Wow! Window A/C unit amperage

General Lee · Jul 2, 2012

In light of another extended power outage, I added to my preps in order be more comfortable during summer outages. I picked a Kenmore 8,000btu window A/C unit to be able to cool one room during an outage. I installed it today to test it out and I am considering using when I sleep as I like cool temps when sleeping. I fire it up and when the compressor kicked on it dimmed the lights in the room for a second and appeared they never reached their full brightness after the flicker (It was hard to tell)

I said "Good Googly Moogly", how much power is this little AC unit calling for. I haven't found the wattage but its 15 amps. Well the room its in is on a 15 amp breaker. I ran it for a hour or so and no breaker tripped, but I'm concerned running it for long periods while I sleep. My big window unit in the garage is 14,000btu and only 12.8 amps / 1380 watts.

My question is, nothing will be on while I sleep except maybe a fan, is it safe to run this unit on the 15 amp breaker? I don't want no long and slow breaker pop cause wires will be getting warm at that point. But for the time I ran it to test it the breaker held. Is there any lee-way here? Maybe the breaker held long enough for the compressor to stabilize and running watts/amps is lower. Is this common for these little window shakers? I didn't think an 8,000btu would draw that much.

RobertBrown · Jul 2, 2012

What is the wire size and how long is the run? Do you have any 14 gauge wire in the circuit?
check the voltage at the receptacle before and after the compressor comes on. You may have relatively low voltage to begin with.
Doesn't say where you live but some parts of the country are experiencing power issues with all of the consumption due to the heat. I guess everybody is using their air conditioners.

MikeInEburg · Jul 2, 2012

If your generator has the capacity, running the new unit shouldn't be a problem. Keep an eye on voltage drop

LD1 · Jul 2, 2012

There should be a nameplate on the AC unit that lists the FLA. If you are drawing more than that, either you are supplying low voltage or there is something wrong with the unit.

There are 3.41 BTU's per watt, and a compressor sould be in the 3x's efficency range.

So your 8,000BTU AC unit is roughly 2350 watts worth of cooling. Since it sould be 3x's eff., it "should" only be pulling around 780 watts, and on a 120v line, that is about 6.5A.

Your other unit is spot on. And my garage unit is 24000BTU and pulls 9.5A @ 240V (2280w).

As others mentioned, check the voltage. Also check the nameplate as I already mentioned. An 8000BTU 120v AC unit shouldnt be anywhere near 15A

timster2 · Jul 2, 2012

This is my favorite tool for answering these questions P3 - Kill A Watt. I have used this to check frequency and adjust my generator as well as measure loads and KWHR. For about twenty bucks its well worth it.

dex3361 · Jul 2, 2012

I am currently out of power due to the storms and I went the same route that you are considering. I chose a 12K BTU unit and it is pulling a little under 10 amps even though the box has a big 15 Amp label on it. It has been running continuously since Friday evening when the storms hit. I did't put the AC unit in till Saturday morning though.

Larry Caldwell · Jul 2, 2012

A breaker is rated to trip at maximum current, but only rated for 80% of maximum for a constant load. A 15 amp circuit will only supply 12 amps constant. Your bedroom was wired to the minimum code, which isn't enough to run appliances. It may work, but you may also find your breaker breaking down and tripping all the time. Don't put anything else on that circuit.

tallyho8 · Jul 2, 2012

If your 8000 btu unit uses 15 amps it must be a very old unit because no new units use 15 amps. Since most new units only use about 6 or 7 amps it would be worth it for you to throw that clunker away and get a new unit. The money you save in electric bills would easily pay for the new unit this year.

Then again, it may be new and may not use 15 amps. You may have read the rating wrong and seen that it says its rated at 15 amps and to use a 15 amp breaker. Since this is the smallest breaker in use even a 5 amp unit says to use a 15 amp breaker.

If it's new you need to check your wiring. If its used cleaning the condenser coil may reduce the amperage draw.

General Lee · Jul 2, 2012

Tallyho- it's a brand new unit. I agree a new unit shouldn't pull that much.

Robertbrown- yes I believe my wiring is 14 guage (probably standard)

General Lee · Jul 2, 2012

LD1- I checked the nameplate label, it's 7 amps and 740 watts so you were darn close. I wonder if that is in efficiency mode? The unit has a efficiency setting on it but I don't plan on using it because it cuts the compressor on and off alot.