Electrical burns result from contact with an electrical current and differ significantly from standard thermal burns caused by heat alone. While the skin may show relatively minor damage, the flow of electricity through the body can cause severe, deep-seated injury to internal tissues and organs. Understanding how electricity causes harm is important because the dangers are often hidden beneath the surface of the skin, requiring a distinct medical approach.
How Electrical Current Damages Tissue
The most direct cause of injury from electricity is the passage of current through the body, which converts electrical energy into thermal energy inside the tissues. This conversion occurs due to a physical principle known as Joule heating, where the resistance encountered by the flowing current generates heat. The amount of heat produced is proportional to the square of the current, meaning a small increase in current can result in a disproportionately large rise in temperature inside the body.
The skin, particularly when dry, offers the highest resistance and acts as the primary barrier to current flow. Once the current bypasses the skin, it travels along paths of least resistance, which are tissues with high water and electrolyte content. Nerves, blood vessels, and muscle tissue offer low resistance, making them highly susceptible to damage as the current propagates.
The resulting deep thermal damage is often substantial, appearing far worse than the modest entrance and exit wounds visible on the skin’s surface. This internal destruction can lead to the widespread death of muscle tissue, which releases toxins into the bloodstream. Because deep tissues like bone have the highest resistance, they heat up intensely, causing severe damage to surrounding muscle and potentially resulting in amputation.
Types of External Electrical Burns
Electrical events can cause thermal injuries that do not involve the current passing through the victim’s body, categorized as external burns. These burns are fundamentally thermal in nature, stemming from the extreme heat generated by the electrical source itself.
One common external injury is the arc flash burn, which occurs when an electrical current jumps through the air between two conductors. This arcing creates an extremely hot plasma, which can reach temperatures as high as 36,000 degrees Fahrenheit. The intense thermal radiation causes severe external burns to exposed skin and clothing, even if the current never enters the body.
Electrical events can also cause flame burns, also known as thermal-contact burns. This happens when the heat from an electrical arc or initial current contact ignites a person’s clothing or nearby flammable materials. The resulting fire causes standard fire-related burns that complicate the primary electrical injury.
Variables That Determine Injury Severity
The severity of an electrical injury is heavily influenced by several modifying factors beyond the source of the electricity. The relationship between voltage and current, described by Ohm’s Law, is a primary determinant of injury magnitude. Voltage determines the driving force, but the actual tissue damage is proportional to the amount of current, or amperage, that flows through the body.
Duration of Contact
The duration of contact is an important variable because the longer the current flows, the greater the total energy delivered to the tissues. Even relatively low-voltage sources can cause severe injury if the contact is prolonged, allowing for continuous Joule heating and deep tissue destruction. This often occurs when muscle contractions, caused by alternating current, prevent a person from letting go of the electrical source.
Current Pathway
The path the current takes through the body is one of the most critical factors in determining systemic injury. Current traveling from one hand to the other, or from a hand to a foot, is dangerous because it crosses the chest and may disrupt the heart’s electrical rhythm, potentially causing cardiac arrest. Conversely, current confined to an extremity, such as a finger, is less likely to cause a fatal systemic complication.
Tissue Resistance and Moisture
Tissue resistance also plays a role, with moisture significantly lowering the skin’s natural protective barrier. Sweat or water on the skin dramatically reduces resistance, allowing a much greater current to enter the body at a given voltage. A wet environment, therefore, increases the current flow and the subsequent severity of the internal burn.