Use Surge Protection to Keep Electronics Safe

Whether from lightning or line noise, these surge protection devices can block voltage spikes that would otherwise damage your sensitive electronic equipment.


| September/October 1984



three surge protection devices

Depending on your equipment, you can employ one of three devices. The cylindrical unit in the middle is a stock part; the other two are modified. The six outlet block at left (aka "Better") has metal-oxide varistors (MOVs) for surge protection. The power strip (aka "Best") uses MOVs, RF chokes, and capacitors for both surge protection and line filtering. Both of the modified devices use MOV protection between hot and neutral lines and between both legs and ground for full isolation from voltage transients.


Photos by MOTHER EARTH NEWS Staff

"Snap, crackle, pop" may be familiar breakfast sounds to some people, but for many others, such noises signal disaster — lightning disaster.

Each year, the damage done by lightning runs into the millions of dollars, and the human casualties number in the thousands. As a matter of fact, more people are killed each year by this form of electric discharge than by all other natural disasters combined.

Lightning wreaks the most financial havoc, however, when it damages electronic equipment. Stereos, televisions, and home computers succumb to the effects of this force daily. And the most perplexing part of the problem is that lightning doesn't even have to strike an appliance directly to inflict damage. Flashes many miles away can turn hundreds or thousands of dollars' worth of circuitry into high-tech junk.

Voltage Surges

The problem comes from the utility-fed electricity used to run your equipment. The power delivered to your home has probably traveled through hundreds of miles of wire and several substations before it reaches you, yet encounter no surge protection measures along the way.

When lightning strikes, it does so with the force of millions of volts. You can actually hear lightning discharge several miles away (and I don't mean the thunder) if you listen to an AM radio during a thunderstorm. The high-voltage discharge generates radio waves that are picked up by your radio's antenna.

In a similar fashion, the sprawling utility grid can pick up static from lightning. When a strike comes close to a power line, the wires act as a large antenna and absorb part of the energy. A power surge as high as 2,500 volts can be injected into the grid in this manner. These voltage surges travel down the wires into your home and right into appliances, where they can destroy sensitive electronic parts — even when the equipment is turned off.





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