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Will a UPS physically "protect" computing hardware?

  1. Oct 16, 2016 #1
    I did as much research into UPS units as I thought I needed in order to understand all of the top level jargon, but the fundamental issue of whether the appliances plugged in will be physically protected hangs over the entire industry (for domestic use).

    For example, a CyberPower UPS unit claims that it employs "Surge Protection & Filtering" with a surge "suppression" of 405 Joules. However, lighting will strike power lines with many hundreds of thousands of Joules, so how can such a UPS be of any genuine use?

    ref: https://www.cyberpower.com/uk/en/product/sku/CP1500EPFCLCD

    My reckoning was that the lightning strike would be sufficiently suppressed at the power station level before it reached my home's power lines, but I just don't know, there are many variables. Just how realistic can domestic computing hardware be protected when plugged into utility supply? (through a UPS)

    Another thing: there is apparently no such thing as a perfect sinusoidal wave, both "clean" and "dirty" power suffer from spikes; noise, and ripple voltages, but with the way DC powered microelectronic devices are designed today they do not suffer from these fluctuations as UPS manufacturers would have us believe, such claims are then a gimmick?

    The one thing I need are solid numbers, not claims, but the actual irrefutable numbers. I am not smart enough to do that, I need help from people that are, to put this issue to rest.

  2. jcsd
  3. Oct 16, 2016 #2


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    Are you worried about lightning strike surges or about power outages? Those are very different issues.
    Laptop computers already have a battery to keep them from being damaged by power outages, but it is a serious threat to desktop and tower computer hard drives.
    Power surges from lightning strikes can be huge. The best protection on the power line is a whole house surge protector. There may be other ways that a lightning surge can get to your computer.
  4. Oct 16, 2016 #3
    The two tiered approach is definitely the way to go. :thumbup:
  5. Oct 19, 2016 #4
    Thank you for you're replies.

    I suppose I should structure my questions better. But, as we're on the subject of lightning and power outages then let's begin:

    ** all instances my assume that a desktop PC will be in the equation **

    Lightning, this can send hundreds of thousands to millions of Joules in a single bolt. Naturally this would overwhelm any domestic (sub £500/$600) UPS of which is typically rated to "absorb" only around 400 Joules at that price point for example. I don't even know if the UPS will protect connected hardware from anything less than the rated number of Joules either, is it just marketing speak, what actually happens to those Joules?

    Clearly, lightning is too much for a UPS, in such an event I assume the hardware would be fried, or at least damaged, with a direct power line hit? In which case, disconnecting it from the wall until the storm passes would be the best option, either running from the batteries in the UPS or gracefully shutting down.

    Aside from the physical connection that my desktop computer has to the outside world drawing power from the utility wall outlet, it also has a physical connection to two external HDDs, attached via USB ports, these themselves are utility powered and so they would need to be protected also. Another would be a pair of wireless headphones, of which the base station is powered from the wall utility outlet and once again connected to my desktop PC via usb port, those too being a route for the electricity to wreak havoc.

    So, what would a UPS protect my hard from, not lightning that's for sure! But, what of the sub 400 Joules mark, would is actually be able to stop that, or not?

    As you mention, laptops would operate reliably when the power drops completely, this is what got me thinking about a UPS when I switched from regular laptop usage to a desktop in the first place (the safety stuff came later). As I'm running both a desktop and external HDDs (all powered from utility wall outlet power) I see a battery backup as a clear benefit, I don't think that can be denied. However, some may dispute a sudden shut down is an issue for a HDD, but I think it would be, however unsure about SSD (I can look into that) and what of desktop PCs, how do they become damaged from a sudden loss of power - does it really matter?

    Software wise, I don't need to prove that one, just the hardware side of things.

    Thanks again!
  6. Oct 19, 2016 #5
  7. Oct 19, 2016 #6


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    I assume that the danger from lightning strike surges covers a wide range depending on what and where the lightning strikes. (After all, a direct hit will burn the whole house down.) Also a fault in your electric provider's equipment can cause a voltage surge that lasts a long time and will exceed most surge protection. A whole house surge protector can provide a lot more protection. The SquareD HEPD80 is rated at 3,300 Joules according to their specs.

    When I switched from laptop to tower, I never could get more specific advice than to get a UPS. I tend to shut the computer down when I am not there or when thunder storms are near so that the hard drive would not be active in mid-write when power goes out. But I still wanted one because my house has so many unexpected power interruptions. A UPS gives me time to shut down programs and I have done it a few times in the last year.
    Last edited: Oct 19, 2016
  8. Oct 19, 2016 #7


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    again, you are still mis-understanding the primary use for a UPS

    Primary use ... supply power for a limited time ( depending on load, maybe ~30 minutes .... time to do saves of data, close programs, and shut down) in the event of a power cut

    secondary and LIMITED use .... will provide some surge protection. Totally dependant on its ratings and the energy of the surge

    I definitely wouldn't rely on it for that feature and would ensure other protection be installed at the power entry point of your home
    and even then, NOTHING will stop a close by direct strike on power lines or phone lines

  9. Oct 20, 2016 #8
    UPS units mainly provide protection from voltage and frequency levels out of range. They do provide some surge protection, but not enough really. Typically they only provide about 500 Joules of protection. Lightning strikes can generate much more than that. I had a whole house surge suppressor in the last home I owned. That was the best solution. The one I installed at my breaker panel was good for 5kJ. At this time I'm renting rather than owning so installing a whole house surge suppressor is not really an option. What I've done is added a Tripp-Lite Isobar suppressor in front of each UPS unit. The Isobar suppressors are good for 3.3kJ.

    There's not really anything the power company does to protect your home from a local lightning strike. In the area I live we get some pretty heavy lightning storms so surge suppression is a must. There's other sources that can come from power company equipment. They generally do a good job of filtering power, but if a transformer blows or some other equipment fails they can't always ensure that won't create a surge.

    I also put surge suppressors on my cable TV lines which supply all my home services. I use a simple inline one Leviton makes that's pretty good, only 0.3dB insertion loss. Surges over the cable lines are pretty rate but they can happen from solar storms. It may not be necessary to protect them, but a surge over cable TV lines can do a good amount of damage as well.
  10. Oct 20, 2016 #9


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    Yeah. What he said.
  11. Oct 21, 2016 #10
    Yes nothing can protect from a direct strike, but that should be pretty rare. I mean if your house gets hit by lighting, you'll have much more damage to deal with than appliances connected to the mains supply. That will be a big insurance claim. Most commonly strikes are close by that won't do any more damage than create a large surge over electrical lines. I've been hit with a good number of those in the past. In fact I might even need to replace my surge suppressors by now. The ones I have provide a health indicator and they're still reporting good protection, but just to be sure it would probably be a good idea to replace them. The components they use in them wear out pretty quick after they've dumped a lot of energy a number of times.
  12. Oct 21, 2016 #11


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    doesn't necessarily mean a direct house strike ..... any power line strike within a couple of km or so of the house is going to produce transients that will fry a lot of the electrical / electronics in the house. Surge protectors will have little to zero effectiveness. I have seen the results of that many times in my former job

  13. Oct 22, 2016 #12
    Yeah that's like millions of Volts right in the kisser, so yeah nothing can survive that. I think those are still fairly rare. I've yet to get hit with one like that and we get some pretty energetic lighting storms where I live.
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