Running a Home-Office Through a UPS

mwagner_00 asks: "After spending lots of money and time, I now have an office in my home. My wife and I both have computers (mine is a high powered gaming rig), and I also have a workbench where I work on other people's PCs. I have a web/email server as well. I would like to protect the investment by running the room's power through a UPS. I have a APC 3000NET that my workplace was going to throw out. The only thing it needs is a good set of batteries. Has anyone tried something like this before? Basically I want to find the breaker for the room, and after the breaker, run the power through the UPS and back out to the room. Is the UPS that I have sufficient to run a whole small office?"

Specific loads....

[karnal]

First off, you do not want to put the UPS in like that for the whole room. I'd say if you really want to put it in in this fashion, make dedicated circuits (like in some datacenters) beside the regular circuits that are UPS'd. That way you have a choice of outlets... Anyways...

You kind of need to specify the kind of loads you'd like to put on the UPS. What you'd need to do is look at how many machines, how many monitors, etc.

For instance, you do NOT want to put lighting (flourescent or otherwise) on a UPS.

I have an older APC 900 that has external modules that I can add battery packs to, if I want a long runtime.

I'm rambling, but a 3000 will power a lot of equipment, for a short amount of time. The batteries for the "higher numbered" UPS's seem to be pretty small, so you don't get much runtime out of them. For a quick-and-dirty of how long, get an estimated wattage you're going to draw from the UPS. Then, take battery voltage, multiply by number of batteries in the UPS, then multiply by the AH of ONE battery. That gives you the watt-hours of your UPS.

If you're going to draw 450 watts from a UPS and the batteries add up to 450 or so, then you'll get about 1 hour - 20%.... Efficiency losses run about 20% (I'm guessing here)...

Anywho. My 900 runs a file server, switch, cable modem, sipura phone box, and the gateway for about 2 hours. It only has one battery pack, but my battery packs are 4x(12v*18AH), which is around 864Watt Hours. So I'm probably drawing 400 watts continuously through the UPS....

Keep in mind

[Guspaz]

Line-interactive UPS units like the 3000NET DO NOT filter power. They have AVR, which only filters huge changes in voltage. It will not kick in for even extremely dirty power. It is simply meant to boost up the voltage if your power drops down to, say, 90 volts, or goes up to 150 volts.

So keep in mind that really all the UPS is going to give you that a good power supply can't is battery backup and surge protection.

What you really want

[ReverendRyan]

If you're trying to keep working during a blackout (as opposed to keeping your RAID consistent), look into these: a Kohler Generator [kohlerpowersystems.com]. Sure, you still need a small UPS for your server/desktop, but it only has to last ~45 seconds until the generator kicks in. Have an electrician (or authorized Kohler rep) install it. I wish I had one sometimes.

YMMV

That's a REALLY bad idea...

[HaloZero]

...for a couple of reasons. Firstly, you don't want to run the entire room off of the UPS; just your critical computer equipment. My UPS runs my workstation, the router, one display monitor, and typically a linux file/web/services server. It also runs my desk lamp. The UPS I use in particular is nice (and I believe mine is related to yours, in brand) because it has this warning alarm when it's power becomes the primary source of energy. The reason for this is that my particular outlet (I live in an apartment with three other people) is wired to a pair of lightswitches on anterior corners of my desk. We've also noticed that when you turn something on in one part of the apartment, the power will occasionally spike, and without the UPS, reset someone's workstation. But I digress, don't plug the whole room into your UPS. Just what you need on to perform an adequate shutdown of your equipment, in the event of a power failure. Secondly, if you put the UPS on the source side of your breaker, and your house gets struck by lightning, your UPS is going to BLOW UP. And I don't want to be anywhere near it if and when that happens. Circuit breakers are there for a reason. Sure, they aren't the end of the line in protection, you need a surge protector, too. Now, my UPS does have a surge protector in it, but still, I'm sure you see my point by now.

Re:Just go PV

[geoffspear]

Repeat after me: a watt is a unit of power, not of energy.

Do you mean you can generate a megawatt hour every year, or you can constantly have an output of 1 million watts for a year?

Re:Just go PV

[Intron]

There was just an article on this in one of the pop science magazines. PV cells pay back about 7 times their energy cost to build. Wind turbines only pay back about 5 times. Corn-based ethanol is currently the worst energy source out there, costing 1.3 liters of oil per liter produced, about the same ratio as hydrogen produced using electrolysis.

Best energy sources (in terms of payback and renewability) are wood heat (1:22) and hydroelectric power (1:28). They didn't cover nuclear, since it isn't an option in the current political climate.