Usually nothing bad, but sometimes…
Shutting down Windows properly before turning off the power to your computer is important.
Not doing so can result in data loss and corruption as files are left only partially written to disk, but turning off the switch is unlikely to harm your hardware.
Surprisingly, a household or other area-wide power outage presents a different, riskier issue.
Power loss
Turning off your computer without shutting down can corrupt files, but it rarely damages hardware. But the surges, brownouts, and intermittent power involved in a power outage can hurt your equipment. A surge protector helps, and if your area loses power often, an Uninterruptible Power Supply, or UPS, is even better.
Shutdown
Windows often keeps things in RAM memory that need to be written to disk, and shutting Windows down properly gives it the opportunity to flush all that information to the hard drive. If you happen to turn off the power while Windows is writing something to the disk, you run the risk of corrupting files. In the simplest case, which thankfully seems to be the most common, you never notice. In the worst case, your system might become unbootable.
But actual hardware damage from turning off the power switch at the wrong time is rare. More common are data-related errors, which, as you say, can be resolved in the absolute worst case with a reformat and reinstall.
Help keep it going by becoming a Patron.
Power loss
So why is household power loss different?
Many times it’s not; the power just goes out as if someone threw a switch. That’s pretty close to turning off the power as we discussed above.
Unfortunately, many times it’s not that clean.
A great example is the windstorms we suffer in the Seattle area. As trees fall onto power lines, various things happen.
- Power “blinks” while the power grid automatically re-routes through other circuits, compensating for a supply line that has just been cut.
- Power “browns out” as power lines begin to short or fall onto trees and other structures, where they make a partial connection. Brown-outs occur when the voltage on the line falls to levels lower than the normal 120 volts used in the U.S.
- Power “surges” as power lines short with each other or fall onto other electrical equipment. A surge pushes the voltage above the normal 120 volts. Automated equipment is supposed to cut power when this happens, but the leading edge of the surge almost always makes it out to customers in some form.
- After any of the above, power may finally go out. It may go out suddenly, it may brown out and go away, or it may go away in a sudden surge.
Even areas with primarily underground power distribution are still at risk, since the high-voltage feeds that bring power are still typically above ground. And, of course, situations besides windstorms can cause power failures with all the symptoms I’ve described above.
Losing power due to a power outage is typically not nearly as clean as just turning off a switch. And that “messiness” has the potential to damage connected electrical devices.
Power loss protection
Consider your poor computer (or any electronic device) connected to power that’s browning out, surging, blinking, and more before it finally goes dark.
Some computers and equipment can handle that mess. Some computers and equipment cannot.
In fact, a lone power surge can damage sensitive or just plain cheap equipment.
So, what do you do?
I have two recommendations that depend on how frequently you experience power problems in your location.
- Surge protectors. Note that a power strip is not necessarily a surge protector. A power strip merely distributes power to multiple outlets, while a surge protector includes additional circuitry to automatically and cleanly cut power in the case of a power surge.
- Uninterruptible power supplies. UPSs are batteries with circuitry that continue to provide backup power if the primary power source fails. As a side effect, they typically include power “conditioning”, which can eliminate temporary drops, surges, and brownouts. If the incoming power becomes too unstable, they switch to battery backup.
What you need depends on your situation.
My UPSs
As of the last update to this article, I have three APC UPS Back-UPS Pro 1500VA UPSs, each in a different location in my home. They’ve served me well through assorted power issues in recent years.
There’s no reason not to use a surge protector. They’re inexpensive insurance. Many of what we would think of as plain power strips are surge protectors as well. All of your desktops, most printers, and other equipment should be connected to power through a surge protector.
If you experience frequent power problems or if your computer is particularly sensitive or critical, then getting a UPS and connecting through it makes a lot of sense.
Laptops typically don’t need any special treatment. In a sense, a laptop has its own UPS built in, since even when plugged in, it’s running from the battery (which is getting charged back up at the same time). Connecting through a surge protector doesn’t hurt. Connecting a laptop through a UPS is somewhat redundant, however, and would even add an unnecessary drain on the UPS’s battery if the power went out.
My desktop computers are connected to UPSs, as is some of my networking equipment. My laptops, of course, will run on their internal batteries in case of a power failure. All together, this allows me to stay online for a while before the battery runs out, as well as perform a clean shutdown if I choose to.
Do this
Use a surge protector for your desktop computers, printers, and the like. If your area is prone to occasional power problems, consider a UPS for your computer.
Subscribe to Confident Computing! Less frustration and more confidence, solutions, answers, and tips in your inbox every week.
While living in Florida a few years ago, I made friends with a fellow who worked as a manager at the local power company. He told me that many computer users have a surge protector, but aren’t aware of the danger brown-outs can cause their electronics – including computers, TVs, and other expensive gear. It seems that most of the interfaces in modern electronics (the power supply) will attempt to keep the flow of electricity to the rest of the device at a steady state. If the incoming voltage begins to drop, the power supply will try to adapt; if the incoming power gets to brown-out conditions, the power supply may work so hard that it destroys itself in the process of trying to keep the proper power flowing within the device. Even a $50 Uninterruptible Power Supply (UPS) will stop brown-out damage.
Fortunately, here in the UK, we don`t get too much in the way of serious power cuts, but I`m located rurally and if there`s a storm, the power does sometimes take a dive. Being an ex-telephone engineer, I`m fairly aware of the problems that can arise, especially in the situation where low volts is worse than no volts at all. This happened in the last cut we had for 16 hours and we had about 50 – odd volts coming through (normal UK is 240)and various pieces of my electronics gear over and above my PC`s, (hi-fi amp, etc) were initially trying to run, cutting in and out and doing odd things! I`d already turned everything off before being advised to do so by the electricity supplier when I reported the problem. This is slightly off-topic, but, as I understand it, motor-driven appliances (fridges/freezers, etc.) can sit there trying to run in a low-volts situation and can actually cook up if they are not running properly, as some motors/compressors have built-in fans to keep them cool. If these aren`t running properly you could end up forking out for a new one! Don`t do what I did (I feel silly here) and forget to turn said freezer back on after power is restored! No further comment!
You said that connecting a laptop to a UPS is pointless but since we’re told NOT to leave the battery in while connected to an electrical outlet then if there is a power failure wouldn’t the machine still be vulnerable to all the nasty things that can happen from not being shut down properly? If a UPS is not the way to go then what is? My laptop (and printer, scanner etc) is currently connected to a good surge protector. When the voltage fluctuates I hear a “clicking” sound and see the “boost” or “trim” light go on.
Not to leave the batter in while connected to an electrical outlet? How else would you recharge the battery then? The battery on your laptop will act exactly the same as a UPS…. If the power goes out, your battery will take over.. Notice you can freely attach and detach the power from your laptop without worrying or losing any kind of current form the computer… You can do the same with a UPS..
—–BEGIN PGP SIGNED MESSAGE—–
Hash: SHA1
I know that there are many who recommend removing the battery from your laptop
if you’re going to leave it plugged in for a long time. (After letting the
battery recharge, of course.) Supposedly it lengthens the life of the battery.
I don’t do that. For various reasons, the batteries are in all the time on all
four of the laptops here. The battery acts as a UPS, particularly when the
power cord gets tripped over, or you want to move the laptop from one location
to another. A quote from an earlier article of mine:
“A concern that I’ve had for a long time is whether or not leaving a laptop
plugged in for extended periods of time would harm the battery. Today’s designs
pretty much expect that type of usage, so it’s not the issue I was afraid it
might be.” – from http://ask-leo.com/how_do_i_maximize_my_battery_life.html
But yes, if you do remove your battery, then you’ll want to treat your laptop
as if it were a desktop, and plug it into a UPS.
Leo
—–BEGIN PGP SIGNATURE—–
Version: GnuPG v1.4.7 (MingW32)
iD8DBQFG7qZrCMEe9B/8oqERAjKRAJ9wsL/FsW9aF3alfN0CFZ89ahyy5QCgi7FD
pI6sjEcPenqxLn9PtvmIrfs=
=qc9C
—–END PGP SIGNATURE—–
Re: ‘..while a surge protector includes additional circuitry to automatically and cleanly turn off power in the case of a power surge.
Granted, not all power strip appearing devices (multiple outlets) are surge protectors. Of the units that ARE surge protectors, many of them are useless! Why? Because after whatever protection in them has been ‘used’ and therefore NO protection exists at all, they STILL PASS POWER TO THE OUTLETS. They do NOT, ‘..cleanly turn off power..’
You think you are protected when you are not.
A surge protector/expansion strip device that works as it should will NOT pass power once the suppression/protection part of it is ‘used’ (damaged due to spike suppression). The simple ‘damaged but still useable’ devices would likely consist simply of MOVs (Metallic Oxide Varistors), avalanche or zener diodes.
I think! 😉
hi, you said “In the worse case your system might become unbootable.”
well, this happened to my boyfriends computer. Basically, whenever the computer was turned on, it would freeze while booting up and none of the safety modes would work.
We fixed this problem by using a XP restore cd however when we finally go to the start up menu we realised that all his pictures/music/most of his programs had disappeared.
Yet, when we looked at the memory the computer was still taking up as much memory as it used to which we took to mean as the files are still on the computer.
Is there anyone out there who could help me on getting these files back?
Does anyone know of any programs that could do this for me?
We are not sure where the files could be, we’ve looked everywhere on the hard drive.
We’ve used some file recovery programs but because the files aren’t techniqually ‘deleted’ as such, those programs are virtually useless to us.
Please help !!!
Try Recuva.
Thanks for the feedback. I feel better now about leaving the battery in all the time and not just when it’s charging. Surges, brownouts and total power failure, while not regular, are not uncommon where I am. I use my laptop many hours everyday so it’s good to know I have the option to let my battery function like a UPS.
One more question. How do you know if your surge protector is actually working? According to the post by Brad L we may think they’re working when they’re not. I use a Tripp Lite voltage regulator and conditioner and would really like to know for sure that it’s working. Is there a way to find out? It shows a steady green light most of the time but occasionally the boost or trim light would go on accompanied by a “ticking” noise. Any feedback would be appreciated.
A modestly priced UPS is a good investment to protect your costly computer equipment from power drops, brownouts, spikes, and surges. I have one each for both desktops, my SAT receiver-DVD, and a pair of modems for internet and a VOIP phone system. Those on the computers have an endurance of just several minutes and so are arranged to send them a shutdown signal (easy to set up). Peace of mind for our tech-dependent era.
Regarding the laptop battery, by all means keep it in. But do use battery management software (standard on some higher quality gear) to extend battery life. Lithium-ion batteries have longest life at approximately 50% charge so, unless I expect to use it on battery for more than 2-3 hours, I have the laptop set to stop charging at 55%. And if you ever have to replace your laptop’s battery get the OEM part for safety reasons (more likely to be a quality part and matched to the charger’s characteristics).
Instead of purchasing multiple surge protectors for all your electronics, this includes newer major appliances, TV’s, toaster ovens etc, it is, at least I think, more advantageous to install a ‘whole house surge protector’. These install on the electrical panel and are well worth the cost. One example is found here: https://www.homedepot.com/p/Siemens-FirstSurge-Pro-140kA-Whole-House-Surge-Protection-Device-FS140/206560230
We had whole house surge protection put on when our power box had to be shifted and larger mains input installed for our whole house air conditioning system about 20 years ago. Everything worked OK until about 10 years ago when a truck with a crane on it managed to go through the three main phases down the street from us and wrap them together. Our mains power box literally was destroyed and we then had no power – this was Easter Friday. Luckily my wifes cousin had his own electrical business and was able to come out and restore our power. Nobody else in street was affected and he said that was because they had no surge protection and ours copped the full blast of the massive surge. I live in Brisbane, Qld Australia and we get power outages due to storms, cyclones and strong winds. We also had one yesterday, we think caused by the electrical people working on the new house build next door. My laptop kept working but everything else went off for the few minutes. I leave my laptop battery in while my laptop is plugged into mains. I do occasionally remove power from laptop to make it run the battery down as I have been told this is good for the battery’s performance and lon
ger life time.
I used to use UPSes with a few 120Ah batteries. So when the power got down (regularly), we still had electricity for eight hours.
Is there anyone out there who investigates instances of paranormal computer activity? Of all the crazy things I have saw PC’s do over the years, last night my computer done something that nearly has me questioning my sanity. Here is what happened.
I never turn my computer off at night and it often will be running consistently for a week or two at a time until I reset it, due to instability or a software upgrade that requires a restart. Or if the power goes off; this obviously causes as reset. This computer does not have an Uninterruptible power supply (battery backup) even though I know I probably should. So a power outage ALWAYS results in a computer reset, or so I though. Last night at around 10 pm soon after I was in bed we experienced a whole house power outage that lasted approx. 3 minutes before power was restored. Everyone in the house agrees on the time, duration and the fact that it affected the entire house. There were multiple items in my room that lost power. This was not a “brown out” where the light go dim for a few seconds and then resumes. It was a complete black out.
When I got to my computer this morning I fully expected my computer to appear as it would have been after a fresh power start. By now you probably all know where this is going… Yes, to my surprise the programs that I had left open the night before when I left it about 9pm where all still running and the data files were still open! My password did not need to be entered as it normally would after a reboot. My computer had clearly remained running with no power. Just to be sure, I opened up the task manager which shows how long it has been running uninterrupted, and it showed 14 hrs. This put the time of the last restart at about 7pm last evening and I clearly remember having reset it at that time because of an instability issue.
The only theory I have at this point, and this is pretty far-fetched, is this: I had my wheelchair charging in an outlet on the same circuit breaker just a few outlets away. I normally don’t charge from here, but it was tonight. Possibly though some crazy electrical abnormality the wheelchair batteries acted as Uninterruptible power supply (battery backup). I don’t understand electricity enough to know whether this is a possibility, but I understand computers well enough to know that they cannot remain running without electricity.
Anyone have any other theory?
I have seen Windows restore applications that were open at the time of an unexpected shutdown.
I too have seen Windows restore apps/programs that were running when it was unexpectedly shut down. I have had a prompt on occasion when a desktop has come back up. I use a laptop for daily use but have a desktop in my workshop but am considering using a laptop there as well for power outage usage.
Power coming in to your house is normally three phase. You can lose one or two and anything connected to the remaining phase still works. Perhaps that’s what happened.
Windows 10/11 has a built‑in session restore mechanism, but it only works if the app supports it.
It’s the app itself that saves the session.
A slightly tangential question: if my PC hangs completely, as it sometimes does, and the old fashioned solution of “Control/Alt/Delete” does not work. What is the recommended action? In desperation I have resorted to pressing and holding the on-off button, waiting a few minutes, and rebooting. Is this the only method, or should I be doing something else less drastic to avoid damage to the machine?
That’s the only path I’m aware of.
Thanks Leo, glad to know I’m doing the right thing.
I’ve had that happen much more often than power failures. Here, power failures are a once every 5- or 6-year occurrences. I think the article should have included a paragraph or 2 on that as its functionally almost the same thing.
A few years ago we had a lightning strike a tree about 30 feet from the house. Judging by the trench it dug in the yard, the lightning followed a tree root to the point where underground power and cable enter the house. It fried the microwave, the clothes dryer and every light that was turned on. It also killed my desktop computer, the cable modem and router. Funnily enough, computer items were all on a UPS. The cable guy who came to replace the modem said the lightning arrester at the cable distribution box was fried as well. Here’s what I theorize: The lightning bypassed the UPS because everything was connected together by ethernet. It came in through the cable, fried the modem and followed the ethernet cable to the router and then to the computer. Now, while I still use the UPS I use WIFI to connect the desktop to the router even though it’s only a few feet away.
I have a surge protector that has not only electrical receptacles but also phone, coaxial cable (for the TV), and ethernet jacks. From what I understand, a surge protector can not deflect an excess electrical charge if the lightning strike is very close to the home. Remember too, many electrical things are grounded (that 3rd wire), but the electrical charge from that close by lightning strike COULD flow over that ground wire to everything that has a grounded connection. That excess electricity can also energize copper and cast iron water pipes.
A surge protector or a UPS that has Ethernet surge protection can help in some cases. It’s not perfect because a lightning strike can be too strong for it, but it’s worth trying. We have fiber optic Internet, so for lightning to affect us, it would have to hit at the junction box half a block from my house where the cables go to the house. Not 100% protected, but it increases the protection significantly.
In recent years, I’ve been hearing about whole home lightning protectors that can save all your home appliances, and since these are usually enterprise level protection, they may even keep such an event from doing any damage at all.
Ernie
Those would cost more than all of your electronic devices combined, but they might prevent your house from burning down. So, there’s that. 😉
Leo: Completely off topic. I see the AI app you use seems to be favoring corgi images in all your articles this week. They can be rascally little things at times. 😎
That’s not AI favoring corgi images. That’s Leo favoring corgi images. 😉
It may have had a little encouragement.
FWIW: ZFS and TrueNAS are unbelievably resilient to unplanned shutdowns.
I do have a 2kVA battery bank as a UPS for my home office. We’ve been through some awful phases of “load shedding” in South Africa due to power shortages and this can keep me going for over a day.
I was on my third Windows reinstall: because it wouldn’t start properly.
First one, I was told was because the kids had been visiting dodgy sites.
Second, maybe I didn’t do the first one properly (I did)
Third, I asked the kids to show me what they did when using it. “And Mum says turn off the computer, so we just turn it off at the wall”
Yup, that’ll do it. Showed them all how to shut down properly. Solved!
In terms of computers, I have a desktop and two laptop PCs. As Leo recommends, I do nothing for my laptops, other than keeping them plugged in. For the desktop and all it’s peripheral devices, I have a desktop surge protector that accommodates eight devices, so of course I have my desktop machine powered through the protector as well as my monitor, sound bar, Office TV, and a Roku device I use with my TV. The three remaining outlets serve power for charging my phone and any of my three tablets when required. Because I live in a metropolitan neighborhood near a shopping center, the electric power supply in my area seems to be very reliable … I encounter fewer than one outage each year, and even then, service is restored within a few hours. Kudos to my local Edison company!
Ernie
It’s good my laptop running on the battery is mostly safe.
My question is for my other equipment. The apartment I live in is old. All the outlets are two prong plugs without grounding. I have everything connected through power strips, I think with surge protection. Without grounding am I really doing any good?
I’m thinking not, but I could be wrong. Grounding has become an important part of our electrical system, and I would expect that things like surge protectors rely on it. (And even though my degree is in Electrical Engineering, this is very much outside of my wheelhouse — I spent my time on microprocessors and software. If others know with more certainty, chime in.)
We spent a full semester in college on Ohm’s Law and grounding never came up. I never would have imagined how complicated a 3 factor equation could get.
Trivia: the “opposite” of an ohm Ω is a mho ℧.