Electric shock: Encyclopedia II - Electric shock - Issues affecting lethality

Electric shock - Issues affecting lethality

Other issues affecting lethality are frequency, which is an issue in causing cardiac arrest or muscular spasms, and pathway - if the current passes through the chest or head there is an increased chance of death. From a mains circuit the damage is more likely to be internal, leading to cardiac arrest.

The comparison between the dangers of alternating current and direct current has been a subject of debate ever since the War of Currents in the 1880s. DC tends to cause continuous muscular contractions that make the victim hold on to a live conductor, thereby increasing the risk of deep tissue burns. On the other hand, mains-frequency AC tends to interfere more with the heart's electrical pacemaker, leading to an increased risk of fibrillation. AC at higher frequencies holds a different mixture of hazards, such as RF burns and the possibility of tissue damage with no immediate sensation of pain. Generally, higher frequency AC current tends to run along the skin rather than penetrating and touching vital organs such as the heart. While there will be severe burn damage at higher voltages, it is normally not fatal.

It is believed that human lethality is most common with AC current at 100-250 volts, as lower voltages can fail to overcome body resistance while with higher voltages the victim's muscular contractions are often severe enough to cause them to recoil (although there will be considerable burn damage). However, death has occurred from supplies as low as 32 volts.

Electrical discharge from lightning tends to travel over the surface of the body causing burns and may cause respiratory arrest.

Electric shock - Point of Entry

Macroshock Current flowing across intact skin and through the body. Current traveling from arm to arm or between an arm and a foot is likely to traverse the heart and so is much more dangerous than current traveling between a leg and the ground.

Microshock Direct current path to the heart tissue

Adapted from the Wikipedia article "Issues affecting lethality", under the G.N U Free Docmentation License. Please also see http://en.wikipedia.org/wiki