A surge protector is a piece of equipment that
protects electrical devices from power surges. A power surge is an
increase in the voltage, or “electrical pressure,” in an electrical circuit.
Surges can be caused by lightning strikes, everyday activity on your local
power grid and even the cycle patterns of high-energy appliances, like
refrigerators and air conditioners. Over time, even relatively minor surges
can take a toll on computers and other electronic products, which have more
sensitive components than simple electrical appliances, like lamps or fans.
Surge protectors can also protect larger appliances and power tools from
When voltage jumps to unsafe levels, the surge protector redirects the excess energy away from connected devices. While no device is 100% effective against all surges, adding a surge protector can help extend the life of your electronics, appliances, and tools. This buying guide explains how to choose a surge protector, so you can feel confident in choosing the right level of protection for your needs.
Factors to Consider:
Most surge protectors use MOVs, a type of variable resistor. MOVs are resistant to low-voltage current, so during normal operation, they won’t conduct electricity, allowing the current to pass directly to the connected device. When exposed to higher voltage, the resistance in the MOV drops, and it begins to direct current away from connected devices. Surges wear MOVs out, so over time, a MOV surge protector will lose its protection abilities.
There are four ways you can add surge protection in your house:
Whole House Surge Protectors
Also called point-of-entry surge protectors, whole-house models are installed at your main electrical panel. These protectors guard an entire household or building from external surges. They also offer some protection against surges generated by appliances within a house or building, but only when those surges reach the main electrical panel. Because they can’t intercept all surges, it’s best to use a whole-house protector in conjunction with point-of-use protectors.
Before installing a whole-house surge protector, read and observe the manufacturer’s instructions and adhere to all recommended safety precautions carefully. Codes and regulations vary greatly, so ensure the project complies with applicable local codes and regulations. If you have any doubts, consult local experts or authorities.
Surge Protector Strips
The most common form of point-of-use protection is the surge protector strip. You plug multiple devices into the strip and plug the strip into a standard electrical outlet. When a surge moves through the electrical circuit in a house or building, the surge protector diverts the energy away from connected electronic devices. It’s important to understand that not all power strips offer surge protection. Only units described as surge protectors or surge suppressors are designed to deal with voltage surges.
Another type of point-of-use device is the battery backup, also known as an uninterruptible power supply (UPS). A battery backup provides instant backup power to connected devices in the event of a power failure. Most battery backups provide surge protection as well. In an online UPS design, connected devices run off the battery at all times. The power from the electrical outlet continually charges the battery, rather than powering devices directly, which further isolates the devices from surges.
Wall-Mount Surge Protector
An alternative point-of-use option is the wall-mount surge protector. These look and function like standard electrical outlets, but they have built-in surge protectors. They provide basic protection in spots where you can’t fit a full surge protector. For example, you might use one of these outlets in your kitchen to protect a microwave from power surges.
Power cords aren’t the only lines that need surge protection. Communication and data cables can also carry surges. For complete protection, look for a surge protector that includes inputs and outputs for each type of power or communications line leading to your electronic devices.
Surge protectors may include protection for:
When you’re considering the type of protection you need, pay attention to how your electronic devices are connected. When multiple devices are wired together—in a home theater or computer set-up, for example—surges can potentially jump from one device to another.
UL 1449 Voltage Protection Rating (VPR) - VPR is a measure of the surge
protector’s let-through voltage, which is the maximum voltage a surge
protector will let through to connected devices. The lower the VPR number, the
better the protection.
UL 1449 Suppressed Voltage Rating (SVR) - SVR is an earlier measure of
let-through voltage, based on a test using 500-amp current. You may see this
rating on some surge protectors, instead of the newer VPR rating. When
comparing SVR to SVR, a lower number usually indicates better protection. The
lowest possible SVR rating is 330 volts.
Joule Rating - The total amount of energy a surge protector is capable
of absorbing over time. A higher joule rating may indicate a longer product
lifespan. Look for a joule rating above 600 for normal household use.
Response Time - How quickly the surge protector reacts to a surge, measured in nanoseconds. The faster the response time, the better the protection. One nanosecond or less is ideal.
Energy Saving Designs
Both surge protectors and ordinary power strips can help you save energy. When you plug certain electronic devices, such as TVs, directly into a wall outlet, they never really “turn off.” Instead, they enter “standby mode” and continue to drain energy. But if you plug these devices into a surge protector or power strip and switch the unit off, the connected devices will not use any power. This can reduce your power bill over time.
Some surge protectors and power strips include features that make saving energy even easier by cutting power to connected devices automatically when the devices enter standby mode or are not in use. There are a few energy saving designs available:
Load sensing plugs can detect the characteristic voltage drop that
indicates a connected device has entered standby mode. As soon as the device
enters standby mode, the plug automatically cuts the power, so the device is
truly off. An energy-saving surge protector might include some load-sensing
plugs and some ordinary “always-on” plugs for devices you don’t want to turn
Master/power save plugs are a variation on the load-sensing system. In
this design, one “master” smart plug controls other “power save” plugs. When
the master plug detects the device connected to it has entered stand-by mode,
it cuts off power to that device as well as the devices connected to the power
save plugs. For example, if you connected a TV to the master plug and
connected other home theater equipment to the power save plugs, you would cut
power to all devices at once just by switching off the TV.
Remote control surge protectors come with a wireless switch that turns
select plugs on and off. You can position the switch on a wall, so that
turning off devices connected to the surge protector is as easy as switching
off an overhead light. This is especially useful when a surge protector is in
a hard-to-reach spot.
Occupancy sensing units cut power to certain plugs when a sensor
detects lack of nearby motion.
Timer surge protectors and power strips can turn on and off at
particular times of day.
Warranties - Coverage of surge damage to any device connected to the
surge protector. Check the warranty to see what it will and won’t cover.
Automatic Warning Devices - Lights or alarms to alert you when a surge
protector needs to be replaced. Surge protection elements wear out over time,
but it’s not always obvious when you need to get a replacement, because the
unit may continue to provide power to connected devices.
3-Line Protection - Protection of all three lines—hot, neutral, and
ground—in an electrical circuit. Because surges can occur on any line,
3-line-protection, also called all-mode protection, is necessary for full
Power Shut Down Protection - An automatic shut-off system that cuts the
power to a power strip’s outlets when the surge protection elements reach
their capacity. This is useful because a massive surge may wear out the
protection elements quickly, leaving connected devices vulnerable to
additional surges before you realize you need to replace the unit.
Resettable Circuit Breaker - An added built-in safety measure that acts
like the resettable breakers in an electrical panel. The circuit breaker shuts
off a surge protector power strip during a sustained power overload, to
protect both connected devices and the surge protector itself.
GFCI Protection - A system that automatically shuts off power when it
detects a short circuit, reducing the risk of electrical fire.
Line Conditioner - A system that continually adjusts the electrical
current coming from an outlet to smooth out relatively minor irregular
fluctuations in addition to actual surges.
Metal Case - A sturdier casing, which can better withstand damage and
Cord Fire Protection - A system that automatically cuts power when a
sensor detects damage to the wire insulation.
Safety Covers - Plastic covers that block plugs when not in use.
Concealed Design - A surge protector that includes a cover that hides cords and plugs, for a cleaner loo