An arc burn is a severe injury resulting from an electrical explosion known as an arc flash. This event occurs when high-amperage current leaves its intended path and travels through the air, releasing a massive amount of energy in a fraction of a second. The resulting thermal, radiant, and concussive forces cause complex injuries to the skin and internal body systems. Understanding the mechanism of this electrical event is the first step in appreciating its danger.
The Physics of an Arc Flash
An arc flash initiates when a fault current crosses an air gap between two conductors or a conductor and the ground. This surge of electrical energy instantly vaporizes metal components and the surrounding air. The air becomes ionized, creating a highly conductive channel of superheated gas called plasma, which sustains the electrical current outside the equipment.
This plasma arc is the source of the event’s power, releasing energy as extreme heat, intense light, and a massive pressure wave. Temperatures at the core of the arc can exceed 35,000°F (19,400°C), which is approximately four times hotter than the surface of the sun. This heat occurs within milliseconds, transferring energy to any nearby object or person.
The rapid vaporization of metal components, such as copper, creates an explosive physical force known as an arc blast. When metal changes from a solid to a gas, its volume expands dramatically; copper, for instance, expands by a factor of up to 67,000. This expansion produces a powerful concussive pressure wave that can travel at supersonic speeds.
The pressure wave propels shrapnel and molten metal droplets away from the equipment at high velocity, causing immediate physical trauma. The energy release continues until upstream protective devices, such as circuit breakers, detect the fault and interrupt the current flow. Because this process can take several cycles of electrical current, damage is often done by the time the circuit opens.
Categorizing the Injuries from Arc Exposure
The combined energy released by an arc flash event causes three distinct, often simultaneous, categories of injury. The primary injury is the thermal burn, caused by the extreme heat radiating from the arc. This radiant heat can ignite clothing and cause severe, deep-tissue burns even when a person is several feet away from the electrical source.
The intense flash of light from the arc is not merely visible light but also a massive burst of ultraviolet (UV) and infrared radiation. This radiant energy can inflict injuries similar to a severe sunburn on exposed skin. The UV radiation can also cause photokeratitis, or “welder’s flash,” which is a painful burn to the cornea.
The concussive force from the arc blast creates pressure wave injuries, which are mechanical in nature. This violent shockwave can result in blunt force trauma, throwing a person backward and causing broken bones or internal injuries. The pressure wave can also rupture delicate internal structures, causing hearing loss or ruptured eardrums due to acoustic shock that can exceed 140 decibels.
The vaporization of metal and insulation materials releases toxic fumes and particulate matter into the air. Inhaling these superheated gases can cause severe damage to the respiratory system, leading to pulmonary injuries and respiratory distress. In some cases, inhaling molten material can also lead to internal thermal burns.
Immediate First Aid and Medical Attention
The first priority following an arc burn incident is to ensure the area is safe before approaching the victim, as electrical hazards may still be present. Once the scene is secured, immediately calling emergency medical services is paramount for this severe, multi-faceted trauma. A person exposed to an arc flash requires prompt professional medical evaluation for internal and external injuries.
Cooling the burn area helps limit tissue damage and provides immediate pain relief. Apply cool, not freezing or icy, water to the affected area for ten to fifteen minutes. Avoid using ice, as the extreme cold can further damage the burned skin tissue.
Do not attempt to remove any clothing that has melted onto or adhered to the burned skin. Trying to pull off stuck fabric can cause catastrophic damage to the underlying tissue. Instead, carefully cut around the adhered clothing to remove the surrounding material.
For eye injuries, especially the intense pain and irritation from photokeratitis, the victim should avoid rubbing their eyes and seek immediate medical attention from an eye care specialist. While waiting for emergency services, cover the burn wounds with a clean, dry cloth or sterile dressing to prevent infection.