# Uninterruptible Power Supply- Do I really need one? **URL:** \ **Category:** Factual Questions\ **Created:** [March 12, 2009, 4:31pm UTC](https://boards.straightdope.com/t/uninterruptible-power-supply-do-i-really-need-one/489216 "2009-03-12T16:31:49Z")\ **Posts on this page:** 10\ **Page:** 2
**Author:** ![Richard\_Pearse](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/richard_pearse/32/13144_2.png) [@Richard\_Pearse](https://boards.straightdope.com/u/Richard_Pearse)\ **Post date:** [March 14, 2009, 5:50pm UTC](https://boards.straightdope.com/t/uninterruptible-power-supply-do-i-really-need-one/489216/21 "2009-03-14T17:50:33Z")
> [@GusNSpot](#): > > IMO, operating your electronic equipment during a thunder storm with frequent lightning strikes indicates a lack of good sense and so I just hope those that do continue to be lucky. Yes. The beauty of having a laptop is that you can unplug it and still use it, even better if you have an internet connection through your cell phone. ---
**Author:** ![Really\_Not\_All\_That\_Bright](https://avatars.discourse-cdn.com/v4/letter/r/e8c25b/32.png) [@Really\_Not\_All\_That\_Bright](https://boards.straightdope.com/u/Really_Not_All_That_Bright)\ **Post date:** [March 14, 2009, 8:14pm UTC](https://boards.straightdope.com/t/uninterruptible-power-supply-do-i-really-need-one/489216/22 "2009-03-14T20:14:34Z")
I had a motherboard fried during a thunderstorm despite surge protectors built into the apartment building’s electrical system and a home one between the wall and the system. It was weird- power supply was fine, motherboard power socket was cooked. Big black sooty spot, like in a cartoon. As far as UPSs go, we have them on every system in the office and they seem to be more or less completely useless. They’re all APCs, and about 90% of the time they don’t kick in fast enough, so our systems shut off and reboot anyway. ---
**Author:** ![Snnipe\_70E](https://avatars.discourse-cdn.com/v4/letter/s/b5a626/32.png) [@Snnipe\_70E](https://boards.straightdope.com/u/Snnipe_70E)\ **Post date:** [March 15, 2009, 1:57am UTC](https://boards.straightdope.com/t/uninterruptible-power-supply-do-i-really-need-one/489216/23 "2009-03-15T01:57:48Z")
> [@Really\_Not\_All\_That\_Bright](#): > > I had a motherboard fried during a thunderstorm despite surge protectors built into the apartment building’s electrical system and a home one between the wall and the system. > > It was weird- power supply was fine, motherboard power socket was cooked. Big black sooty spot, like in a cartoon. > > As far as UPSs go, we have them on every system in the office and they seem to be more or less completely useless. They’re all APCs, and about 90% of the time they don’t kick in fast enough, so our systems shut off and reboot anyway. You have something wrong there. They do not kick in. They should be floating on line. ---
**Author:** ![Q.E.D](https://avatars.discourse-cdn.com/v4/letter/q/51bf81/32.png) [@Q.E.D](https://boards.straightdope.com/u/Q.E.D)\ **Post date:** [March 15, 2009, 2:07am UTC](https://boards.straightdope.com/t/uninterruptible-power-supply-do-i-really-need-one/489216/24 "2009-03-15T02:07:17Z")
> [@Snnipe\_70E](#): > > You have something wrong there. They do not kick in. They should be floating on line. Actually most cheap UPS units, such as APC, are offline or standby mode types. They switch over to mains supply when parameters such as the voltage and line noise are within tolerance and switch over to the internal battery/inverter when it isn’t. ---
**Author:** ![Fantome](https://avatars.discourse-cdn.com/v4/letter/f/e9c0ed/32.png) [@Fantome](https://boards.straightdope.com/u/Fantome)\ **Post date:** [March 15, 2009, 2:20am UTC](https://boards.straightdope.com/t/uninterruptible-power-supply-do-i-really-need-one/489216/25 "2009-03-15T02:20:57Z")
> [@Q.E.D](#): > > Actually most cheap UPS units, such as APC, are offline or standby mode types. They switch over to mains supply when parameters such as the voltage and line noise are within tolerance and switch over to the internal battery/inverter when it isn’t. Does this mean that you’re not getting any extra protection that a surge protector would give you, assuming there’s never a power outage, such as making up for voltage sags or tiny spikes a surge protector would have caught? Or does the UPS kick in quick enough to compensate for voltage sags, which supposedly are harmful to PC parts? ---
**Author:** ![Q.E.D](https://avatars.discourse-cdn.com/v4/letter/q/51bf81/32.png) [@Q.E.D](https://boards.straightdope.com/u/Q.E.D)\ **Post date:** [March 15, 2009, 2:26am UTC](https://boards.straightdope.com/t/uninterruptible-power-supply-do-i-really-need-one/489216/26 "2009-03-15T02:26:48Z")
A UPS will kick in within 4-25 ms following an out-of-spec line condition (voltage too high, too low or too noisy), which is fast enough that most equipment won’t notice it. In addition, they almost always incorporate some sort of suppression, usually in the form of MOVs, so combine the protection of a surge suppressor strip with the ability to handle dropouts and brownouts. Note, BTW, that outlets trips do NOT compensate for voltage dips or sags; if you’re plugged into one thinking it will, you’re mistaken. ---
**Author:** ![Fantome](https://avatars.discourse-cdn.com/v4/letter/f/e9c0ed/32.png) [@Fantome](https://boards.straightdope.com/u/Fantome)\ **Post date:** [March 15, 2009, 2:33am UTC](https://boards.straightdope.com/t/uninterruptible-power-supply-do-i-really-need-one/489216/27 "2009-03-15T02:33:28Z")
Okay, so is it worth it to have an average priced APC UPS to protect a $550 dollar PC and a $200 monitor, or will all the parts most likely last just as long with a surge protector? And if a surge protector is enough, will a cheapo $8 surge protector do, or is there something specific in buying one I should look for that a cheap model won’t have? ---
**Author:** ![Q.E.D](https://avatars.discourse-cdn.com/v4/letter/q/51bf81/32.png) [@Q.E.D](https://boards.straightdope.com/u/Q.E.D)\ **Post date:** [March 15, 2009, 2:41am UTC](https://boards.straightdope.com/t/uninterruptible-power-supply-do-i-really-need-one/489216/28 "2009-03-15T02:41:12Z")
Considering an average-priced APC UPS runs in the range of $70-80, I think it’s worth it, but that’s at least partly because there are fairly frequent power dips and outages in this area, due to older electrical distribution infrastructure and I find losing work to be annoying. If it’s purely equipment protection you’re primarily interested in, then a good-quality surge suppressor ($40+) is sufficient as the vast majority of electrical damage is due to voltage spikes and surges. Note that even then, there are no guarantees. Recently, something bad–I don’t know what–happened either within my own equipment or on the line which caused the UPS to display a “Relay Weld” alarm and also took out the ethernet and SATA controllers on my motherboard. In addition to a 500 kVA APC ups, I also have a midrange Tripp-Lite Surge suppressor which is interposed between the UPS and the computer. ---
**Author:** ![GusNSpot](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/gusnspot/32/436_2.png) [@GusNSpot](https://boards.straightdope.com/u/GusNSpot)\ **Post date:** [March 15, 2009, 3:38am UTC](https://boards.straightdope.com/t/uninterruptible-power-supply-do-i-really-need-one/489216/29 "2009-03-15T03:38:58Z")
> [@Really\_Not\_All\_That\_Bright](#): > > I had a motherboard fried during a thunderstorm despite surge protectors built into the apartment building’s electrical system and a home one between the wall and the system. > > It was weird- power supply was fine, motherboard power socket was cooked. Big black sooty spot, like in a cartoon. > > As far as UPSs go, we have them on every system in the office and they seem to be more or less completely useless. They’re all APCs, and about 90% of the time they don’t kick in fast enough, so our systems shut off and reboot anyway. That is weird. I have six UPS in the house, 4 different brands, and we lose power a lot. Never had them react slow enough to drop any of the equipment. Only one was bought new, all the rest are garage sale or junk store finds… I do go inside and kill the ‘beep beep’s’, they drive me nuts… One I have on my system is using 2 12V lawn tractor batteries… I can operate for a loooong time without the electric company. I have a separate one on my router/modem which will carry that for a loooong time so when the ice brings the lines down, if the phone stay, we are golden. But for true freedom / protection, you need to do it like **1920s Style “Death Ray”** does… ---
**Author:** ![Q.E.D](https://avatars.discourse-cdn.com/v4/letter/q/51bf81/32.png) [@Q.E.D](https://boards.straightdope.com/u/Q.E.D)\ **Post date:** [March 15, 2009, 3:45am UTC](https://boards.straightdope.com/t/uninterruptible-power-supply-do-i-really-need-one/489216/30 "2009-03-15T03:45:28Z")
[quote=“1920s Style “Death Ray”, post:9, topic:489216”] The circuit breaker on the surge protector would be “popped” if it had done its job for you, so you’d know about it because you’d have to reset it before you could use it again. [/QUOTE] I missed this before. This is not correct. The resettable circuit breaker is only for overcurrent protection; for the typical outlet strip, it will trip if a load exceeds 15 amps, but this takes several seconds at typical overloads. The surge protection is provided by solid-state MOVs, which work by shunting excess voltage around the load and/or to ground. This _may_ trip the breaker if the surge current is sufficiently high, but in most cases it will not. [Previous page](https://boards.straightdope.com/t/uninterruptible-power-supply-do-i-really-need-one/489216.md?page=1)