Protect your data from power hits

July 12, 1999|By Mike Himowitz

A couple of days of 100-plus temperatures last week reminded me that it's time to remind you that it's time to make sure your computer survives the summer.

Sweltering temperatures in July and August produce frequent thunderstorms, along with power outages that can last anywhere from a few seconds to a few hours. These are bad news for anyone who depends on a PC, because your PC depends on a steady supply of clean electrical power.

If the power goes out while your PC is writing information to your hard drive, you can wind up with a scrambled disk and irretrievable data. Unfortunately, the latest versions of Windows and Mac operating systems are constantly reading from and writing to your drive, even when you're not doing anything.

Just as importantly, modern operating systems must be properly shut down so they can close temporary files and record the system settings they'll need to know next time you start your PC. Pulling the plug while they're running can cause trouble.

The bottom line: Your PC is vulnerable to damage from a power outage virtually anytime it's turned on.

But the damage that occurs when the lights go out might be nothing compared to the damage that can occur when the juice comes back on. That's because the electricity often returns with a surge that can fry your PC's delicate circuits.

In our area, power interruptions are usually brief, but it's not unusual for the electricity to come back on for a minute or two, go out again, then come back on. Sometimes it will take seven or eight of these off-on cycles before the power stabilizes. This is the worst of all worlds for your PC.

Even when the electricity stays on, your PC is at risk from brownouts, which occur when the power company deliberately lowers the voltage during periods of peak demand.

Modems, meanwhile, are particularly vulnerable to fluctuations in phone-line current that can occur during a thunderstorm. There's virtually no warning that this is happening, and the fluctuations are so tiny that they won't affect the rest of your system. Nevertheless, they're enough to knock out a modem's electronics.

Fortunately, you can do something to prevent these problems. At the very least, make sure your computer, monitor and other gadgets are plugged into a good surge suppressor. These are devices that react instantly to dangerous surges, cutting off the power before it can damage your PC. Most power strips designed for electrical devices have some sort of surge protection built in, but it's wise to avoid the $8 bargain-basement models and buy a good one. Better units can clamp down more quickly on spikes, protect your computer from higher voltages and "filter" the electric current to avoid normal glitches in the power stream that can affect your PC's performance.

A good surge suppressor will also have phone jacks to protect your modem. You'll need an extra phone cord, though. One cord goes from your modem to the power strip, the other from the power strip to the wall jack.

No matter how good they are, surge suppressors eventually wear out. In fact, each surge destroys some of the suppressor's capacity to protect against future problems. So it's a good idea to replace units that have been around for a couple of years, particularly if you're in an area with frequent power losses.

Even the best surge suppressor won't keep your computer running when the power goes out. For that you'll need a battery backup, also known as an uninterruptible power supply (UPS).

A UPS is a box that sits between the wall outlet and your PC. You plug the UPS into your wall and your system components (computer, monitor, modem, etc.) into the UPS, which typically has four to eight outlets.

Inside the UPS you'll find a rechargeable battery and a collection of suppression and filtering circuits designed to provide the cleanest possible power to your system. If the power should fail, even for a fraction of a second, the battery kicks in and your computer never knows the difference.

In addition to outlets with backup power, most UPS units have outlets that aren't backed up, but do have excellent surge suppression. These are good for peripherals such as printers and scanners that aren't critical to your operations.

UPS units are considerably more expensive than surge suppressors, starting at about $100, but given the constant activity of today's computers, they're worth the money.

More expensive UPS units provide more power for longer periods of time. The cheapest battery backups will keep a low-end computer and 15-inch monitor running for about five minutes. That's fine for quick on-off failures and enough time to shut your system down if you're around, but not enough if you're more than a few minutes away from your desktop.

More powerful computers with 17- or 19-inch monitors eat electricity much faster than low-end models, so buy your UPS accordingly.

The price can go up pretty quickly -- for example, to keep a well-equipped Pentium III system running for 30 minutes, American Power Conversion (APC) recommends a unit that costs $560. But you can spend about half that if you're willing to settle for 10 minutes of running time.

Whatever unit you buy, maximize its lifesaving capacity by plugging only your computer and monitor into backed-up outlets. Use outlets without backup for your other gizmos. And never plug a laser printer into a backed-up outlet -- its heating element can drain the UPS battery in no time and even cause serious damage.

You can find UPS units at most well-equipped computer retailers. But before you buy, you'll probably want to visit Web sites sponsored by two of the largest UPS manufacturers, APC ( and SL Waber ( They can help you calculate your power needs.

Have a safe computing summer!

Pub Date: 07/12/99

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