6 ms·

I would never buy a cheap UPS. The one time I did so many years ago, it ended up catching fire. UPS fires are the most common cause of datacenter fires, and t

I would never buy a cheap UPS. The one time I did so many years ago, it ended up catching fire. UPS fires are the most common cause of datacenter fires, and that's the "good" stuff. Adding a UPS is not a zero-risk action that has only upsides. You need to actually think about it. At home, I have had a single rack w/ network and server gear for more than a decade and I always run two good quality UPS, that I run a test on annually, tied to two different circuits. My setup now is a bit annoying because I'm renting currently, but when I owned a home prior to my recent move I had an electrician run two 20A Dual Function (AFCI+GFCI) circuits with hospital grade outlets to power the two UPSes in the same room but on separate circuits and breakers at the panel. I don't think that's overkill, but I think anything more would be overkill at home. When I buy a house again, I intend to do the same. Since buying better quality UPS and testing them regularly so I can replace batteries when needed I haven't had any fires, but using batteries past their useful lifespan can greatly increase risk of fire. Expect that you should replace the batteries every 3-5 years, and that they will cost nearly as much as the UPS itself. If you're not comfortable with that, invest in a quality surge protector instead and figure out how to deal with failures. UPS batteries are a big fire risk, so you need to understand it and work to contain it. Also, keep a good dry fire extinguisher near your rackmount equipment and get it tested annually.

turtlebits 3y ago
Can't you buy a UPS with a LiFePO battery, or find an old lead acid one and do a battery swap?
- cptskippy 3y ago
  UPSes with dead lead acid batteries are a dime a dozen. People don't realize or don't both servicing the batteries and toss them out all the time.
  - russdill 3y ago
    I love hooking up large lead acid batteries to old UPSes, there's no reason to be limited by the original battery capacity. However...I discovered why some APC UPSes are sealed and the battery cannot be accessed. I was converting one such UPS which had no monitor interface. Having already opened it up to splice in an external battery, I noticed an empty header for a serial port. Cool. Plugged that into my PC and flash/bang/smoke. Fortunately my PC had a good path to ground and was not damaged. But the UPS had some pretty large burn marks at various points in the PCB and was certainly dead. It took me a bit to figure out what I did wrong. The reason it went bang is directly related to why there's no user access to the battery, and why there's no external monitoring port. They went cheap on the electronics and did not include an isolation transformer. Any points within the UPS which are "ground", including the battery negative terminal, are actually referenced to the full bridge rectifier, which provides a direct path to live. Ahh...I'm just very glad I didn't touch any of the battery terminals while I had the thing plugged in.
bongodongobob 3y ago
Nonsense. UPS's don't pose any sort of serious fire risk. UPSs starting on fire are exceedingly rare. Sure, it's probably happened. People get hit by lightning too.
- silon42 3y ago
  I'd guess they are certainly safer than a laptop, but it depends on a manufacturer... (I've seen lots of "balooned" laptops, including many Macs)
- tristor 3y ago
  Not to be snarky, but UPS fires are one of the leading causes of datacenter fires: https://duckduckgo.com/?hps=1&q=UPS+Fire+datacenter&ia=web https://duckduckgo.com/?hps=1&q=UPS+Fire+datacenter&ia=web
  - bongodongobob 3y ago
    Right and data center fires are extremely rare. Think of how many UPSs are in the wild. The failure by fire rate is probably something like 0.000001%.
deleted 3y ago
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Grazester 3y ago
After using hundreds, hundreds of very cheap to huge expensive APC UPS' I can say I have never experienced a fire. They have all used lead acid batteries, some as heavy as 50lbs. I have even had to cut UPS' open to remove swollen batteries.
dheera 3y ago
Is this specific to Lithium battery UPS units? For home use I bought a lead acid UPS specifically to avoid a fire. For a 5 hour power outage it makes no difference to me if the UPS powers my machine for 5 minutes or 20 minutes; as long as I can save my stuff and shut down it works for me.
wannacboatmovie 3y ago
> I had an electrician run two 20A Dual Function (AFCI+GFCI) circuits Don't do this. This is a terrible idea if you intend to run a UPS. > with hospital grade outlets Complete overkill and waste of money > UPS batteries are a big fire risk No they aren't. Judging by all these incorrect assumptions about electrical, I'd suggest stopping while you're ahead before you burn your own house down.
- bloopernova 3y ago
  > > I had an electrician run two 20A Dual Function (AFCI+GFCI) circuits > Don't do this. This is a terrible idea if you intend to run a UPS. Can you please elaborate why someone shouldn't do that? (not who you responded to, I'm just curious about the reasoning behind that statement)
  - wannacboatmovie 3y ago
    UPS's are notorious for nuisance tripping GFCI's due to the extensive power filtering they usually have inside. It may not happen right away but is dependent on how 'dirty' your power is and on how sensitive your particular brand of GFCI is. All it may take is a neighbour using his AC or power saw and it could generate a spike large enough to knock your system offline (UPS filters spike to ground, leakage current trips GFCI which needs to be manually reset, UPS runs out of battery because no one's home to restore power). This advice is specific to the US & Canada where GFCI's are calibrated to trip at 5 mA. In the UK, their RCD's trip at 30 mA so it's less likely. If you read the fine print for your UPS and/or GFCI they will say not to use them together. What about AFCI's? Well they are basically nuisance devices by design and most electricians hate them. Do not use unless absolutely necessary by code. The difficulty comes into play because UPS's, servers, etc are essentially industrial equipment while the code is written for such common residential usages as plugging in a lamp (where a dog will chew on the cord, a good way to start a fire hence a perceived need for AFCI protection.) What if you're stuck because you want to locate your UPS and equipment in an area where GFCI's are required (like a residential basement)? Well I won't tell you what to do in your own home but I'm sure you can devise a creative solution. :)
daydream 3y ago
What’s the failure mode you’re guarding against by having the UPSs on separate circuits and breakers? Is the idea to protect against a breaker failing, a wiring issue, or something similar?

turtlebits 3y ago

Can't you buy a UPS with a LiFePO battery, or find an old lead acid one and do a battery swap?

cptskippy 3y ago
UPSes with dead lead acid batteries are a dime a dozen. People don't realize or don't both servicing the batteries and toss them out all the time.
- russdill 3y ago
  I love hooking up large lead acid batteries to old UPSes, there's no reason to be limited by the original battery capacity. However...I discovered why some APC UPSes are sealed and the battery cannot be accessed. I was converting one such UPS which had no monitor interface. Having already opened it up to splice in an external battery, I noticed an empty header for a serial port. Cool. Plugged that into my PC and flash/bang/smoke. Fortunately my PC had a good path to ground and was not damaged. But the UPS had some pretty large burn marks at various points in the PCB and was certainly dead. It took me a bit to figure out what I did wrong. The reason it went bang is directly related to why there's no user access to the battery, and why there's no external monitoring port. They went cheap on the electronics and did not include an isolation transformer. Any points within the UPS which are "ground", including the battery negative terminal, are actually referenced to the full bridge rectifier, which provides a direct path to live. Ahh...I'm just very glad I didn't touch any of the battery terminals while I had the thing plugged in.

bongodongobob 3y ago

Nonsense. UPS's don't pose any sort of serious fire risk. UPSs starting on fire are exceedingly rare. Sure, it's probably happened. People get hit by lightning too.

silon42 3y ago
I'd guess they are certainly safer than a laptop, but it depends on a manufacturer... (I've seen lots of "balooned" laptops, including many Macs)
tristor 3y ago
Not to be snarky, but UPS fires are one of the leading causes of datacenter fires: https://duckduckgo.com/?hps=1&q=UPS+Fire+datacenter&ia=web https://duckduckgo.com/?hps=1&q=UPS+Fire+datacenter&ia=web
- bongodongobob 3y ago
  Right and data center fires are extremely rare. Think of how many UPSs are in the wild. The failure by fire rate is probably something like 0.000001%.

deleted 3y ago

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Grazester 3y ago

After using hundreds, hundreds of very cheap to huge expensive APC UPS' I can say I have never experienced a fire. They have all used lead acid batteries, some as heavy as 50lbs. I have even had to cut UPS' open to remove swollen batteries.

dheera 3y ago

Is this specific to Lithium battery UPS units? For home use I bought a lead acid UPS specifically to avoid a fire. For a 5 hour power outage it makes no difference to me if the UPS powers my machine for 5 minutes or 20 minutes; as long as I can save my stuff and shut down it works for me.

wannacboatmovie 3y ago

> I had an electrician run two 20A Dual Function (AFCI+GFCI) circuits Don't do this. This is a terrible idea if you intend to run a UPS. > with hospital grade outlets Complete overkill and waste of money > UPS batteries are a big fire risk No they aren't. Judging by all these incorrect assumptions about electrical, I'd suggest stopping while you're ahead before you burn your own house down.

bloopernova 3y ago
> > I had an electrician run two 20A Dual Function (AFCI+GFCI) circuits > Don't do this. This is a terrible idea if you intend to run a UPS. Can you please elaborate why someone shouldn't do that? (not who you responded to, I'm just curious about the reasoning behind that statement)
- wannacboatmovie 3y ago
  UPS's are notorious for nuisance tripping GFCI's due to the extensive power filtering they usually have inside. It may not happen right away but is dependent on how 'dirty' your power is and on how sensitive your particular brand of GFCI is. All it may take is a neighbour using his AC or power saw and it could generate a spike large enough to knock your system offline (UPS filters spike to ground, leakage current trips GFCI which needs to be manually reset, UPS runs out of battery because no one's home to restore power). This advice is specific to the US & Canada where GFCI's are calibrated to trip at 5 mA. In the UK, their RCD's trip at 30 mA so it's less likely. If you read the fine print for your UPS and/or GFCI they will say not to use them together. What about AFCI's? Well they are basically nuisance devices by design and most electricians hate them. Do not use unless absolutely necessary by code. The difficulty comes into play because UPS's, servers, etc are essentially industrial equipment while the code is written for such common residential usages as plugging in a lamp (where a dog will chew on the cord, a good way to start a fire hence a perceived need for AFCI protection.) What if you're stuck because you want to locate your UPS and equipment in an area where GFCI's are required (like a residential basement)? Well I won't tell you what to do in your own home but I'm sure you can devise a creative solution. :)

daydream 3y ago

What’s the failure mode you’re guarding against by having the UPSs on separate circuits and breakers? Is the idea to protect against a breaker failing, a wiring issue, or something similar?