Do I Need A Surge Protector?
A standard surge protector passes the electrical current along from the
outlet to a number of electrical and electronic devices
plugged into the power strip. If the voltage from the
outlet surges or spikes -- rises above the accepted
level -- the surge protector diverts the extra
electricity into the outlet's grounding wire.
In the most common type of surge protector, a
component called a metal oxide varistor,
or MOV, diverts the extra voltage. A
MOV forms a connection between the hot power line and
the grounding line.
As soon as the extra current is diverted into the MOV
and to ground, the voltage in the hot line returns to a
normal level, so the MOV's resistance shoots up again.
In this way, the MOV only diverts the surge current,
while allowing the standard current to continue powering
whatever machines are connected to the surge protector.
Metaphorically speaking, the MOV acts as a
pressure-sensitive valve that only opens when there is
too much pressure.
Q: What is a Joule (usually pronounced “jool")?
A: Is a measurement of energy (1 joule equals one
watt-second). The joule rating of your surge protector
is based on the number of MOV's (metal oxide varistors)
inside the protector. A higher number of joules should
equate to a higher ability to absorb spike or surge
energy. Each MOV has a rating and when you add these all
up you get the total number of joules.
Q: What is Power Blocker?
A: MOV's (Metal Oxide Varistor) may degrade over
time and use, especially if they are absorbing energy
near or exceeding their ratings. Even when the MOV's are
no longer protecting, most surge protectors continue to
provide AC power which may result in potential damage of
your connected equipment. Power Blocker surge protectors
shut themselves down once they have exceeded capacity so
equipment is not exposed to further surges.
Q: What is Clamping Voltage?
A: Clamping voltage is the amount maximum voltage
allowed to pass through the circuitry to the connected
equipment when tested with the UL test surge. 330 volts
is the lowest rating allowed by UL and the rating must
be stated on the unit. Other allowed ratings are 400,
600, 800and 1000 with the lowest being better. Some
manufacturers use a rating called "let through voltage"
to present appearances of superior performance but UL
does not validate this terminology.
Q: What is a surge/spike?
A: Most of the damage caused by overvoltage "power
events" is caused either by longer duration high-voltage
transients (surges) or shorter-duration transients
(spikes) entering via the power mains. Surges and spikes
can reach 3000 to 6000 volts.
Q: Outlets aren't grounded, can I use an
A: No. Your surge protector must be plugged directly
plugged into a three-pronged grounded outlet. If you use
an adapter the warranty will be void.
Q: Can I daisy chain surge protectors?
A: No. Surge protectors must be plugged directly
into a grounded outlet to work properly. (Underwriters
Laboratories prohibits daisy chaining)
The newer and better surge protectors have indicator
lights showing that the protection is active. This is
important since the MOVs do wear out, so you know when
you have to replace the unit.
Next month I will explain battery Back-up,
Uninterrupted Power Supply (UPS). A UPS can keep your
computer and electrical equipment operating in case of
brown-outs or power outages.