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Is a UPS Better Than a Surge Protector?

Uninterruptible power supply for a computer

Whenever you buy a new computer or most other expensive electronic devices, chances are that the salesperson is going to encourage you to purchase a surge protector, as well.

Aside from being high-profit add-in items, quality surge protectors actually do serve an important purpose. As their name implies, they help protect your expensive electronic equipment from harmful electrical surges and spikes.

When the device being protected is a computer, however, surge protectors do not provide adequate protection. With the exception of laptops and other devices with working internal batteries, computing devices need an uninterruptible power supply, or UPS for short, to protect their power supply. A surge protector is not enough protection for a computer.

Let me explain it to you.


How is a UPS Different from a Surge Protector?

Backblaze online backup graphic

Both surge protectors (or "surge suppressors") and UPS's protect their connected devices from power surges and spikes. The difference is that UPS's also contain batteries that provide power to the connected devices for a short time if the utility power goes down. How long a time depends on the capacity of the UPS and the total current draw of the connected devices.

The best UPS's provide a pure sine wave output, which most closely replicates the power provided by the utility company. If your computer has an Active PFC power supply (which most newer computers do), then you must use a pure sine wave UPS. A UPS that produces a PWM or "modified" sine wave will provide no outage protection whatsoever for your computer, and may actually damage the computer.

If the connected device doesn't have an Active PFC power supply, then usually you can use either type of UPS.


Why do Computers Need Uninterrupted Power?

Your computer needs an uninterrupted source of power for three reasons:

  1. To give you time to save your work if a power outage occurs while you're working on a project. Without a UPS, any work that hasn't been saved will disappear if the power goes down.
  2. If you're using your computer to chat with other people, download large files, pay bills, purchase something on the Web, and so forth, a UPS will give you time to either finish those activities or pause them in an orderly way. For example, if you're on a video call, you can inform the person you're talking to that the power has gone down so they don't think you disappeared or hung up on them.
  3. Losing power during certain operations such as installing software or installing system updates can leave your computer in an unusable state, sometimes to the point of being unable to even boot up. Having an uninterruptible source of power is the only way to avoid this risk.

The only computers that don't need uninterruptible power supplies are laptops and other portable computing devices that have working batteries and are adequately charged. These devices effectively provide their own battery backups.

Other electronic devices such as phones, cable television boxes, and streaming boxes usually don't need uninterrupted power unless you want to be able to use those devices during a power failure. If not, then a surge protector is a perfectly-good and much less-expensive power-protection solution.