Sixteen-month-old Trinity Anderson was recently released from a hospital in Colorado. Trinity suffered from a shock received from placing the end of the iPod charging wire dangling from her mother’s computer.
USB and Firewire cables run everywhere from ordinary laptops and PCs. Are they dangerous? Furthermore, can they be lethal?
Let’s talk electrical 101. Electricity is based on voltage, amperage and resistance. I will reference electricity to water traveling through a hose. Voltage is similar to the force of the water; the higher the voltage, the higher the force of the actual electricity. The amperage is equated to the water. Water departing a garden hose aiming at your chest may be annoying, but will not thrust you to the ground as will a firefighter’s hose with more force (voltage) and water (amperage). Lastly is resistance. Similar to getting knocked over with the fireman’s hose, the more resistance we place against the water, the more it takes to knock us over.
Hold the end of a USB device in your hand; you are not likely to get shocked. The force or voltage is low, and the resistance of your skin is high, place it in your moist mouth and the resistance lessens, thus risk of shock proportionately increases. This is based upon the theory of Ohms Law.
High voltage can leap or arc further than low voltages. However, it is the amperage which does the damage.
Since so many factors are involved in electricity, it is impossible to determine what combination under various conditions can kill or seriously injure someone.
I spoke to several electrical engineers, which is where my professional background lies outside of my passion for music. One noted “Most people don’t realize it, but currents as low as 100mA (one tenth of an amp) can throw the human heart into ventricular fibrillation which can soon be followed by death. It is really the current that kills people, not the voltage. That is why you can get zapped by a 2.8 million volt stun gun, and (eventually) walk away from it – because despite the very high voltage, the current is very low.”
The article about young Trinity mentioned an improperly grounded lamp. In layman’s terms, the lamp could be source of the shock, and the USB cable the return path to ground.
Another engineer stated: “Before too much speculation goes into this thing, the article indicates that there is some doubt about the sequence of events or the source of the injury. While it is possible to cause an arrhythmia with pretty small amperage (AC being much more effective than DC), the burns indicate a substantial current. A normal USB cable is energized at both a low voltage and limited to a low amperage… There is talk about brain damage in the article that seems just farfetched from this type of injury. Keeping small children, dogs and other living things from putting live wires in their mouths is a pretty basic safety tip. But the accident as reported is freakish.”
Additionally, I have heard rumors of iPod listeners getting shocked from ear buds. Is it possible to get shocked through ear buds?
One electrical engineer documented his personal experience on the subject: “I, myself, have experienced shock thru ear buds, however, it was not due to electrical malfunction of the device. My situation was due to static electricity build up in my body as I walked on a treadmill. The ear buds had a metal piece on the grill covering the tiny speaker connected to the ground/shield of the ear bud cable. Periodically as the static electricity built up in my body, it would discharge on the metal piece of the grill of the ear bud. The static electricity discharge inside my ear canal was quite painful. I resolved the issue by replacing the ear buds with foam covered headphones!”
Therefore, how dangerous are those cables and cord, to us, our kids and pets? It’s extremely unlikely that the five volts from the USB plug caused burns. I believe this incident to be a freak accident. Exercise safety and prayer under all circumstances.