An electrical shock from a standard household outlet (typically 120 volts) presents a serious hazard to the human body. The outcome depends heavily on factors like the path the current takes and the duration of exposure. Although the voltage is low compared to industrial sources, the potential for severe internal damage is a significant concern.
The Mechanism of Injury
The danger from an electrical shock is primarily determined by the amount of current, or amperage, that flows through the body, not solely the voltage rating of the outlet. According to Ohm’s Law, this current flow is inversely related to the body’s electrical resistance. Skin acts as the main barrier to electricity, and its resistance drops dramatically when it is wet or punctured, allowing a greater and damaging current to pass through.
The path the current travels is another determining factor. Current passing from one hand to the other, or from a hand to a foot, is particularly dangerous because it crosses the chest, putting the heart and lungs directly in the current’s path. Even a low-voltage shock can be fatal if the current is sustained or crosses these sensitive areas. The duration of contact escalates the risk, as longer exposure means greater energy transfer and tissue damage.
Immediate Physical Effects
One of the most immediate and visible effects of household alternating current (AC) is muscle tetany, the sustained, involuntary contraction of muscles. This occurs because AC electricity interferes with the body’s natural electrical signals that control muscle movement. If the current travels through the flexor muscles of the hand, it can cause the hand to clamp down onto the source, impossible to let go and prolonging the exposure.
If the current path affects the muscles of the chest, it can lead to temporary respiratory paralysis, making breathing difficult. The pain experienced is often a result of both the electrical stimulation of nerves and the thermal energy generated as the current passes through tissues. Electrical burns may appear at the entry and exit points, but the severity of these external marks does not always reflect the extent of internal injury.
Hidden and Delayed Health Risks
The most significant danger lies in damage that is not immediately visible. Current passing through the chest can disrupt the heart’s natural rhythm, leading to life-threatening conditions like ventricular fibrillation. This disorganized electrical activity prevents the heart from pumping blood effectively. Cardiac damage or other arrhythmias can occur even after a minor shock and may manifest hours or days later.
Neurological damage is also a serious concern, as nerve tissue is susceptible to electrical injury. People may experience temporary symptoms like confusion, headaches, or tingling, but more severe or delayed effects can include persistent numbness, weakness, or long-term nerve pain (neuropathy). The electrical energy converts to heat as it moves through the body, causing internal thermal injuries to organs, blood vessels, and deep muscle tissue.
Deep muscle damage can release breakdown products into the bloodstream, a condition called rhabdomyolysis. These substances can overwhelm and damage the kidneys, leading to acute kidney failure. Swelling from internal muscle damage can also create immense pressure within a confined space, causing compartment syndrome, which severely restricts blood flow and can result in the death of limb tissue if not treated promptly.
Essential Steps After an Electrical Shock
The first step in responding to an electrical shock is to safely separate the person from the current source without touching them directly. If possible, immediately turn off the power source at the circuit breaker or unplug the device. If the power cannot be turned off, use a dry, non-conductive object to push the source away from the person.
Emergency medical care should be sought immediately by calling 911 if the person has any severe symptoms, such as loss of consciousness, confusion, difficulty breathing, or visible severe burns. A medical evaluation is also warranted if the current traveled across the chest, or if the person has an irregular heartbeat or muscle pain. If the person shows no signs of circulation, cardiopulmonary resuscitation (CPR) should be started immediately until emergency services arrive.
For minor shocks that produce only a brief tingling sensation with no lasting symptoms, a person should seek a medical evaluation within 24 to 48 hours. Internal injuries can be difficult to detect initially, and a healthcare provider may perform tests, such as an electrocardiogram (EKG), to check the heart’s electrical activity. Any burns should be covered with a sterile gauze dressing while awaiting medical attention.