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Electrical shocks

I distinctly recall, as a kid in junior high, being required in shop class to stand in a circle holding hands with my classmates, two of whom were attached to opposite sides of a small hand-cranked electrical generator. Somebody (probably the teacher) cranked the generator, and the rest of us were expected to “ooh” and “aah” over the tingling of a tiny electrical current flowing through the entire circle.

Personally, I didn’t much care for the sensation. I cared for it even less later that year when I accidentally switched the generator we used in electronics class from 1.5 volts DC to 115 volts AC, frying a DC voltmeter and not doing myself any good, either, since I was holding on to two wires connected to that generator. Then, in high school, there was the time I was playing electric bass while standing on wet ground…

Probably everyone has such shocking stories in their past. People older than I am may have even more stories to tell, because it’s only about 30 years ago that our electrical systems were redesigned to reduce the risk of shocks.

Electricity comes into your house through the electrical panel, which then distributes it to various branch circuits, providing power to outlets, lights and appliances. The panel contains fuses and/or circuit breakers, designed to burn out or pop open, cutting off current, whenever too much is flowing through the wires (which could cause them to overheat and burn the house down).

Most devices that use electricity plug into a wall socket. Until the 1960s, most plugs had two identical prongs. Since then, the three-prong plug (two flat and one rounded) and the plug with two different prongs (one wider than the other) have become the norm.

The newer styles are safer because they prevent you from sticking the plug in upside down. While doing so won’t keep the appliance from working, it does increase the hazard of shocks. Within the receptacle, one socket is “hot” and the other is neutral. The “hot” wire (usually covered with black insulation) carries voltage to the system, and is the one you never, ever want to touch. The other wire, usually white, carries little voltage. It provides a path for electrical current to flow back to the electrical panel, completing the circuit.

Within an appliance, one wire is also expected to be hot and one neutral. As a result, the neutral one is generally less well-insulated If you stick the plug in upside down, however, the neutral wire becomes the hot wire. This is particularly hazardous in light fixtures, where the hot wire emerges deep in the bulb socket, where you’d have to work to touch it, while the neutral one is connected to the socket itself. Should you then be changing a light bulb and accidentally touch the socket, you could get a nasty shock.

The newer-style two-pronged plugs ensure that “hot” goes to “hot” by making it possible to stick the plug in only one way. The wide blade connects to the neutral wire and the narrow blade to the hot wire. The three-pronged plugs accomplish the same thing, since you can only stick them in one way. They also add an additional feature, a ground wire.

Electricity, like water, always flows “downhill,” areas of high potential to areas of low potential. The earth is like a huge sponge when it comes to soaking up electrical charges, so if electricity can find a path to the earth, it will take it. This is what grounding is all about. That third wire in a three-pronged plug attaches to the metal parts of an appliance, the parts that might carry stray current, and, at the other end, is attached to the ground, through a copper rod or even a water pipe. Electricity would much rather flow along a metal wire than through our bodies, and it’s eager to get to the ground, so this prevents shocks.

When you do get shocked, its because for some reason YOU provide electricity with the path of least resistance. You don’t really conduct electricity very well, so you’re usually not in too much danger unless you’re grounded. Then electricity eagerly flows through you to get to the earth. Standing barefoot on wet ground while sticking a knife into the hot side of an electrical socket, then, would qualify as a Bad Thing to Do. You can also be grounded without realizing it, however; standing on a metal ladder, for instance, or, for that matter, standing in your wet bathtub: water conducts electricity and, through the pipes, is grounded, so you’re grounded, too.

Most shocks are felt just as a slight tingle, but it takes surprisingly little current to cause serious injury, or even kill. How severe the injury is depends on voltage, current, resistance and duration of contact. Voltage isn’t the most important factor; current, measured in amps, is. You can feel as little as 1 or 2 milliamps of current; someone grabbing 10 or 15 milliamps wouldn’t be able to let go; cardiac arrhythmia can result from 50 to 500 milliamps; breathing can be stopped by 100 milliamps to 1 amp, and more than 500 milliamps can cause serious burns. When you consider that a typical electric frying pan may have has much as 10 amps flowing through it, you begin to realize that electricity is potentially (pardon the pun) the most dangerous thing we have in our house.

Within the body, the path of least resistance is along the nerves and blood vessels. (That’s why we can feel even a tiny amount of current; it’s flowing along our nerves.) As a result, an electrical burn may appear small on the surface even though there’s severe damage inside: internal bleeding, internal burns, nerve damage. Respiratory and cardiac arrest can result from severe shocks.

Electricity, then, is nothing to play around with. That’s why breaking off that rounded prong so you can use your three-prong plug in a two-prong hole, or filing down the wide blade on a plug so it’ll fit in your old sockets, is not a good idea.

Oh, yeah, and one other tip: don’t hold onto two wires connected to a 115-volt AC generator.

Trust me on this.

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