5 Causes of Power Surges and How to Protect Your Property

What exactly is a power surge?

At the simplest level, a power surge happens when the voltage in an electrical circuit spikes to a higher level than the circuit was designed to handle. A little bit of basic electrical theory will show why this is so dangerous.

The United States uses 120v AC for mains power. The AC stands for alternating current. This means the electricity moves in a sine wave pattern. The 120 volt label is actually an average, and the waves crest at 169 volts. Electrical systems, then, are built with the assumption that the voltage in the lines will never exceed 169 volts. Everything from the tiny printed circuits in computers to 20th Century electromechanical parts in radios and many older appliances are designed to safely operate within the assumption that the power from a wall outlet won’t exceed 170 volts.

When a surge of power exceeding the design goes through the system, the miniature wires and contacts in computers and televisions overheat and can literally fry computer chips in a puff of acrid smoke.

Larger-scale components like wall outlets can’t handle the surge either, since the surge of electricity will exceed what the wires can carry. Following the path of least resistance, the surge can cause arcs to nearby metal surfaces, short-circuiting appliances or even starting a fire.

What Causes Power Surges?

External Causes

Lightning Strikes

Electrical storms are a common and destructive cause of power surges. Lighting follows the path of least resistance–and that’s usually the power grid, designed to move electricity as efficiently as possible.

The glass insulators and inch-thick wires of an electrical substation can usually withstand an errant lightning bolt. Your home appliances aren’t so lucky. If a lightning bolt strikes the power lines near your house, millions of volts will temporarily surge through lines designed to carry 120. Unprotected circuits will be fried instantly.

Power Outages

Power going out with no warning can be dangerous in its own right to digital devices. But what usually does the most damage is when the power comes back on. Whether its a backup substation or an emergency generator kicking in, power comes back as a jolt before the sine wave evens out again. Delicate electronics are especially at risk.

Internal Causes

Air Conditioners

Have you ever noticed on hot summer evenings that the lights dim for a second when the A/C blower kicks in? That’s a power surge at work. While not as dramatic as lightning or a power outage, the same process is happening-the sudden demand for power causes a voltage drop, then followed by a surge while the system normalizes.

Power Tools

Shop tools like table saws and heavy lathes can cause surges just like air conditioners. If they trip a circuit breaker, they can cause a temporary power outage.

How to protect your home from power surges?

  • Unplug what you’re not using.

It’s a simple fact that a product can’t be hit by a power surge if its not plugged in to mains power. For sensitive and valuable equipment that isn’t frequently used, unplugging it is a cheap option. This won’t actually protect your electronics from power surges, but it will keep them from being exposed to power surges.   

  • Buy some surge protectors.

You can buy power strips or outlet covers that have built-in surge protection functions and circuit breakers. These are a good option when you only need a computer or a TV protected, but adding these to every outlet in a home would be prohibitively expensive and a bit of an eyesore. They’re only good for things on an outlet as well, so hardwired lighting and electronic equipment like in-wall speakers can’t be protected.

  • Get Whole Home Surge Protection

The best protection you can get against damaging surges, spikes, and overvoltage is a whole-home surge protector. It takes an electrician to professionally install these devices at your main service panel. These devices protect everything connected to your main breaker box, not just your outlets.

  • Upgrade Old Appliances

Power-hungry air conditioners and refrigerators won’t cause a dramatic overload like a lightning strike, but their continuous power surges can do more long term damage. If your fridge or A/C makes the lights dim when the compressor kicks over, it’s probably placing stress on the more delicate electronics of your home.

Do you have questions about surge protection or other home electrical issues?

The folks at Prime Electrical Services have over 20 years of experience as residential electricians. Whether you have questions about the best way to protect your home from overvoltage, are considering installing new electrical devices, or just want someone to check your home for vulnerabilities, they’re the team to call.