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By far, the single most dangerous aspect of working with electronics is the possibility of electrocution. Electrical shock results when the body reacts to an electrical current — this reaction can include an intense contraction of muscles (namely, the heart) and extremely high heat at the point of contact between your skin and the electrical current. The heat leads to burns that can cause death or disfigurement.
The degree to which electrical shock can harm you depends on a lot of factors, including your age, your general health, the voltage, and the current. If you're over 50 or in poor health, you probably won't stand up to injury as well as if you're 14 and as healthy as an Olympic athlete. But no matter how young and healthy you may be, voltage and current can pack a wallop, so it's important that you understand how much they can harm you.
Electricity = voltage + current
To fully understand the dangers of electrical shock, you need to know the basics of what two elements make up electricity: voltage and current.
Voltage and current work hand-in-hand and in ways that directly influence the severity of electrical shock. Consider the analogy of water flowing through a pipe. Think of the water as representing the electricity. Increasing the diameter of the pipe to let more water through is like increasing voltage. Imagine being under a drain pipe for the Hoover Dam! Increasing the pressure of the water in the pipe is like increasing current. You know that even small amounts of water at high pressure can be devastating. The same is true of electricity, where even low voltages at high currents can potentially kill you.
Is it AC or DC?
You can describe electrical current as being either of the following
- Direct (DC): The electrons flow one way through a wire or circuit.
- Alternating (AC): The electrons flow one way, then another, in a continuing pattern.
 | Household electrical systems in the U.S. and Canada operate at about 117 volts AC. This significantly high voltage can, and does, kill. You must exercise extreme caution whenever you work with it. |
 | Until you become experienced with working with electronics, you're best off avoiding circuits that run directly off household current. Stay with circuits that run off standard-size batteries, or those small plug-in wall transformers. Unless you do something silly, like lick the terminal of a 9-volt battery (yes, you get a shock!), you're fairly safe with these voltages and currents. |
The main danger of household current is the effect it can have on the heart muscle. High AC current can cause severe muscle contraction, serious burns, or both. And many electrocution accidents occur when no one is around to help the victim.
Burns are the most common form of injury caused by high DC current. Remember that voltage doesn't have to come from a souped-up power plant to be dangerous. For example, don't be lulled into thinking that because a transistor battery delivers only nine volts, then it's harmless. If you short the terminals of the battery with a piece of wire or a metal coin, the battery may overheat — and can even explode! In the explosion, tiny battery pieces can fly out at high velocity, burning skin or injuring eyes.
Trying to not get electrocuted
Most electrocution accidents happen because of carelessness. Be smart about what you're doing, and you will significantly reduce the risk of being hurt by electricity.
Here are a few handy electrocution prevention tips:
- Avoid working with AC-operated circuits. Of course, you can't always do this. If your project requires an AC power supply (the power supply converts the AC to lower-voltage DC), consider using a self-contained one, such as a plug-in wall transformer. They're much safer than a homemade power supply.
- Physically separate the AC and DC portions of your circuits. This helps to prevent a bad shock if a wire comes loose.
- Make sure you secure all wiring inside your project. Don't just tape the AC cord inside the project enclosure. It may pull out sometime, exposing a live wire. Use a strain relief or a cable mount to secure the cord to the enclosure. A strain relief clamps around the wire and prevents you from tugging the wire out of the enclosure. You can buy a strain relief for electrical cords at almost any hardware store or electronics shop.
- Whenever possible, use a metal enclosure for your AC-operated projects, but only if the enclosure is fully grounded. You need to use a 3-prong electrical plug and wire for this. Be sure to firmly attach the green wire (which is always the ground wire; ground is used as a reference for all voltages in a circuit) to the metal of the enclosure.
- If you can't guarantee a fully-grounded system, use a plastic enclosure. The plastic helps insulate you from any loose wires or accidental electrocution. For projects that aren't fully grounded, only use an isolated power supply, such as a wall transformer (a black box with plug prongs which is attached to a wire, such as you may have on your cell phone charger). You plug the transformer into the wall, and only relatively safe low-voltage DC comes out.
- Don't be the class clown. Be serious and focused while you're working around electricity.
- Don't work where it's wet. "Yeah, duh!" you say. But you'd be surprised what people sometimes do when they're not paying attention. And remember, just because you put liquid in a cup, that doesn't mean you don't run the risk of knocking it over and getting things wet; consider leaving your soft drink or coffee on an out of the way shelf when working on your electronics project.
| Practice the buddy system. Whenever possible, have a buddy nearby if you're working around AC voltages. You want someone around who can dial 9-1-1 when you're lying on the ground unconscious. Seriously. |
Getting a first aid chart
Of course, you're the safest person on earth, and you will never be electrocuted. But just in case, get one of those emergency first aid charts that includes information about what to do if anyone else (not you, of course) ever pokes his finger into a wall outlet. You can find these charts on the Internet; try a search for "first aid wall chart." You can also find them in school and industrial supply catalogs.
| Helping someone who has been electrocuted may require cardio-pulmonary resuscitation, otherwise known as CPR. Be sure that you're properly trained before you administer CPR on anyone. Otherwise, you may cause more harm than good. Check out the Red Cross to get more information about CPR training. |
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