Air Conditioner/Electrical

OK, any electricians out there?

I’m doing my work in an upstairs office in my 2-story house. As we enter summer, my central air wasn’t really able to keep this room cool without setting the overall temp so low that the downstairs would be super cold - both inefficient and uncomfortable for the rest of my family who mainly hangs out downstairs during the day.

So I bought a 6000 btu Whirlpool window air conditioner for my office as supplemental cooling. It works well, but…

Every time the A/C’s condenser kicks in, there’s a noticeable power flicker/brownout (i.e. the lights dim for a half second). One time this was also severe enough to reset the Tivo downstairs, and it seems to be causing other mayhem, too.

Our house was built in '95, so the electrical systems should be reasonably modern.

So is this likely the result of a poorly designed A/C (i.e. I should return it for a different brand), or do I need some kind of electrical upgrade for this (i.e. call in the electrician)? Anybody else ever have similar issues?

This definitely isn’t a problem with the AC. At most it should be able to take out the breaker it is on. If it’s screwing up the whole house, that says bad things about your wiring. Get an electrician.

I’m not totally sure that the Tivo going out was because of the A/C.

The lighting flickers when the condensor kicks in only seem to happen in my office, which is perhaps on the same breaker as the A/C (hard for me to tell, as the breakers are poorly labeled)

The AC hasn’t actually tripped the breaker yet, FWIW.

Well ya, most likely the room is on the same breaker, and the AC hasn’t put enough watts through yet to blow that breaker… But if you suspect that it did the thing with the tivo, then you may have a real problem.

You could always (and probably should) just get a cheapo UPS to stop the brownouts from screwing up your PC (which they can).

The TiVo may or may not be related to the A/C. It would have to be on the same circuit to cause a problem. Given the age of your wiring, I’d guess that it is wired to 1 room/circuit.

The problem you’re having is that starting up the condenser draws a lot of amperage, much more so than just running it, so the current drain is getting close to the limit for the breaker but not quite enough to trip it. You have two solutions. You can get a UPS to protect the computer (because periodic power dips will damage it over time) or call in an electrician to run a new circuit up for the A/C. The latter is probably the better approach and shouldn’t cost too much (depending on how hard it is to run the wires through the existing walls).

I use to have a crappy Air Conditioner in my old apartment, and it would reset the breaker all the time. Be careful when this happens… The wiring in my building was really old stuff. When I touched the wall above the power outlet, it would be warm… Eventually it shorted out the wire.

One suggestion, is to get an APC or other brand UPS. Plug the AC into that. When the condensor kicks on, the UPS will handle the overload. You just need to make sure you have one with enough watts.


Umm… no, dude. You can’t plug a major appliance into a UPS. That is a very very very bad idea.

Now plugging the tivo into the UPS, that’s a good idea.

You can plug a major appliance into a UPS if the UPS is big enough. It just has to match watts/amps. I’m not talking about one of those crappy under the desk jobs. Your standard 3-prong 110 volt air conditioner can work just fine on a UPS. Your fuse box probably has the whole room at… What… 12 amps? Your large UPS can handle that.


Sustained yes, but when the compressor kicks in it will spike very high. No doubt you could get a UPS big enough to handle it, but it would be extremely expensive and is… well, a pretty stupid idea really, no other way to say it. Get a cheap 280VA for the tivo instead.

Yea, it’s a much better idea to let the compressor blow out your whole electrical system in your house so you can save the Tivo. Brilliant. When the air conditioner’s compressor kicks on, the UPS provides balanced power by giving the air conditioner the extra load it needs from the battery, while keeping the electrical current from the outlet steady and not overloading your fuse box.

Well, at least your way you’ll still get to record your TV shows while you sit in the dark.


Modern home construction is such ass I can’t stand it. With the housing situation the way it is there’s almost no room to negotiate on shit.

I pretty much have to wire all my shit the way I want, particularly basements. Multiple 20A circuits into every room, etc. Then again, I run a lot of electronics gear.

I’d recommend what one of the earlier posters said, and that is to run a separate circuit for the AC unit. Probably be a few hundred bucks, but well worth the peace of mind. And always have a UPS for your PC no matter what.

Of course, the ideal situation, assuming you’re not in just a converted attic, would be to install separate HVAC zone for the second floor. If it’s small enough then the AC unit effectively does that, but if you have other rooms, then a new heat pump + vents/airways + thermostat can seriously help balance out the home’s heating cooling.

My current house has 3 separate zones (basement, 1st, and 2nd), and it’s still gets unbalanced on occasion due to sun angles (half the upstairs is nice and cold, the other half is unbearably hot since it gets full brunt of the sun).

Do stay away from a UPS for the A/C. They’re not designed to handle the current that the A/C will draw on startup. If you read a UPS manual, you’ll see that they specifically tell you not to plug laser printers and scanners into the UPS slots for the same reason.

Going to do Epic Necromancy here.

My AC just broke. 3-4 days minimum to fix.

How good are ventless AC units, Figured if I could spend $200-300 for one, and get a room cool enough to sleep in, I’d be fine- I only live in one room really, and my downstairs isn’t too hot.

There’s no such thing, unless you’re talking about evaporative cooling which only works in very dry climates. You can’t “make cold” due to those pesky laws of physics.

I think he means the stand-alone AC units that don’t have to go in a window? The ones that stand in thee room and cycle air through them but don’t vent it outside? I’ve seen some like that, but know zip about them.

That is impossible. You can’t make cold.

All of these do vent through a window, using a spacer placed in the window with openings for the vents. The exception is the swamp/evap coolers @stusser mentioned.

I’ve seen swamp coolers, out in Arizona; those things are kind of nasty!

Ah, ok. I was just looking at the pictures, not seeing the big vent pipe out the back of these things. If I had thought about it, yeah, it ain’t feasible otherwise.

Oh, yes, the free-standing A/Cs work, but they aren’t ventless, waste heat still needs to be exhausted outside your house. They are inefficient compared to a standard window A/C but they do work and fine to holdover for a couple of days.

I have no experience with it personally, but saw this come up the other day.