The most serious threat to your computer and other electronics today might not be a virus or spyware attack. It's a summer thunderstorm - or more precisely, the sudden blackouts and power surges that lightning can cause.
If you haven't done anything to protect your equipment against this threat, it's time. And if you haven't checked the protective devices you bought a couple of years ago, it's time for that, too.
Here's why: Most of the components in your PC are designed to operate at 12 volts, 5 volts or even lower levels. Your computer's power supply (which sits just inside the case where the fan on the back can cool it) normally transforms the sizzling, 120-volt AC current in your house into the low-voltage, direct current that your PC needs.
FOR THE RECORD
The address for the American Power Conversion Web site in Mike Himowitz's Plugged In column Thursday was incorrect. It should have been www.apc.com.
The Sun regrets the error.
The power supply can take care of small, normal fluctuations in line voltage. The problem is a sudden spike that can fry the insides of your machine. This is most likely to happen when the voltage returns after a power disruption - and it may happen repeatedly if the electricity comes back, goes out, and comes back again.
But surges can also happen in a home when a refrigerator, air conditioner or some other appliance on the same circuit cycles on. Surges are endemic in some office buildings.
The first line of protection for your PC (or high-definition television, or any expensive electronic gadget) is the surge suppressor. Usually sold in power strips with four or more outlets, these devices divert surges to the ground wire of your home or office. Better units also filter and condition the power to protect your equipment from smaller glitches and burps that can damage it over time.
You can buy a surge suppressor for as little as $8 or spend $75 and up, depending on bells and whistles. The first thing to look for is an Underwriter's Laboratories label certifying the device as a Transient Voltage Surge Suppressor compliant with UL Standard 1449.
Now consider three specifications, all of which should be detailed on the box or label. One is the amount of energy the suppressor can absorb, measured in joules. Look for a minimum of 700 joules. More is better. The next is the clamping voltage - the voltage at which the suppressor starts to do its job. Lower is better. Most experts recommend a maximum of 400 volts. Finally, look for the response time. Again, lower is better - preferably under 10 nanoseconds.
