated so differently from ordinary thermal burns. A person with a relatively small-looking skin wound on their hand and forearm may have massive muscle destruction underneath that requires emergency surgery. The external burn area can dramatically understate the total volume of damaged tissue.
Eye Injuries from Arc Radiation
The intense ultraviolet radiation produced by an electrical arc poses a serious threat to the eyes, even during brief exposures. The most common eye injury is photokeratitis, often called “arc eye” or “welder’s flash,” a painful inflammation of the cornea that feels like sand in the eyes and usually resolves within a day or two. Most welders have experienced this at some point.
More concerning, and less well-known, is the possibility of permanent damage to the retina. In one documented case, a man who performed electric arc welding for roughly 10 to 15 minutes without eye protection in a confined space developed lasting macular damage. His visual acuity dropped significantly, and imaging showed disruption of a critical layer of the retina in both eyes. The decreased vision persisted for at least 18 months after the exposure.6PubMed Central. Maculopathy from an accidental exposure to welding arc This kind of macular injury, called photic maculopathy, occurs because the intense light overwhelms the retina’s photoreceptor cells, essentially cooking them. Unlike arc eye, which is superficial and heals, retinal damage of this kind can be permanent.
The practical takeaway is that even short, unprotected exposures to arc light can cause damage that goes beyond the familiar painful-but-temporary flash burn of the cornea. Workers in confined spaces are at particular risk because reflected UV light can reach the eyes from multiple angles, and the cramped conditions sometimes make proper face shields impractical to wear.
Cardiac Risks After an Arc Burn
When electrical current passes through the body, the heart is a primary concern regardless of how stable the patient appears afterward. Electrical injuries can range from minor skin burns to life-threatening internal organ damage, and the main worry in a person who seems fine after an electric shock is the potential for delayed heart rhythm disturbances that may not show up for hours.7European Heart Journal. Electrical cardiac injuries: current concepts and management The heart’s electrical conduction system can be disrupted by external current, causing arrhythmias that range from benign extra beats to ventricular fibrillation, which is essentially cardiac arrest.
This is why patients with significant electrical burns are monitored on cardiac telemetry, often in an intensive care unit, even if they walk into the emergency room feeling relatively normal. The risk of delayed arrhythmia is real enough that hospital protocols typically call for at least 24 hours of continuous heart monitoring after a high-voltage electrical injury. Low-voltage injuries, roughly below 1,000 volts, carry a lower cardiac risk but are still taken seriously if the current pathway crossed the chest.
Arc flash injuries that are purely thermal, where the person was burned by the heat and light of the arc but no current actually passed through their body, generally do not carry this same cardiac risk. The distinction matters for triage: a worker who was struck by radiant heat but never touched a live conductor is treated differently from one through whom current flowed.
Treatment Priorities and Surgical Decisions
Treating an arc burn follows the same initial steps as any major trauma. The airway comes first, especially if the face or neck were exposed to the arc flash, since swelling from inhaled superheated air can close the airway rapidly. Fluid resuscitation starts immediately to support blood pressure and protect the kidneys, with adjustments if deep muscle injury is suspected. As noted earlier, the possibility of rhabdomyolysis changes the fluid calculation, typically requiring more aggressive hydration to flush myoglobin through the kidneys before it can cause damage.
The surgical timeline depends on whether compartment syndrome is developing. If pressure measurements in the limbs are rising, emergency fasciotomy, a procedure where the surgeon cuts open the tight fascial coverings of muscle compartments to relieve pressure, may be needed within hours. This can be limb-saving but leaves large open wounds that require staged reconstruction later.
For the burn wounds themselves, dead tissue is removed surgically in a process called debridement, often in repeated sessions over days because the full extent of tissue death may not be apparent at first. Skin grafting follows once the wound bed is clean and stable. In high-voltage arc burns where current has passed through the body, surgeons sometimes need to explore the wound in the operating room specifically to assess muscle viability, since surface inspection alone cannot reveal how much tissue is alive underneath.
Rehabilitation after a serious arc burn is often prolonged. Deep burns over joints cause tight scarring that restricts movement, requiring physical therapy and sometimes additional surgeries to release scar contractures. Nerve damage from the electrical current can cause lasting numbness, weakness, or chronic pain in the affected limbs.
Assessing How Deep the Damage Goes
One of the persistent challenges with arc burns is figuring out exactly how deep the injury extends. Clinical examination, meaning a trained eye looking at the wound, remains the standard starting point, but its accuracy is limited, especially in the first 48 hours. Currently, the only imaging tool with strong evidence supporting its use alongside clinical evaluation is laser Doppler imaging, which measures blood flow in the wound bed to help distinguish tissue that will heal from tissue that will not.8Burns. A comparison of non-invasive imaging modalities: Infrared thermography, spectrophotometric intracutaneous analysis and laser Doppler imaging for the assessment of adult burns Other imaging approaches, including infrared thermography and spectrophotometric analysis, have shown promise in early studies but haven’t yet accumulated the same evidence base.
For injuries involving deep muscle and internal structures, standard imaging like CT or MRI can help map the extent of damage, but even these have limitations. Dead muscle and live muscle can look similar on early scans. Surgeons often rely on direct visualization during surgery, checking whether muscle bleeds and contracts when stimulated, as the most reliable method. This reality, that the full picture often requires opening the wound, is part of why high-voltage arc burns carry such high rates of multiple trips to the operating room.
New Injury Patterns in Electric Vehicle Manufacturing
Arc burns are not just a concern in traditional electrical work. The rapid growth of electric vehicle manufacturing has introduced workplace hazards that were rare or nonexistent a decade ago. A review of patients admitted to a burn center from EV manufacturing facilities identified three recurring categories of injury: flash burns from lithium-ion battery explosions, high-voltage electrical injuries, and burns from contact with molten metal used in production processes.9PubMed Central. Burns Resulting From Electric Vehicle Manufacturing in Silicon Valley
The high-voltage electrical injuries in these settings are particularly concerning because EV battery systems operate at voltages well above what workers in traditional automotive manufacturing encounter. A conventional car’s electrical system runs at 12 volts. An EV battery pack can operate at 400 to 800 volts or more, putting it squarely in the range where arc flash events and current-through-the-body injuries become serious risks. Workers handling damaged or defective battery modules face additional dangers because lithium-ion cells can undergo thermal runaway, a self-sustaining chemical reaction that produces intense heat, toxic gases, and sometimes explosive force.
These injury patterns are new enough that many burn centers are still developing protocols specific to them. Lithium-ion battery fires, for instance, are notoriously difficult to extinguish and can reignite hours after they appear to be out. The chemicals involved can cause burns that behave differently from conventional thermal or electrical burns, and first responders may not yet be trained to recognize or manage them. As the EV industry scales up, the expectation among burn specialists is that these injuries will become more common, making prevention efforts and worker training in this sector increasingly important.
Arc Burns Versus Other Electrical Burns
People sometimes use “electrical burn” and “arc burn” interchangeably, but they are not the same thing, and the distinction has real clinical consequences. An arc burn can be purely thermal: the arc superheats the surrounding air and radiates intense energy, and the person is burned by that heat without electricity ever flowing through their body. Think of it like standing too close to an explosion. The skin burns, the eyes can be damaged, clothing can ignite, but no current enters the body. These are sometimes called arc flash burns, and they are treated essentially like any severe thermal burn, without the cardiac monitoring or the concern for deep internal muscle damage.
A true electrical burn, by contrast, involves current entering the body at one point and exiting at another. The tissue between those points is damaged from the inside out. Some arc events produce both: the arc flash burns the surface, and current simultaneously flows through the body. These combined injuries are the most dangerous because they carry every type of damage at once, surface burns, deep muscle destruction, cardiac risk, and potential kidney injury from rhabdomyolysis. When emergency teams evaluate a patient after an arc event, one of the first questions they try to answer is whether current actually passed through the body or whether the injury is thermal only, because the monitoring, imaging, and surgical urgency differ substantially between the two.
A third category worth knowing about is the arc blast injury, which is caused by the pressure wave from the explosive expansion of air during the arc event. This can throw a person across a room, rupture eardrums, and cause blunt trauma injuries on top of the burns. In a severe industrial arc flash, a patient might arrive at the hospital with thermal burns on exposed skin, electrical injury through one arm, a concussion from being thrown into a wall, and hearing loss from the blast. Each of those injuries has its own treatment pathway, and managing them simultaneously is what makes arc events so challenging from a medical standpoint.