With the start of the spring storm season, it is a good time to consider how well protected the electronics and appliances in your house are from electrical surges and sags. Either condition can permanently damage computer equipment and appliances, which can cost the homeowner several thousand dollars, or create an insurance claim. So I think it is worth taking a second look at how your home is set up before the next round of severe weather strikes.
A sag, or brownout, is a drop in voltage that can last for a few nanoseconds or indefinitely. This can come from several sources such as several appliances on the same circuit cycling on after loss of utility power, a protective utility recloser switch operating due to a lightning strike, lighting damaged transformers/utility conductors, or internal wiring weaknesses within the building. Some less-sensitive appliances in the kitchen or laundry room may stop working momentarily and/or stop completely. The homeowner then has to reset the clocks and controls on these appliances. But for PCs and other home electronics that utilize delicate parts such as hard drives and motherboards, the results can be fatal. If a power interruption occurs before the hard drive has a chance to write the information being entered on the computer, files may become corrupted or lost.
Next we’ll look at surges. A surge is a sudden overvoltage condition that can lasts for a few nanoseconds or several seconds. Surges travel through the electric, phone and CATV lines and can be caused by several events: Several appliances on the same circuit may cycle on and off, causing voltage to fluctuate. Lightning strikes on utility devices may pass high voltage through your home’s wiring. Sometimes this may mean a difference of only a few volts, but it can damage circuit boards, wiring, hard drives, power supplies, and anything else in its path. Lightning is especially nasty for several reasons:
- Lightning can deliver as much as one billion volts and 20,000 amperes of electricity.
- Lightning can travel through telephone and cable lines, which have less resistance than power distribution lines- this is generally what destroys computers, telephones and televisions.
- Lightning can arc through resistors, surge suppressors, and fuses, and through nearby equipment causing equipment fires.
It pays to take steps to protect your equipment now, and especially if you experience a lot of stormy weather. There are some products that you can install that are designed to protect appliances that rely on AC power:
Surge suppressor: These come as simple block-shaped devices that plug directly into the wall with a single outlet on the exposed side or as power strips that have a heavy-duty cord and a bar with as many as 10 plugs on it. These devices are designed to stop the high voltage surge and self-destruct when one occurs in order to prevent the current from traveling into the devices plugged into the cord.
Uninterruptable Power Supply (UPS): These devices have the built-in surge suppressors as described above and also contain a battery that can be used to compensate for loss of utility power or sags. Some UPS models can power a PC for 5 minutes or longer, depending on the PC power requirements and battery size. Some UPS unit are also equipped to take the incoming utility (or portable generator) power and remove harmonic distortion or transient power issues thereby supplying “clean power” to the sensitive electronic device.
Whole House surge arrestor: This device is hard-wired into the circuit breakers or main electrical panels to protect all electric circuits in the home from a power surge. You can also get similar arrestors installed for your incoming phone and CATV lines. Home owners interested in a portable electric generator to power their homes after a power outage are strongly encouraged to select a generator rated for producing “clean power” or provide protective devices on individual appliances to guard against generator surges.
Lightning Protection System: These kits consist of lightning rods placed on top of the house that carry the electrical charge down through cables, away from the house and into the ground so that the home and its occupants are not harmed by the strike. Even though these are not a 100% guarantee that your home won’t incur lightning damage, your chances of it happening are greatly reduced. This type of installation should be left to a professional however, as an incorrect installation could be disastrous.
Given the fact that lightning can still defeat some of even the best protective devices, shut down and unplug your sensitive electronic devices if severe weather threatens. Please remember that on some items like PCs, phones and televisions you have to unhook the incoming phone or CATV line as well. Without being physically connected to the grid, this will ensure their safety.