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Line Noise

What is it?

The term "line noise" refers to random fluctuations-electrical
impulses that are carried along with standard AC current. Turning on
fluorescent lights, laser printers, working near a radio station, using a
power generator, or even working during a lightening storm can all
introduce line noise into systems.

What can it do?

Line noise interference can result in many different symptoms depending on
the situation. Noise can introduce glitches and errors into programs and
files. Hard Drive components can be damaged. Televisions and computer
screens can display interference as "static" or "snow,"
and audio systems experience increased distortion levels.

What can be done?

Surge suppressors, Line conditioners and UPS units include special noise
filters that remove or reduce line noise. The amount of filtration is
indicated in the technical specifications for each unit. Noise suppression
is stated as Decibel level (dB) at a specific frequency (kHz or MHz). The
higher the dB, the greater the protection.

Be wary of "surge/noise suppressors" that don’t provide this
information. Some surge suppressors (Such as the Tripp Lite Isobar
suppressors) take noise suppression to a new level with Isolated Filter
Banks. These special banks prevent line noise generated from one device
from traveling through the surge suppressor to interfere with other

Using a laser printer (a notorious source for line noise) connected to the
same suppressor that powers a computer will not endanger the computer.