Electrical injuries result from contact with an electrical current or the heat it generates. These incidents can cause extensive damage to internal organs, deep tissues, and physiological systems, often leading to long-term disability or death. The severity is influenced by factors such as voltage, current type, duration of exposure, and the path the current takes through the body. Electrical injuries are categorized into four distinct types, each defined by a different mechanism of harm.
Systemic Damage from Electrical Shock
Electrical shock occurs when a current passes directly through the body, interfering with the normal electrical signals of the nervous and muscular systems. This systemic disruption is the most life-threatening consequence because the body’s functions rely on precisely timed electrical impulses. The primary danger involves the heart, where an external current can override the natural pacemaker, leading to immediate cardiac arrest or ventricular fibrillation. Ventricular fibrillation is common with low-voltage alternating current (AC) because its frequency easily disrupts the heart’s rhythm.
The pathway the current travels significantly determines the potential for injury to vital organs. For instance, a current passing from one hand to the other is highly likely to cross the thorax and affect the heart and lungs. Beyond the heart, the nervous system can experience immediate effects such as the involuntary contraction of muscles, called tetany. If the current path crosses the chest wall, these spasms can paralyze the respiratory muscles, leading to respiratory arrest. Neurological damage can also result in delayed issues, including headaches, seizures, and long-term nerve damage.
Direct Contact and Internal Electrical Burns
Direct contact electrical burns are caused by the conversion of electrical energy into thermal energy when current encounters resistance within the body’s tissues. This mechanism, known as Joule heating, generates intense heat that destroys tissue along the current’s path. These injuries are characterized by small, often minor-looking entry and exit wounds on the skin. The skin’s high resistance causes significant superficial heating at the entry point, but internal tissues like nerves, blood vessels, and muscle possess less resistance and are heated along the path of current flow.
The most severe damage is often hidden from view, occurring in the deep tissues beneath the skin, including muscle, bone, and organs. Bone, having the highest resistance, heats up considerably, causing deep tissue necrosis and delayed damage to surrounding structures. Severe deep tissue damage may lead to compartment syndrome, where swelling cuts off blood flow to the limb, often necessitating emergency surgical procedures or amputation. The extent of internal destruction is directly related to the voltage, duration of contact, and the electrical resistance of the tissues involved.
Thermal Injury from Arc Flash
Thermal injury from an arc flash is fundamentally different from a direct contact burn because the electrical current does not pass through the body. An arc flash is a sudden, high-energy electrical explosion that occurs when a powerful current jumps through the air between two conductors. This event instantly releases tremendous energy in the form of intense light, heat, and pressure. Temperatures within the arc can momentarily reach up to 36,000 degrees Fahrenheit, which is hotter than the surface of the sun.
The injury is predominantly a deep thermal burn caused by the extreme radiant heat that strikes the person’s exposed skin and clothing. These burns can be severe and full-thickness, often affecting the face, neck, and hands. The intense heat can also vaporize metals and superheat the surrounding air, posing a risk of severe respiratory tract burns if inhaled. The rapid expansion of air creates a pressure wave, or blast, which can propel molten material and cause secondary mechanical trauma.
Injuries from Secondary Trauma
Secondary trauma refers to mechanical injuries that are a consequence of the electrical event but are not caused by the current or heat directly. The most common example is a fall from a height. If a worker receives an electrical shock on a ladder or scaffolding, the resulting jolt or loss of consciousness can lead to a severe fall.
The forceful, involuntary muscle contractions (tetany) caused by the electric current generate significant mechanical forces within the body. These violent spasms are strong enough to cause fractures of long bones or compress the spinal vertebrae. In an arc flash incident, the powerful pressure wave can throw a person backward, resulting in blunt force trauma as they strike objects or the ground.