Electrical Surges and Spikes

From the Series: "Home Construction & Maintenance in Mexico"

By J. Brad Grieve, P.Eng. MBA © 2007
His Web Site

Surge protectors use a variety of techniques and strategies.

We see them in just about every house here at Lake Chapala. Sometimes they are humming and others quietly sit in a corner, showing a little light on. But all are on guard, protecting our electronic devices. They are our electrical surge protectors and they come in various sizes and forms. They are serving an important purpose and act as a little insurance in case of an attack of abnormally high voltage unknowing entering the outlet used by your computer, etc.

First, let's understand a "surge" is when the voltage rises above normal levels for more than three nanoseconds (billionth's of a second) and a "spike" is when it only rises for one or two nanoseconds. Voltage is the measure of potential electrical energy or, to use the analogy of water flowing in pipes, voltage is similar to the water's pressure. Modern electronic devices that have small electronic parts have less capacity to handle voltages above 120 volts and can be damaged by even a simple "spike" or wear out sooner by repeated "surges" in the voltage. Unfortunately, from my research here at Lake Chapala, I have found that the voltages in homes are typically higher than the standard 120-volts. By Federal Law, the Comisión Federal de Electricidad (CFE) must deliver to your home safe electricity that is within a 10% error band of the standard 120-volts. This means that, legally, the voltage cannot be lower than 108 volts or higher than 132 volts. While I have observed normal voltages as high has 140 volts, the majority of homes are in the range of 124 to 132 volts.

 

Surge protectors use a variety of techniques and strategies. Some will use a transformer to help provide a steady conditioned electrical source that is normalized and uncontaminated by unusual frequencies of stray sources. Many protectors will use a type of Metal Oxide Varistors (MOV), which are semiconductors that have an electrical resistance inversely related to the voltage, hence the higher the voltage, the lower the resistance. To use the same analogy of water flowing in pipes, an MOV acts like a pressure sensitive valve that opens when the pressure is too high.

Similar to the MOVs, some surge protectors use a gas discharge arrestor or gas tube. . .

Brad Grieve has much more to say about electrical surges and spikes. For information on other surge protectors and UPS units, we invite you to join our family of subscribers... it isn't expensive. A monthly subscription is just $5.00 USD - that's $1.15 per week. An annual subscription costs $30.00 USD - only $2.50 per month or 58 cents per week. We think you'll find it's money well spent.
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