Power Surges

What is a Power Surge?

The power you get from the wall outlet is 120 volts of alternating current, also known as 120 volts AC. The power companies try to keep that voltage uniform. Lightning, short-circuits, poles knocked down by cars, or some other accident can make the voltage jump to hundreds, even thousands of volts.

If the voltage runs above normal levels it is what engineers call a "surge." A surge will last only a few millionths of one second (the "blink of an eye" is thousands of times longer than the typical surge). It is enough to upset your appliances or even destroy them.

What can a Surge Do to Your Appliances?

Your appliances are designed to run on the normal 120 volts AC supply, with some tolerance for more or less, but they can be damaged, or their controls can be upset by surges. The result is then frustration and repair bills, and even a fire in rare cases.

You can do something about it. Your electrician can help and even the power company can offer help.

Other Disturbances and What They can do to Your Appliances

In the normal operation of a power system, unavoidable disturbances other than surges also happen. They can upset electronic appliances, but are unlikely to cause permanent damage.

Some examples of disturbances that can affect your appliances and what damage they can do:

  • Sag - A sag happens when the voltage falls below the normal voltage level for a short time. Sags are unlikely to damage most appliances, but they can make a computer crash, confuse some digital clocks and cause VCRs to forget their settings.
  • Swell - A short duration increase in the line voltage. This disturbance might upset sensitive appliances, and damage them if it is a very large or very long swell.
  • Noise - Noise is a catch word sometimes used to describe very small and persistent disturbances. These do not have damaging effects but can be a nuisance.
  • An Outage - The ultimate disturbance - no voltage at all.

These disturbances are different from surges, but they should be mentioned because the remedies are generally different.