When a person contacts a live electrical source, such as a light bulb socket, they experience an electric shock. While “electrocution” specifically refers to an electrical injury resulting in death, an electric shock is any non-fatal exposure to electrical current. Even common household voltage (120 volts) can deliver a current strong enough to cause serious injuries.
The Physics of Household Electrical Shock
The human body acts as a conductor, completing an electrical circuit when it touches a live electrical part and a grounded object simultaneously. Standard household electricity is Alternating Current (AC), which rapidly reverses direction, typically 60 times per second, making this frequency hazardous to the body’s internal systems.
Electricity follows the path of least resistance to reach the ground. If the body is part of that path, current flows through tissues and organs. The outermost layer of skin provides the primary resistance, but once breached, current passes easily through internal tissues, disrupting the body’s natural electrical signals used by the nervous system.
The flow of AC current involuntarily stimulates nerve and muscle cells, causing painful, uncontrolled contractions. Unlike Direct Current (DC), which often causes a single contraction that might throw a person clear, AC current induces a sustained muscle contraction called tetany. This sustained contraction prevents the person from letting go of the live source, prolonging exposure and increasing injury severity.
Immediate Physical Injuries Caused by Current
Thermal damage, caused by the current passing through tissue, is one of the most immediate effects of electric shock. This process, known as Joule heating, transforms electrical energy into heat, causing severe burns where the current enters and exits the body. While external burns may appear minor, internal current movement can cause significant destruction to underlying muscles, nerves, and blood vessels.
A primary danger lies in the current’s effect on the cardiovascular system. Even a small amount of current (50 to 150 milliamperes) passing through the chest can disrupt the heart’s natural rhythm. This often induces ventricular fibrillation—a rapid, uncoordinated twitching which stops the effective pumping of blood. Fibrillation is the most common cause of death in AC shock.
The nervous system also suffers damage when current passes through it. Immediate neurological symptoms include temporary paralysis, numbness, tingling sensations, and confusion. If the current passes through the head, rapid loss of consciousness is common. Victims may also experience delayed neurological consequences that manifest days or weeks later.
Factors Determining Shock Severity
The outcome of an electrical shock is determined by physical factors, not just the source voltage. The path the current takes through the body is a significant variable, as current passing through the chest cavity is far more likely to affect the heart and lungs. A shock traveling from hand-to-hand or through the torso poses the highest risk of fatal cardiac events.
The duration of contact is another determining factor; longer exposure allows more electrical energy to convert to heat and increases the time the heart is subjected to disruptive current. Skin resistance also plays a large role in how much current flows through the body. Dry, intact skin offers high resistance, limiting the current flow.
In contrast, wet skin, such as from sweat or standing in water, dramatically lowers resistance, allowing a much higher current to flow at the same voltage. While voltage provides the electrical pressure, injury severity is directly related to amperage (the amount of current). A low-voltage source can still be lethal if resistance is low.
Immediate Actions and Medical Evaluation
If an electric shock occurs, the immediate priority is safely separating the person from the current source without becoming a victim. This involves turning off the power at the main circuit breaker or unplugging the appliance. If power cannot be immediately disconnected, use a non-conductive object, such as a wooden broom handle or plastic item, to push the person away from the source.
Once the person is clear, check for breathing and a pulse, and administer CPR if necessary. Even if the shock seems minor, immediate medical evaluation is required. Internal injuries, particularly those affecting the heart and central nervous system, may not be immediately apparent.
A medical professional will perform an electrocardiogram (EKG) to check for hidden damage to the heart’s electrical system, which can result in delayed arrhythmias. Muscle enzymes may also be checked via blood tests to detect internal tissue damage that could lead to kidney problems. Any electric shock requires a thorough medical assessment due to the potential for serious, unseen complications.