Wow! Window A/C unit amperage

[LD1]

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.

Does it say something like LRA or FLA next to the 7 amp rating?? Cause if so, that would be the max running amps not counting the start-up amperage.

Are you sure your meter is right that it is telling you 15A?? And did you ever check the voltage to see if you are under-volting it?? Cause that would cause a higher amperage reading.

 

[svejkovat]

Many average DMMs will measure amperage up to 10amps. It's easy enough to do with a test cord (plug on one end and bare wires on the other) if you're comfortable with playing with electricity. If you're not, then don't.

I just converted a small extension cord. One of the conductors is cut and just has test lead plugs spliced into it. Ultra simple.

I like that kill-a-watt though.

 

[jonyyuma]

Something is not cool here??Dimming the lights with a 7 amp load???That does Not compute...After 6:00 in the evening the voltage here starts to drag down some. I have read it at 108 volts at peak demand here.A voltage drop can cause the amperage to climb a lot higher.. than at 120 volts..You said it does not trip the breaker.

 

[grsthegreat]

Their can be alot of factors causing this.

1. HOW many rooms are connected to this 15 amp load. I have seen houses that run 4 bedrooms (wall outlets and lights) on one circuit.
2. How far is the run from the panel. There is a thing called voltage drop that can adversely affect amperage draws. I saw this first hand last week. We had a commercial building with a 300 foot run of #12 wire placed on a 20 amp breaker. When they tried to run a 1-1/2 HP motor, it tripped the circuit. Nothing else was run on the wire. I placed an amp meter on the load and found the motor trying to pull 48 amps out of the #12 wire to start the motor. My electronic voltage drop test meter showed me this circuit was having an 18% voltage drop over this distance. On a 120 volt circuit that equated to a 21.6 volt drop, therefore this so called 120 volt circuit was actually only supplying 98.4 volts under load. With that low of voltage, the amperage draw went thru the roof while this motor tried to start and operate. I replaced the wire with the right size for a 5% voltage drop, and the motor fired up and run without any more issues.
3. In new construction, a window A/C units REQUIRES a dedicated, separate 20 amp home run. It cant be used to operate any other device.
4. It can be normal for the lights to dim MOMENTARILY when a large load is started, but they should return to full brightness in a second or two. If they don't return to full brightness, you have a problem that NEEDS to be looked at. Just because your breaker doesn't trip doesn't mean the circuit isn't overloaded. I have physically found wires that are HOT to the touch even though the breaker hasn't tripped. These circuits are overloaded and can cause a fire.

if in doubt.... call an electrical contractor. For a few hundred $$$ you may just save your house.

 

[General Lee]

Does it say something like LRA or FLA next to the 7 amp rating?? Cause if so, that would be the max running amps not counting the start-up amperage.

Are you sure your meter is right that it is telling you 15A?? And did you ever check the voltage to see if you are under-volting it?? Cause that would cause a higher amperage reading.

I don't see LRA or FLA next to any ratings. I just tested the receptacle with a meter, I got 119.8 volts before A/C was turned on. When I started the A/C it dropped to 113.8. The room is all the way at the other end of the house from the where power enters the home. Its a pretty far run.

 

[General Lee]

Their can be alot of factors causing this.

1. HOW many rooms are connected to this 15 amp load. I have seen houses that run 4 bedrooms (wall outlets and lights) on one circuit.
2. How far is the run from the panel. There is a thing called voltage drop that can adversely affect amperage draws. I saw this first hand last week. We had a commercial building with a 300 foot run of #12 wire placed on a 20 amp breaker. When they tried to run a 1-1/2 HP motor, it tripped the circuit. Nothing else was run on the wire. I placed an amp meter on the load and found the motor trying to pull 48 amps out of the #12 wire to start the motor. My electronic voltage drop test meter showed me this circuit was having an 18% voltage drop over this distance. On a 120 volt circuit that equated to a 21.6 volt drop, therefore this so called 120 volt circuit was actually only supplying 98.4 volts under load. With that low of voltage, the amperage draw went thru the roof while this motor tried to start and operate. I replaced the wire with the right size for a 5% voltage drop, and the motor fired up and run without any more issues.
3. In new construction, a window A/C units REQUIRES a dedicated, separate 20 amp home run. It cant be used to operate any other device.
4. It can be normal for the lights to dim MOMENTARILY when a large load is started, but they should return to full brightness in a second or two. If they don't return to full brightness, you have a problem that NEEDS to be looked at. Just because your breaker doesn't trip doesn't mean the circuit isn't overloaded. I have physically found wires that are HOT to the touch even though the breaker hasn't tripped. These circuits are overloaded and can cause a fire.

if in doubt.... call an electrical contractor. For a few hundred $$$ you may just save your house.

Three rooms on the 15 amp breaker, master BR, master bath and a small sun room. My house is approximately 70 feet long. So depending on how the wire is run, it is the farthest from the panel. The wire is 14/2. I'm not sure how to check how amps the unit is pulling with my meter, I just know how to check volts.

 

[k0ua]

Um.. 14 gauge wire.. I always run that for lighting circuits.. not wall outlets.. at 70 feet. um. not good in my book. I am not an electrician, but I would run another circuit just for this AC unit and run it on 12 gauge . Just saying.

James K0UA

 

[MapleLeafFarmer]

I think it should be fine if you minimize use on that circuit of any other high draw appliances. Even avoid 100w lightbulbs and instead keep a supply of 13w or 23w CFL's just for these types of emergancies.

Startup is the issue I believe. amps needed for running an AC is one thing / startup is another.
Box says 15a propbably due to startup requirements.

Not knowing exact model but 8,000 btu likely takes 800w running (6 2/3 amps) BUT on startup depending on the quality of your AC guess that these numbers would momentarily double to 1600w or about 15a.

Keep as much powered down as possible and everything else off if you can at startup.

 

[k0ua]

Here is another idea:.. You mentioned a fairly substantial measured voltage drop at the outlet when the compressor is running. and a normal voltage when it is not.. Here is an idea that wont cost a dime. go to the box and flip the break and take of and remove the wires on this circuit. and go to the box, and do the same and put the wires back on under the screws.. if it is the push in connections on the outlet, use the screws. and put everything back together. The concept is there might just a little high resistance joint on that 14 gauge wire.. causing even more drop than it would normally have. I used an online calculator and you should not be dropping more than 1.5 volts with that setup. Also you may not know how many outlets this runs thru to get to the air conditioner, likely several.. do the same for each one of them. Make sure NOT to use the push in connections on the back of the outlet. Always use the screws and always tighten well. OR.. take my suggestion and run a new circuit with no. 12 wire. Remember I am not an electrician, nor do I play one. Any advice you got from me is worth what you paid for it..

James K0UA

 

[LD1]

Three rooms on the 15 amp breaker, master BR, master bath and a small sun room. My house is approximately 70 feet long. So depending on how the wire is run, it is the farthest from the panel. The wire is 14/2. I'm not sure how to check how amps the unit is pulling with my meter, I just know how to check volts.

SO let me get this straight.

You have not actually checked the amperage, but all you notice is that lights dim when the 7A rated AC unit is turned on on the 15A circuit tying in 3 other rooms???

In all seriousness, I think your AC unit is working properly considering the circuit it is on. But you really need to get an ammeter if you want peice of mind.