An electrical burn is a tissue injury resulting from the passage of electrical current or heat from an external electrical source. The damage is often disproportionately greater beneath the skin than what is visible on the surface. Unlike standard thermal burns, electrical energy travels through the body’s internal structures, causing widespread destruction to nerves, muscles, and organs. This internal damage makes initial assessment challenging, as seemingly minor skin contact points may conceal severe underlying trauma.
Common Sources of Electrical Injury
Low-voltage injuries, defined as less than 1,000 volts, commonly occur in residential settings. These incidents often involve accidental contact with faulty household appliances, exposed wiring, or improper use of extension cords and wall outlets. Children frequently sustain low-voltage burns from biting or chewing on electrical cords.
High-voltage injuries, involving 1,000 volts or more, are often associated with occupational settings or major infrastructure. These sources include contact with overhead power lines, substations, or large industrial machinery. Accidental exposure can happen when engaging in activities near high-tension lines or when downed lines are encountered.
Lightning strikes represent an extremely high-voltage, high-amperage, but ultra-short duration natural cause of electrical injury. While less common than household or industrial accidents, lightning delivers a massive burst of energy that can result in significant injury or fatality.
Mechanisms of Tissue Damage
Electricity damages human tissue primarily by converting electrical energy into heat as it passes through the body, a process known as Joule heating. The body acts as a resistor to the flow of current, generating destructive thermal energy. The amount of heat produced is directly related to the resistance of the tissue and the magnitude of the current.
Tissues within the body vary widely in their electrical resistance, which dictates the pathway of the current. Bone, with the highest resistance, generates the most heat and sustains severe, deep thermal damage. Conversely, tissues with high fluid and electrolyte content, such as nerves, blood vessels, and muscles, have lower resistance and act as better conductors.
The current tends to follow these paths of least resistance, which is why deep structures are often damaged far more severely than the skin suggests. This movement of current causes coagulation necrosis and massive tissue destruction beneath the skin surface. Beyond the thermal effect, the electrical current can also directly interfere with the body’s own electrical systems, such as the heart’s rhythm and nerve impulse transmission.
Classifying Electrical Burns by Mechanism
Electrical burns are classified by the mechanism of injury, which helps determine the extent of internal damage. A True Electrical Injury, or contact injury, occurs when the current passes directly through the body, completing an electrical circuit. These injuries are often characterized by an entrance and an exit wound where the current contacted and left the body. The severity of the internal injury is determined by the path the current took between these two points.
Arc Flash Burns result from the intense heat and light generated when electricity jumps a gap in the air. This arcing does not necessarily require the current to pass through the victim’s body to cause injury. The flash can reach temperatures of several thousand degrees, causing severe external, thermal-type burns to the skin and clothing from the radiant heat. These burns are often superficial compared to true electrical injuries but can still be extensive.
Flame Burns, or thermal burns, are a secondary result of electrical contact. This happens when the heat from an electrical arc or the current itself ignites the victim’s clothing or surrounding combustible materials. The resulting injury is a standard thermal burn caused by fire, rather than the current passing through the body. A single incident can often result in a combination of true electrical, arc flash, and flame burns.
Factors Determining Severity and Internal Impact
The severity of an electrical burn is determined by several factors. Voltage is important because higher voltage drives a larger current through the body, increasing energy transfer. However, the total duration of contact is also influential, as a longer exposure allows more time for heat generation and tissue destruction.
The specific pathway of the current through the body is a critical determinant of internal impact. A current traveling from one arm to the other, or from an arm to a leg, is particularly dangerous because it may traverse the chest, putting the heart and lungs at risk. Even a small current passing through the heart can disrupt its electrical rhythm, potentially causing cardiac arrest.
The internal impact often includes damage to skeletal muscle, a condition called rhabdomyolysis, which releases muscle breakdown products into the bloodstream. This can overwhelm the kidneys and lead to acute renal failure. The nervous system is also highly susceptible, leading to potential nerve damage, seizures, or loss of consciousness. The seemingly minor surface wounds of an electrical burn can be highly misleading regarding the true extent of systemic trauma.