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Empowering PCs to handle surges, outages a wise move

NOT LONG AGO a reader called with a reasonable question. "I'm going on vacation," he said, "and I'm wondering if I should unplug my computer and other equipment while I'm gone."

The answer: It can't hurt. In fact, unplugging your gear while you're away can save a lot of grief in a season when thunderstorms pose a danger to virtually everything electronic.

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But the call reminded me that it's a good time to talk about making sure your computers, printers and other gadgets are protected against electrical surges and spikes - even when they're plugged in.

Surges and spikes are brief but spectacular increases in voltage that can fry delicate equipment. A surge lasts longer than a spike, but they're both very short - measured in nanoseconds, or billionths of a second.

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The biggest surge in nature is lightning, but contrary to popular belief, direct lightning strikes cause relatively few problems for homeowners because they're so rare. In fact, if lightning does strike your house or the power lines nearby, there's almost nothing you can do to keep your plugged-in equipment from frying, short of installing a whole-house surge suppressor - an expensive proposition.

Much more common are household surges, caused by heavy equipment such as air conditioners, freezers and refrigerators that cycle on and off, momentarily creating a jump in voltage. Often the damage is cumulative - you might not notice it till your computer or some other gadget quits before its time.

During the summer, lightning strikes can cause power interruptions, which create two potential headaches. The main problem is that power often returns with a surge in voltage that can damage unprotected components.

The second problem is that your computer could grind to a halt while it's writing data to the hard drive, which can scramble your data or even make the computer unbootable. Shutting down suddenly without properly closing important system files can cause trouble the next time a PC boots up, too - even if there's no real damage.

To deal with the first hazard, you'll need a good surge suppressor. For the second you'll have to go a step further - an uninterruptible power supply to keep your system chugging along.

Most surge suppressors are built into power strips that use a series of components known as Metal Oxide Varistors (MOVs). Their job is to keep normal voltage flowing through the outlets, but divert high-voltage surges to your home's grounding wire. In practice, they act much like a stout oak door protecting your castle against a battering ram. The first time the ram strikes the door, it's likely to hold, but over time, repeated battering will weaken the door- until a fairly strong blow breaks it down.

Over time, internal home surges, combined with outside surges, gradually burn out the MOVs in any suppressor. So it's a good idea to replace a power strip every couple of years, or immediately after you know it's taken a major hit (the biggest clue - the strip is blackened or melted).

When shopping, find a surge suppressor that's designed specifically for computers, not other electronic gadgets and household appliances. They are usually labeled as such. Also, make sure the strip carries a designation from Underwriters Laboratories as a "transient voltage surge suppressor" (UL-1449).

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That done, look on the package for information about the surge suppressor's capacity to protect your equipment. It's measured in three ways.

First, a suppressor's ability to absorb electrical energy is measured in joules. A higher rating is better. Engineers argue among themselves about how much protection you really need (more protection costs more money), but for valuable equipment, a 600- to 700-joule rating is the minimum.

Second, look for the clamping voltage - the minimum voltage at which the MOVs kick in. In this case, lower is better. Most experts recommend the lowest of the three UL ratings, 330 volts; stay away from those higher than 400 volts.

Third, look for the response time, measured in nanoseconds. Lower is better here, too - less than one nanosecond if possible.

In addition, look for a power strip with two indicator lights - one showing whether the power is on and the second showing whether surge protection is still active. If the protection light goes out, the strip will still provide electricity, but won't help when there's a spike.

Also remember that electric outlets don't present the only danger to your computer. Surges can also reach sensitive equipment through phone, network and cable lines. The most versatile surge suppressors include ports for phone (RJ11), network (RJ45) and coaxial cables. They also require extra cables - one plugs into the suppressor and another leads from it to your equipment.

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To keep your computer running during brief outages or give it time to shut down during blackouts, an uninterruptible power supply (UPS) is worth the additional money.

In addition to the features of a good surge suppressor, it adds a battery backup that kicks in automatically when it senses a power drop and provides a steady source of conditioned electricity to your system.

The capacity of UPS units is measured in Volt-Amps. How long juice lasts depends on how much you're willing to pay, and how much equipment you plug in. Most computer stores have a chart to help determine the right unit for your system.

You'll find UPS units for as low as $80, but to keep a single computer and monitor running for as long as 20 minutes, expect to pay $100 to $150.


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