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Lumbermen’s Underwriting Alliance
SURGE PROTECTION
A power surge, or transient voltage, is an increase in
voltage significantly above the standard 120 volts or
240 volts. High voltages from power surges can cause
electronic devices to heat up, like the filament in a
light bulb, and burn. Even if the increased voltage
does not immediately break down the device, it may
put extra strain on the device, wearing it down over
time. When the voltage increase lasts three
nanoseconds (billionths of a second) or more, it's
called a surge. When it only lasts for one or two
nanoseconds, it's called a spike.
Power surges can originate from external and internal
sources. Lightning is an external source. When
lightning strikes near a power line, it can cause an
extremely large power surge. Other external sources
include problems with the utility company's
equipment and downed power lines. While lighting is
a cause, it is actually one of the least common causes
of power-surge-induced equipment failure.
Internal sources include the operation of electrical
devices, such as elevators and air conditioning
systems, which require a lot of energy to turn on and
off compressors and motors. This switching creates
sudden, brief demands for power that upset the steady
voltage flow in a building’s electrical system.
Another internal source is faulty electrical wiring.
While these surges are nowhere near the intensity of a
lightning surge, they can be severe enough to damage
components, immediately or gradually, and they
occur regularly in most building's electrical systems.
A surge protector is designed to protect the sensitive
electronics in computers and microprocessorcontrolled equipment from power surges. A surge
protector is designed to pass the electrical current to
the electrical device plugged into it. When the voltage
surges or spikes the surge protector diverts the extra
electricity into the grounding wire. In the most
common type of surge protector, a component called
a metal oxide varistor, or MOV, diverts the extra
voltage.
There is a wide range of surge protectors available,
both in performance and price. There is the basic $10
- $20 surge-protector power strip, which generally
can handle surges of up to 6,000 volts. This device
will provide some protection, but not from bigger
surges or spikes, or lightning; in such cases, the best
protection is to unplug the device. Another problem
with standard surge protectors is that they can burn
out with one good surge - a protector with a light that
indicates if it is functioning properly is recommended.
Better surge protectors can handle surges up to
20,000 volts and, with the exception of perhaps a
nearby lightning strike, will protect against most
surges. These systems can cost tens of thousands to
hundreds of thousands of dollars.
Underwriters Laboratories Inc. (UL) has a listing
program for surge protectors. A device should be
listed as a transient voltage surge suppressor, which
means that it meets UL 1449, Standard for Transient
Voltage Surge Suppressors - this is UL's minimum
performance standard for surge suppressors.
Another alternative is a surge arrestor. These are
installed near the electric meter, where the power
lines enter the building. They are designed to protect
equipment from external power surges; however, they
won’t protect from power surges that originate
internally.
AN-6200 (06/10)
(COPYRIGHT ©2004, ISO Services Properties, Inc. [email protected])
The information in this article was provided courtesy of Lumbermen’s Underwriting Alliance.
www.lumbermensunderwriting.com
For further information please contact your servicing Loss Prevention Representative, thank you.