Power surges can damage computers, monitors, networking equipment, and other electronics in a matter of seconds. While you can't prevent every power disturbance, you can reduce the risk by using the right surge protection and taking a few basic precautions.
For most home computer setups, start with a properly rated surge protector from a reputable manufacturer. If you need protection during power outages as well as against surges, consider a uninterruptible power supply (UPS). For broader protection, a whole-home surge protective device can be installed at the electrical panel by a qualified electrician.
Understanding how these options work can help you choose the right protection for your computer and other electronics.
What is a power surge?
A power surge is a brief increase in electrical voltage that can damage electronic equipment. Surges can originate outside your home, such as from utility switching or lightning, or inside your home when large electrical loads switch on or off.
The normal voltage supplied to a typical U.S. household outlet is about 120 volts, but a surge can temporarily raise the voltage well above its normal level. The size and duration of a surge can vary considerably.
NIST research on electrical surges notes that surges can occur throughout electrical systems and that appropriate surge protection can help reduce the risk and severity of equipment damage.
What causes power surges?
Common causes include:
- Lightning: Nearby lightning strikes can introduce significant electrical surges.
- Utility switching: Changes in the electrical grid can produce transient voltage events.
- Large appliances: Equipment such as air conditioners, refrigerators, and power tools can create electrical disturbances when motors start or stop.
- Electrical problems: Faulty wiring or other problems with an electrical system can create unsafe conditions.
- Power restoration: Electrical conditions can fluctuate when power returns following an outage.
Not every electrical disturbance is the same. A surge protector is designed to address transient overvoltage events, while other power problems may require different equipment.
How can a power surge damage a computer?
Computers contain sensitive electronic components that can be affected by abnormal electrical conditions.
A sufficiently large surge can cause immediate component failure. Less severe or repeated electrical events may also contribute to component stress or premature failure.
Potentially affected components include:
- Power supplies
- Motherboards
- Storage devices
- Monitors
- Networking equipment
- External drives
- Peripherals
A power interruption can also create a separate problem: data loss or corruption. If your computer loses power while writing data, an unfinished operation could leave a file or application in an inconsistent state.
That's one reason surge protection and regular backups should be considered separate parts of your overall computer protection strategy.
What is a surge protector?
A surge protector is a device designed to protect connected electronics from transient voltage surges.
It may look similar to a basic power strip, but the two are not the same.
A power strip primarily provides additional electrical outlets. A surge protector includes circuitry designed to limit or divert excess voltage before it reaches connected equipment.
Many surge protectors use metal oxide varistors (MOVs) as part of their protection circuitry. The specific protection technology varies by product.
Surge protector vs. power strip
Before buying one, check the product labeling and specifications. Don't assume that a device with multiple outlets automatically provides surge protection.
Look for a product specifically identified as a surge protector or surge protective device, along with information about its protection ratings and applicable safety certifications.
What should you look for in a surge protector?
Surge protectors come with several different specifications. Rather than focusing on a single number, consider the complete product and its intended use.
Joule rating
The joule rating indicates how much surge energy the protection circuitry is designed to absorb before it reaches the end of its useful protection capacity.
In general, a higher joule rating indicates greater energy-absorption capacity. The appropriate rating depends on the equipment you're protecting and the specific surge protector.
Don't treat a particular joule number as a universal minimum for every computer.
Let-through or clamping voltage
Surge protection products may provide a let-through voltage or similar rating that indicates how much voltage can pass through the protective device during a surge event.
Lower isn't automatically better in every circumstance. The rating should be evaluated alongside the product's other specifications and safety certification. NIST notes that surge protection performance involves several factors, including nominal line voltage, surge current capability, and clamping voltage.
Safety certification
Look for recognized safety certification and verify the manufacturer's specifications.
In the United States, UL 1449 is an important standard for surge protective devices.
A certification mark should be associated with the actual product, not simply mentioned in an online product description.
Protection status indicators
Some surge protectors include indicator lights that show whether power is available and whether surge protection is functioning.
These indicators can be useful because surge protection components can eventually reach the end of their useful life.
Circuit breaker or other safety features
Some models include circuit breakers or other protective features designed to help prevent overloads and unsafe electrical conditions.
These features don't replace proper electrical installation or safe use, but they can add another layer of protection.
The best ways to protect your computer from power surges
1. Use a properly rated surge protector
For a desktop computer, monitor, router, printer, and other electronics, use a surge protector that is appropriately rated for the equipment you're connecting.
Choose a reputable product with clearly documented specifications and appropriate safety certification.
Make sure the total electrical load connected to the device stays within its rated capacity.
2. Consider a UPS for critical equipment
A uninterruptible power supply, or UPS, provides battery backup in addition to power protection.
During a power outage, a UPS can provide temporary battery power that gives you time to save your work and shut down your computer safely. Many UPS systems also include surge protection.
A UPS can be particularly useful for:
- Desktop computers
- Workstations
- Home servers
- Networking equipment
- Storage devices
- Other equipment where unexpected shutdowns could cause problems
When choosing a UPS, make sure its power capacity is appropriate for the equipment you plan to connect.
3. Consider whole-home surge protection
A whole-home surge protective device can provide another layer of protection by addressing surges at the electrical panel.
This type of protection requires appropriate electrical installation and should be evaluated and installed by a qualified professional.
Whole-home protection doesn't necessarily eliminate the need for point-of-use protection. Layered protection can be useful because different protective devices address surges at different points in the electrical system.
4. Protect connected equipment
Your computer isn't necessarily the only device that needs protection.
Consider your complete setup, including:
- Monitor
- Printer
- Router
- Modem
- External storage
- Speakers
- Gaming equipment
- Other connected electronics
Also pay attention to equipment connected through other types of cables. Depending on the setup, a surge can potentially enter through power, telecommunications, or other connected lines.
Use protection designed for those connections when appropriate.
5. Back up your important data
Surge protection can reduce the risk of hardware damage, but it isn't a substitute for backups.
Keep important documents, photos, and other files backed up using a trusted backup strategy. For especially important information, consider maintaining more than one copy.
A backup can help you recover your data even if your computer or storage device is damaged.
Surge protection best practices
Installing a surge protector is only part of the solution. Use it correctly to get the most from your equipment.
Plug surge protectors directly into a wall outlet
Follow the manufacturer's instructions for connecting your surge protector.
Avoid using a series of extension cords or connecting multiple power strips and surge protectors together. Overloading electrical equipment can create fire and safety hazards.
The CPSC has warned consumers about faulty and overloaded power strips, extension cords, and surge protectors and recommends using products that meet applicable safety standards.
Don't overload the surge protector
A surge protector may have six, eight, or more outlets, but that doesn't mean you should connect high-power equipment to every outlet.
Check the device's electrical rating and the power requirements of your equipment.
Replace damaged surge protectors
Inspect your surge protector periodically.
Replace it if you notice:
- Cracks or physical damage
- Melted or discolored plastic
- Burn marks
- A damaged cord or plug
- Unusual buzzing or heat
- A protection indicator showing that protection is no longer available
If you're unsure whether a surge protector is safe to use, replace it rather than taking a risk.
Some manufacturers also provide replacement guidance based on the product's age or the number and severity of surge events it has experienced. Follow the manufacturer's instructions rather than relying on a universal replacement schedule.
Don't assume a surge protector lasts forever
Surge protection components can degrade as they absorb surge energy.
Some products include indicators or other mechanisms that signal when protection has been compromised. Check your product documentation and replace the device when the manufacturer recommends it or when the protection indicator shows that it has reached the end of its useful life.
Should you unplug your computer during a storm?
A surge protector can reduce the risk from many transient voltage events, but it isn't an absolute guarantee against every electrical event.
During severe thunderstorms, the safest approach for particularly sensitive or valuable equipment may be to shut it down and disconnect it from the electrical supply when practical.
If you choose to unplug equipment, don't do so while standing in water or when there is another electrical safety hazard. Follow local safety guidance and use caution around electrical equipment.
Remember that a computer can potentially be connected to more than one pathway into your home. If you're concerned about severe weather and your equipment has network, cable, or telephone connections, consider those connections as part of your overall protection strategy.
Can you plug a UPS into a surge protector?
In general, connect a UPS directly to an appropriate wall outlet unless the UPS manufacturer specifically provides different instructions.
A UPS is already designed to manage incoming power and provide protected output for connected equipment. Adding another surge protector between the wall outlet and the UPS can interfere with how the devices are designed to operate.
Always follow the connection instructions provided by the UPS manufacturer.
Frequently asked questions
Is a power strip the same as a surge protector?
No. A basic power strip provides additional outlets but does not necessarily protect equipment from power surges. A surge protector contains circuitry specifically designed to limit or divert transient overvoltage.
Always check the product specifications rather than judging by appearance.
How many joules should a computer surge protector have?
There isn't one universal joule rating that's right for every computer.
The joule rating indicates the amount of surge energy the device can absorb, and higher ratings generally indicate greater energy-absorption capacity. Consider the value and sensitivity of your equipment along with the manufacturer's specifications when choosing a surge protector.
Do surge protectors wear out?
Yes. Surge protection components can degrade over time and after surge events.
Some products include an indicator that shows whether protection is still available. Follow the manufacturer's replacement recommendations and replace a surge protector if it has been damaged or indicates that protection is no longer functioning.
Does a surge protector protect against a power outage?
Not necessarily.
A surge protector is designed primarily to address voltage surges. It does not provide battery power during an outage.
If you need temporary power during an outage, consider a UPS.
Is a UPS better than a surge protector?
They serve different purposes.
A surge protector helps protect equipment from transient voltage surges. A UPS can provide surge protection along with temporary battery power during an outage, depending on the model.
For a desktop computer where uninterrupted power matters, a UPS may provide benefits beyond those of a basic surge protector.
Can I plug a surge protector into another surge protector?
It's best to avoid connecting surge protectors or power strips in a chain. Follow the manufacturer's instructions and connect your equipment using an appropriate device with enough capacity for the total load.
Can a surge protector prevent all computer damage?
No. Surge protection reduces risk, but no device can guarantee protection against every electrical event.
A comprehensive approach combines surge protection with safe electrical practices, backups, and appropriate protection for connected equipment.
Should I use a surge protector with my laptop?
A laptop's battery provides some protection from a brief loss of AC power because the computer can continue running from its battery. However, its AC adapter is still connected to the electrical supply when charging.
A properly rated surge protector can provide an additional layer of protection for the charger and other connected equipment.
A simple computer power protection setup
For many home users, a practical setup could look like this:
Laptop:
Use a properly rated surge protector when charging at home. Keep important files backed up.
Desktop PC:
Connect the computer and monitor to an appropriately rated surge protector or UPS.
Home office:
Consider protecting the computer, monitor, router, printer, and other essential electronics while staying within the protection device's electrical capacity.
Critical equipment:
Consider a UPS for equipment where unexpected power loss could cause data loss or an unsafe shutdown.
Whole home:
If you're concerned about broader electrical surge protection, talk with a qualified electrician about whole-home surge protection.
Protect your computer from more than cyber threats
Computer security isn't limited to malware, phishing, and other online threats. The physical environment around your technology matters too.
A properly selected surge protector can help reduce the risk of damage from transient voltage events. A UPS can provide additional protection and battery backup when power reliability matters. Regular backups can help protect your information even when hardware protection isn't enough.
Together, these precautions create a more complete approach to protecting your computer, your equipment, and the data you depend on.
