The paradox of external power

The paradox of external power

External power, which comes from your home or office wall outlet, is the power everyone tends to take for granted--as long as it's there, it's fine. You may be surprised at the number of problems external power can have: line noise, spikes, surges, brownouts, and blackouts, among the major ones. Most of these problems go unnoticed, because they are usually small enough that the computer's power supply can deal with them (all except a blackout, of course). But, these power problems can lead to reliability problems in your computer.

When you plug your PC directly into the wall socket, you are subjecting the PC to several problems.

Some of these problems your computer can handle, but over time, even unnoticed problems can take their toll and result in major damage. You should know for the test the kinds of problems that the PC can experience from external power. These problems are

l Line noise: Consists of small variations in the voltage of the power line. A small amount of line noise is normal in just about every system, and all but the very cheapest power supplies can handle it. If you have the PC plugged into its own circuit (un shared line), you should have little trouble from line noise. However, if your computer shares an extension cord with the pop machine or its circuit with a megaton air conditioner, line noise is a certainty, and it will soon cause some major problems. What will usually happen is that the line noise eventually burns out the power regulating circuits in a PC's power supply. After that, any line noise on the power line could pass through the power supply unscathed straight to the motherboard or disk drives and the other unsuspecting internal components of the PC.

l Power surges: A power spike, which is called an over voltage event by the power company, happens when disturbances, such as distant lightning strikes or other anomalies in the electrical supply grid, create a voltage spike that travels down the line and to your wall plugs. The surge lasts only a few thousandths of a second, but that's plenty of time for the voltage to increase to 1,000 volts or higher. High voltage spikes can degrade a PC's power supply. Multiple surges over time can destroy it.

l Brownouts: Called an under voltage event by the power company, a brownout is the opposite of a power surge (over voltage event) and happens when a sudden dip occurs in the power line voltage.

A brownout doesn't typically last too long, but it can. In most cases, the power level drops below normal levels for a time and then returns to normal. Brownouts are extremely common during periods of heavy load on the electrical system, such as hot afternoons or cold mornings. The reduced voltage level causes many devices to run slower than normal or malfunction in other ways. Low voltage for an extended time can do just as much damage as spikes.

l Blackouts: A blackout occurs when the power fails completely. The problems caused by a blackout are usually more frustrating than damaging, but the fluctuation of power surrounding a blackout can harm your system. If you're in the middle of a long document (that you hadn't yet saved), or were de-fragmenting or fixing other hard disk problems (and the allocation tables weren't completely rebuilt) when the power goes out--you very likely have problems. More often, though, the damage occurs when the power returns suddenly, usually in the form of a huge spike.

l Lightning strikes: This is the big spike, and it can deliver a million volts or more. I don't need to tell you what would happen if one were to hit your home or office directly. However, a strike even in the vicinity can result in a very high voltage spike. I have witnessed what a lightning strike can do to a building. Everything plugged in was completed destroyed or melted down: computers, copiers, fax machines, telephones, and more.