I know that all surge protectors/upc's need outlets that have earth ground and be three pronged to safely protect against lightnings, but I would like to know if they can help against power fluctuations, even if just a little.

I have started unplugging my computer during rain and thunder storms but sometimes in my house the power fluctuates before any storm begins which causes my computer to shutdown or restart unexpectedly. If a surge protector can help in these situation then it would be worth using to to me.

  • more expensive surge protectors usually condition the power as well. While it can't do a lot about brownouts, it will stop transients, noise, and can even fill in some of a missing sine wave (caused by a "short" somewhere else, like a motor kicking on). That additional conditioning could be enough to keep your computer happy. If not, you have a prolonged current drop, and you'll need a UPS.
    – dandavis
    Aug 3, 2018 at 19:39
  • First thing that I’d suggest doing is reporting that the power in your house fluctuates like this to the power company. It sounds like they have a loose and burning connector somewhere that is less stable with wind motion.
    – Tyson
    Aug 3, 2018 at 20:18

2 Answers 2


First, I'd suggest looking at Is is safe to plug a surge protector into a 2-prong outlet using a 3-to-2-prong adapter?. That may answer your question. I'd also suggest looking at the outlet box and seeing if it's already grounded, in which case you could just replace the outlet.

However, if it's protection against power fluctuations you want, I'd suggest a UPS, not a surge protector. They have an internal battery, and if you buy an Online/double-conversion UPS, the battery is always what's providing the power. They may well not like being without a ground.

  • +1 for the key part: "Online/double-conversion UPS".
    – dandavis
    Aug 3, 2018 at 19:37

Surge protectors are metal oxide varistors one is tied from hot to ground and another is connected from common to ground. They break down at specific voltages and dump the spikes to ground. To answer your question will they work with a 2 prong outlet NO there is no place for the spike to go. As Kevin said a ups would be the best way to go because of the isolation from the line voltage. Incoming line voltage is transformed. To the battery voltage and uses electronics to transform the dc back to AC when the power goes out the system keeps providing power using the battery until the battery is low on charge. The transformer is the key because this isolates the line voltage from the main the electronics create a new output, more expensive units create a pure sine wave less expensive create a sine wave that looks like small steps in the sine wave computers sometimes have trouble with the modified sine but many have become close to pure since and work well with computers and other digital equipment. Nothing other than unplugging will prevent damage of a direct. Or close lighting strike but these are rare. So to protect your computer 100% unplug. Close to 100% get a UPS. Because without a ground filters and MOV's won't work.

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