A ups already does surge, ripple and brown out protection making a surge protector pointless

The question is more about whether it is safe. After all, if I'm trying to add outlets to my UPS and all I have is a surge protector lying around, I'm not thinking about pointless, I'm thinking about adding outlets. I have read that having a surge protector plugged into a UPS can lead to unsafe electrical conditions. Given the strong electrical/electronic background of many of the folks here, I wanted to get some opinions.

I wanted to know too. So a quick google i see a apc faq: http://www.apc.com/us/en/faqs/FA158852/

Will read myself after looking up more retro pi crap.

RogueTrip2012 wrote:

I wanted to know too. So a quick google i see a apc faq: http://www.apc.com/us/en/faqs/FA158852/

Will read myself after looking up more retro pi crap.

Yeah, I've seen that APC faq. I just don't know how accurate it is (depending on whether engineering or marketing was more involved). I just edited the Subject and reworded the body of the OP because I didn't do the best job of it on the first go. Thanks!

It should work it's just redundant protection, the only problem i see there is that you shouldn't overload the UPS with what it can handle.

To me it sounds like they suggest using strips without any surge protection or filtering just in case, because usually one cannot tell if the strip has pure surge protection or maybe other filtering as well.

If the power strip only has pure overvoltage surge protection (TVS, MOV, GDT), I think it should work.

However, if the power strip has any other kind of filtering (meaning common mode chokes, coils, capacitors, etc), then basically what the appnote says that they cannot guarantee if the UPS will work with the given load correctly when there is extra stuff in the power strip.

The problem is, you don't know what's inside your power strip. Unless you can open it and put it back together. And you know what the components inside are. So that's why they say it is just better not to use anything than normal power strips.

Personally I would want all of my crap devices off a power strip or surge protected power strip and my most important devices on a UPS.

If you have a surge power strip plugged into an UPS then there is the possibility of overload AND when there is a surge then it's being tripped on both devices instead of just one and the energy has to go somewhere. So if the surge power strip is no longer effective then where is that energy going to go? (More than likely the strip wouldn't have done anything anyway, they are mostly effective for the small surges not lightning strikes)

Also the MOV in the device is a factor. It's much cheaper to replace a strip than an UPS. You really don't know if the effectiveness is still the same as when the power strip was brand new but more than likely the UPS would be far more effective than the strip when a surge occurs.

Just use a regular power strip, assuming you can find a regular power strip and not a surge power strip and if you use a regular power strip don't overload your UPS. If you have all of the slots filled then more than likely it's overloaded.

I've also noticed with my own and others usage of power strips plugged into UPS that it's very easy to just plug a random device into the UPS if there's a power strip attached to it. (Vacuums, space heaters etc) The plugs become disorganized after time, devices plugged into battery side that should not be and vice versa. I'm sure you're the exception to this of course.

Also, there's the cost issue. Plain power strips are dirt cheap, and once the plug has been removed and replaced with an IEC C14 connector (at least in the UK) for use in the UPS, it's a pain to use the sure protected strip outside the UPS.

Also consider how surge suppressors work. Most of them deal with excess voltage by shorting to ground until the voltage returns to normal. Depending on the UPS design this can mean either the UPS sees a short circuit/overload and completely shuts off, or if it's completely isolated then nothing might happen because the ground line isn't really part of the circuit. In this case the surge suppressor wouldn't suppress anything, so you might have a false sense of security, thinking your devices are protected when in fact they aren't.

However when you consider that small surges can happen as devices are turned on and off, if you are really unlucky, then you might find that sometimes when you switch something on or off, your whole UPS shuts off taking everything down with it, thanks to the surge suppressor triggering the UPS' short circuit protection.

Personally I have my UPS plugged into a surge suppressor because it doesn't really matter on the input (a bit redundant but no harm done) however on the UPS output I make sure to use plain power boards and rack PDUs so as not to inadvertently kill the load thanks to a surge suppressor with good intentions.