Surge Protectors

Computers and home electronics rely on solid-state circuits and microprocessors. While these devices are small and powerful, they are also extremely vulnerable to power surges or spikes. A power surge, or transient voltage, is an increase in voltage significantly above the designated level in a flow of electricity. These power surges can shut down equipment, cause a loss of memory or damage internal circuitry.

The most obvious cause of power surges is lightning. Other causes include downed power lines and other problems with the electrical distribution system. The most frequent surges actually originate within the home. Appliances like air conditioners and refrigerators require a lot of energy to turn on compressors and motors. This creates sudden, brief demands for power, which upset the steady voltage flow in the electrical system. While these surges are nowhere near as powerful as a lightning surge, they can be severe enough to damage components, either immediately or gradually over time. Even when power surges don't result in obvious damage to equipment, over time they take their toll and can eventually cause equipment failure.

You can protect your computers and home electronics by installing surge protectors. A surge protector is a device that re-directs power surges through an alternate path of least resistance (or to "ground"), protecting valuable electronic equipment. Surge protectors should be installed on any equipment that contains a microprocessor. Surge protection devices are available for microwaves, refrigerators and other household appliances, televisions, VCRs, stereos, phones and fax machines, and personal computers and accessories. Some surge protectors have a line-conditioning system for filtering out "line noise", smaller fluctuations in electrical current.

Telephone and cable lines can also conduct high voltage -- for full protection, you should also guard against surges through your telephone or cable lines.

The voltage spike from a lightning strike will overwhelm most surge protectors. For the best protection, devices like computers and electronics should be unplugged during lightning storms.

Types of Surge Protectors

There are a wide variety of surge protectors available. Aside from the standard "power strip" type, there are also single-outlet plug-in models for protecting one or two devices. Larger units, sometimes called "surge stations" fit under your computer or on the floor and provide better voltage protection and line conditioning. Most also have inputs for phone lines and cable modems.

Whole-house surge protectors are also available. These devices connect to the main electrical panel and protect against lightning and power line surges from outside the home. They don't protect against surges caused by other appliances in the home, so sensitive electronics and computers should also have their own surge protection.

An Uninterruptable Power Supply (UPS) combines surge protection with a battery back-up power source. When the main power is interrupted, the UPS switches over to battery power - this allows time to safely shut down the computer. Some models include software that automatically powers down your computer safely without loss of important data.

What to Look For

When purchasing surge protectors, always look for the Underwriters' Laboratories (UL) label and check for the following ratings:

Clamping voltage - the voltage that will activate the surge protector - the lower the clamping voltage the better the protection. Look for a unit with a clamping voltage of no higher than 400V.

Energy absorption/dissipation - how much energy the surge protector can absorb before it fails. A higher number indicates greater protection. Look for a protector rated at a minimum of 200 - 400 joules. For better protection, look for a rating of 600 joules or more.

Response time - the length of time it takes for the surge protector to respond to a surge. Look for a surge protector that responds in less than one nanosecond.

Filtering - the ability to remove interference from electromechanical or radio frequency sources.

Also look for a unit with a performance warranty - if the device fails to protect your computer or electronics, the company will replace them. For very expensive home electronics or computer systems, make sure the dollar amount of coverage is sufficient.

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