• Megan Connor

Can a surge protector protect against lightning?

Updated: Oct 11

Was the item connected to a surge protector? Certainly, this is a valid question, but what protection can surge devices, including surge suppressors, UPS battery backup devices, and power conditioners, actually offer when lightning is involved?

In this article, we will take a deep dive into surge protectors, their ability to protect against lightning, and what steps you can take to shield your computers, home theater systems, and even appliances from the harmful effects of surge damage.

lightning strike damage power lines storm weather power surge lightning surge electronics


How do surge protectors work?

Surge protectors offer many benefits, not least of which is the ability to connect multiple electronic devices to a single outlet. When connected to a standard outlet, a surge protector will distribute voltage through the receptacles and subsequently the connected electronic devices. When too much voltage is detected, the surge protector will divert the excess voltage, thereby preventing potential surge damage to the connected devices.

Many surge protectors are known as parallel circuit surge protectors. There are different types of parallel circuit surge protectors, but all function to divert incoming excess voltage to the ground and thus away from the primary circuit. Some surge protection devices utilize internal fuses or other internal ‘fail-safes’ intended to stop electricity not diverted by the initial mechanism, though this is not universal.

Unlike parallel circuit devices, a series circuit surge protector works by slowing incoming voltage rather than transferring the excess voltage to a separate circuit.

Internal components of a surge protector lightning damage electronics inspection
Internal components of a surge protector

All surge protectors have a joule rating. The joule rating indicates the amount of excess voltage a surge protector can absorb before failure. When the incoming voltage exceeds the joule rating, electrical damage may occur to the connected devices, such as computers and home theater equipment, like receivers, amplifiers, and media servers.

Depending upon the source of the power surge, and the intensity of the surge in terms of duration and voltage or current, varying damages may occur to the connected electronics, from internal circuit board failure to visible external degradation like melting, scorching, or even a combustive reaction. A joule rating spectrum of as little as 200 joules to as much as 4,000+ joules is available in the current surge protection device market.

power adapter lightning damage surge protector failure
Damage to a power adapter connected to a surge protector

Surge protector vs power strip

The terms surge protector and power strip are often used interchangeably; however, there are key differences you’ll want to understand before connecting valuable devices.

A power strip WILL NOT protect a connected device from a power surge from any source, let alone a lightning-related surge. A power strip serves only to increase the number of devices that may be safely connected to a single electrical outlet. Power strips are convenient devices and can function as extension cords in a variety of settings and applications. Power strips are commonly used in outdoor lighting, entertainment centers, and home offices.

If you want to be sure your devices are protected from potential surges, do not use a power strip alone. In fact, items connected to a power strip may sustain electrical damage when a voltage spike occurs, even if the power strip is turned off.

EXPERT TIP: When a thunderstorm is headed your way, disconnect the power strip from the wall outlet completely. Simply turning off the power strip will not protect your devices from potential surge damage.

Are surge protectors effective?

Well, yes and no.

For lower voltage surges, such as those caused by circuit overload, surge protectors should work as designed. Parallel circuit surge protectors will divert the excess voltage and prevent electrical damage to connected electronic items. Series circuit surge protectors will slow the incoming voltage, similarly lowering the risk of surge-related damages.

For high-voltage surges, the joule rating of your surge protector becomes imperative. The higher the rating, the greater capacity of the surge protector to shield connected devices from electrical damage. High-joule-rated surge protectors will be able to better protect items against power surges caused by weather, damages to power lines, and other utility-related issues.

To determine what level of protection your electronic device requires, you will want to consider the item's value and data storage capacity. Higher-end electronics that store a significant amount of data, like custom-built computers, high-quality televisions, and home theater equipment, will benefit from a greater joule rating. A toaster or lamp, for example, demands much less from a surge protector.

Recommended joule ratings for common electronics:

Six factors to consider for surge protector efficacy

1. Joule rating - The amount of energy the unit can absorb before damage occurs.

2. Clamping voltage - Threshold at which the unit will begin diverting electricity from the main circuit, typically between 330V and 400V. Higher thresholds can allow the transmission of damaging voltage to connected devices.

3. Response time - Length of delay between surge detection and surge suppression. Different surge protectors will have different response time ratings. Even one nanosecond might be long enough of an exposure to high voltage to fry sensitive circuitry.

4. Age - Surge protectors degrade over time. Regular replacement is key to continual protection.

5. Previous surges or power outages - Joule rating is cumulative. If a surge protector has taken many previous minor power surges, its effectiveness may be severely reduced or entirely nullified.

6. Type of power surge - A good surge protector should be able to adequately suppress minor power surges; however, higher voltage surges will likely prove problematic.

Will a surge protector protect against lightning?

The Short Answer? No.

High-end surge protectors may be able to protect against 4,000 joules, but a single direct lightning strike carries between 1 and 10 billion joules of energy. In the case of lightning surges, surge protectors will become overloaded and thus offer little to no protection.

Surge protectors and appliances

Surge protection devices for appliances function similarly to the surge protectors we've discussed in this post so far. Single outlet surge protection devices are available to simply plug into an appliance outlet; however, as many appliances, such as full-size refrigerators, wall ovens, and ranges are on dedicated hardwired circuits, an alternative surge protection strategy is needed.

Whole home surge protectors installed at the main service panel will aid in protecting the entire electrical system of the residence. While these devices offer some peace of mind, whole home surge protectors are limited in the ability to defend against damage from lightning. As previously mentioned, lightning surges carry an ENORMOUS amount of energy that can fry a surge protection device easily. All appliances subjected to a potential lightning surge should be evaluated to address any possible damages.

scorching power range appliance electric cooking circuit board lightning power surge claim inspection
Circuit board for electric range damaged from lightning

Do I really need a surge protector?

In this post, we have learned how surge protectors work and which factors contribute to the efficacy of a surge protector. While surge protection devices offer little protection against lightning, when used properly, surge protectors can safeguard your electronics and appliances from other sources of voltage spikes, such as those due to circuit overload, weather, power line failure, or other utility-related issues.

To lower the risk of surge damage to your electronics and appliances, connect your valuable devices to a properly rated surge protection device. Remember, even if a surge protector was in use at the time of a surge event, all connected items should be inspected to address potential internal damages, fast!

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