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 power surge/spike?
A:
Most of the damage caused by over voltage “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 adapter?
A:
No. Your surge protector must be directly plugged into a three-pronged grounded outlet. If you use an adapter the warranty will be void and you are not protected.

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 post 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.