Practicing the Black Art (10/03)
Choosing a Surge Suppressor
by Vinny La Bash, vlabash@home.com
Member of the Sarasota Personal Computer Users Group, Inc.
Let's start with some basics. Standard voltage in the United States is 120 volts. You can think of voltage as a measure of electrical pressure; the higher the voltage, the higher the pressure. It's similar to water pressure that makes water flow through a pipe or a hose. Voltage or electrical pressure is the force that makes electricity flow through a circuit. A sudden, temporary increase in line voltage above 120 volts has the potential to do serious damage to electrical devices.
If a sudden increase in voltage lasts for one or two nanoseconds, it's called a spike. If the increase lasts for three nanoseconds or longer, it's called a surge. A nanosecond is a billionth of a second. How short a period of time is a nanosecond?
Admiral Grace Hopper, developer of COBOL and the first computer compiler, used to use a piece of fiber optic wire in her lectures and speaking engagements to demonstrate a nanosecond. Light travels at about 186,000 miles a second. Her piece of fiber optic wire measured about 18 inches, which illustrated how far light can travel in one nanosecond.
Without getting too deep into technical issues, spikes and surges create excess heat within electrical circuits. If the surge or spike is high enough, it can cause severe damage to electronic equipment. Anything electrical can be fried, from a large mainframe right down to your toaster.
A standard surge suppressor works by diverting power during a spike or surge to the outlet's ground wire. Lightning is the most familiar cause of power surges and gets the most attention because its results tend to be spectacular. In a lightning storm your surge suppressor is likely to be toasted along with anything connected to it. Your best protection is to unplug everything for the duration of the storm.
Surge suppressors are far from useless, but you should understand their capabilities along with their limitations. They are designed to protect you from common causes of line voltage fluctuations. Air conditioners, refrigerators, toasters, and blow driers are the most common sources of spikes and surges generated in the home. You can be affected by faulty wiring, downed power lines or even problems with your utility company's generating and transmission equipment. Because of the sheer complexity of power generation and distribution, power surges are unavoidable.
So why didn't we need surge suppressors 50 or 25 years ago? It is only recently, relatively speaking, that modern electronic devices such as computers and TV sets became controlled by small delicate circuits that are sensitive to surges. Microprocessors can function properly only when line voltage is correct and stable.
What kind of equipment should be protected by a surge suppressor? The short answer is anything that plugs into a wall outlet that is controlled by a microprocessor. That includes, but is not limited to, computers, TV sets, DVD players, and most home entertainment components. If it's expensive to replace, it makes economic sense to protect it with a surge suppressor.
Broadband modems, telephone equipment, and cable TV systems also require protection from voltage spikes and surges. Your surge protector should have phone line input jacks, and if you have equipment hooked up to coaxial cables, look for a cable surge protector.
Be aware that there are three levels of surge protectors:
The Basic Power Strip Strip:
This equipment is characterized by low price, up to six outlets, and rarely phone or cable outlets. It offers very limited protection.
The Surge Station Station:
These are physically much larger units offering superior protection and in most cases, line conditioning. They feature internal circuit breakers and protection for phone and cable equipment.
Uninterruptible Power Supply (UPS) UPS):
These devices have all the capabilities of a surge station plus battery backup in case of a power failure. This lets you to shut down your equipment normally and greatly reduces the chances of lost data or damaged equipment. High quality units filter out noise from your power lines and provide the highest level of protection.
Here's what to look for when shopping for a device:
Clamping Voltage Voltage: This is the point at which the device starts shunting voltage to the ground line. The lower the clamping voltage, the better protection you have. Look for an Underwriters Labs (UL) rating lower than 400. If there is no UL label, move on to the next candidate.
Energy Absorbtion/Disapation Disapation: This tells you how much punishment the unit can take before failing. The rating is measured in joules and you want a high number. Most homes can get along with a rating of 200 to 400 joules. Units which can absorb 600 joules or more tend to be expensive, but they are worth the money if you need the protection.
Response Time Time: This is the time the unit needs to respond to a voltage surge. You want a unit that can respond in less than a nanosecond.
Indicators Indicators: Look for indicator lights that will tell you if all components are functioning.
This article is hardly the last word on surge suppressors and Uninterruptible Power Supplies. However, you should now have a basis to find the kind of unit you need for your particular circumstances.
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Copyright 2003. This article is from the October 2003 issue of the Sarasota PC Monitor, the official monthly publication of the Sarasota Personal Computer Users Group, Inc., P.O. Box 15889, Sarasota, FL 34277-1889. Permission to reprint is granted only to other non-profit computer user groups, provided proper credit is given to the author and our publication. We would appreciate receiving a copy of the publication the reprint appears in, please send to above address, Attn: Editor. For further information about our group, email: admin@spcug.org/ Web: http://www.spcug.org/
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