|
Capacitors (or condensors) storage energy as an electric field. A leyden jar is an example of a capacitor. Most capacitors in electronic or automotive system are small and are unlikely to present any danger. Larger capacitors, such as those used on power supplies for electronics or on capacitor start/run motors, are hazardous if they are installed in such a way that they can't discharge. (For example, if the capacitor is in series with a switch.) These sorts of capacitors are generally metal cylinders an inch or more in diameter. Large capacitors that have been hooked up to line voltage then disconnected (such as starter capacitors for motors) may have enough voltage on them to electrocute you. Or they may have no voltage, since line voltage cycles at 60 cycles per second. DC power supply capacitors are a greater danger, especially those for high power amplifiers. They can have 100 volts or more on them, and store enough power to do some real damage if discharged. If they are properly connected, usually a resistor is connected across the capacitors terminals to discharge it. If the discharge resistor is damaged or disconnected, a large power supply capacitor can be very dangerous. The real dangerous capacitors are those used in power distribution for power factor correction. They are quite large (store a lot of energy), and are generally used at dangerous voltages. You should never mess with one of these if you don't know what you're doing. Note that a good capacitor can pick up static charges if it isn't connected to some sort of load or short circuit. Treat all large capacitors as charged unless you know otherwise. The safest way to discharge a capacitor is with a several thousand ohm resistor. Directly shorting a charged capacitor will draw an arc.
| 
