What is a power surge?

The power flowing through the typical wall outlet is considered 120-volt AC power. The voltage is not delivered at a constant 120 volts, however, and can fluctuate between 0 and 169 volts.

During a damaging power surge, the voltage exceeds 169 volts.

How do power surges happen?

Power surges can originate from an electric utility company during power grid switching. They can also occur if there’s a malfunction in a nearby transformer or transmission line. Some of the most powerful power surges can occur due to a lightning strike.

Surges can also occur within the home. When a high-powered electrical appliance such as an air conditioner or refrigerator turns on or off, a smaller power surge can occur. Because these appliances’ motors and compressors require so much energy to switch on and off, the brief power demand disturbs the steady voltage flow in the electrical system.

How do power surges cause damage?

A boost in voltage above a device’s normal operating voltage can cause an arc of electrical current within the device. The heat that is generated as a result can cause damage to the electronic circuit boards and other components within the device.

Major power surges, such as those stemming from lightning strikes, can cause permanent damage in an instant. But smaller surges, like the ones that occur when your air conditioner cycles on, can cause unseen damage in tiny increments that accumulate over time. They may not disable an appliance in one shot, but they can shave years off the functional life of any device.

What are the signs of a power surge?

There are a few signs that may indicate your appliance or device experienced a power surge:

• The device’s clock or lights are flashing
• The device is off or does not work
• There is an acrid, burnt odor around the device or power source
• A surge protector or power strip may require resetting

How to prevent a power surge from damaging your appliances and electronics

You can’t prevent what happens outside your home, but you can protect what’s on the inside. Purchasing a quality surge protector, also called a surge suppressor or surge diverter, can help protect your home from damage caused by power surges.

A surge protector diverts voltage spikes safely to the ground rather than letting it enter the sensitive circuits of your appliances or equipment.

Choosing the right kind of power surge protector

The type of surge protector you choose will depend on how you’re going to use the surge protector and what you can afford.

• Whole-house surge suppressors, or panel-mounted surge suppressors, connect directly to your home’s fuse box and prevent power surges from entering your home at the source. Cost is determined by the suppressor’s power capacity, rated in joules, but can run from $50 to several hundred dollars.
• Power strips with surge protection are the most common and affordable type of surge protection available. Surge protected power strips are rated in joules, so it’s important to choose a model with the appropriate rating for the appliances you’re protecting. Inexpensive surge protectors run between 400 and 600 joules and higher-end protectors are rated at 1,000 or more. Not all power strips have surge protection abilities, so shop carefully.
• Transient Voltage Surge Suppressors (TVSS) are hardwired directly into one of your home’s outlet boxes and can provide excellent protection for anything plugged into them. Various models will provide different levels of clamping (300–400 volts) and capacity (290–900 joules). They come with a light or alarm to indicate a power surge has occurred. While they will continue operating after a surge, their capacity may be reduced. The average cost ranges from $25 to $100 depending on capacity, amperage, and lights/alarms.

Don't wait for lightning to strike. Install or purchase a surge protector today.