The central AC in our apartment is not working effectively in the summer; we are running the AC continuously for 14 hours a day to keep the temperature below 80 degrees. As you can imagine, our electric bill has become a huge problem. (Edit: Please note the maintenance staff are incompetent and management doesn't care about our problem at all -"getting the central AC fixed" is not an option, if it's even fixable) I bought a used portable AC unit (around 11,000 BTU, rated at 12 amps) and plugged it into an arbitrary outlet near a window, because I was always able to do so with a similar AC at my parent's house. The portable unit worked great for a couple of minutes and then tripped the circuit breaker, which also shut off my computer. After a lot of testing I have determined that all of the outlets in the two bedrooms and in the living room run off a single 15-amp circuit (which was 'helpfully' labeled "lighting" in the circuit box). This rules out every outlet that is within reach of a window.

There are two circuits labeled "plugs" in the circuit breaker, but AFAICT they aren't connected to anything (unless they're for the outlets in the kitchen). Obviously because it's an apartment I can't do anything with the wiring, and I can't use an extension cord on an 11,000 BTU AC... Am I screwed here? Is this typical for an apartment with central AC? The full set of circuits is (as they are labeled): Lights: 1x15A (again, this actually covers outlet in 3 rooms, there is no overhead lighting) Garbage Disposal: 15A (nowhere near a window) Dishwasher: 15A (nowhere near a window) Electic Range: 2 x 40A (oven/stove) We resolved the problem with the portable AC by purchasing a heavy-duty, 15-amp, 12-gauge extension cord and running it from the bathroom to the AC by the window. Since the bathroom is on its own circuit, the AC does not trip the breaker. A big thank you to those who suggested this in the comments. Ironically, management has decided to replace our central air conditioner after I discovered mold in the unit, and their subsequent inspection also revealed it to have a serious Freon leak.

If you test each outlet, and find a drop in voltage on any of them, you might be able to claim that the wiring does not meet code, and force the landlord to make some changes that way. (NEC 210-19 FPN No. 4) in the National Electrical Code states that a voltage drop of 5% at the furthest receptacle in a branch wiring circuit is acceptable for normal efficiency. In a 120 volt 15 ampere circuit, this means that there should be no more than a 6 volt drop (114 volts) at the furthest outlet when the circuit is fully loaded. It also means that the circuit has a resistance that does not exceed 0.4 ohms. This answer was not applicable since the OP had an older 15 amp circuit in the bathroom and not a 20 amp circuit as is required in modern residential wiring. I have therefore withdrawn it.Browse other questions tagged electrical air-conditioning or ask your own question. AC Unit Maximum Breaker Re: AC Unit Maximum Breaker Is this new construction? Because it is only 5 amps I would look closely at the wire and insure that it is rated for the higher amperage under an inductive load.

It may be wrong IAW the Mfg. but an over current device is there to protect the wire on the branch not the appliance. If the wire to the unit is rated for the breaker size at least you won't have a fire hazzard to the unit. Also a concern is if the breaker is rated for HVAC use.ahu air handling unit คือ Also consider that the condenser may have internal wiring matched to the Max Fuse/Breaker Rating indicated on the label, and an older oversized breaker may not trip if the compressor motor locks up ... which could complete fry the equipment ...2.5 ton ac unit how many watts IMO report it as a defect needing evaluation/repair and call it a day ...kuhl ac unit every HVAC guy and electrician I speak to say it is alright to go to the next 5 amp size.

They want to see that the wire size is consistent with the higher size. None of them will change the breaker when called out to confirm this. At ITA I remember them saying that the wire size can be smaller if matched to the minimum ampacity rating on the dataplate. Being an HVAC tech for a long time that is what would happen. The tech will say no problem. As long as the breaker is correct for the wire size 5 amps isn't a big deal. Start up amps can be in the 60-amp range. I've seen units under this same scenario (25 amp nameplate) that would cause nuisance trips when a 25-amp breaker was installed and when the 30-amp breaker was put in the trips stopped and there were never any problems. It is over fused if a breaker larger than the manufacturer's label calls for is installed. Here is a good explanation I picked up somewhere: A/C condensers contain a hermetically sealed compressor motor as well as a fan to circulate air across the coils. The rules for protection to motor circuits are different than for circuits with simple resistive loads.

When a motor first starts , it draws a much higher amount of current than it does after it is running. The high "inrush" current can exceed the rating of a breaker or fuse sized to protect the wire. The inrush current lasts typically only about 6 electrical cycles, or 1/10th of a second - less time than it would take to damage the wire or its insulation. However, if the overcurrent device is sized to protect the wire against overloads, the device might trip, and the machine would not be able to start. Motor circuits get around this problem by dividing the two separate functions of an overcurrent protection device. "Overloads" are currents that can damage a circuit if allowed to continue for a sufficient time, whereas "short circuits" and "ground faults" are high currents that can cause immediate damage. Large motors and air conditioners separate these overcurrent functions. The breaker or fuse ahead of the air conditioner only protects against short circuits and ground faults. Overload protection is built into the compressor itself.

The wire to a condensing unit must be large enough to allow the equipment to start. The device is therefore NOT sized to protect the wire against overloads. It is not uncommon to see a 50 Amp breaker on a #10 wire. The wire is protected against overloading by a separate thermal protection inside the compressor. How do we know what the motor requires for wire size and proper fuse/breaker protection? It's all on the mfg. label attached to the appliance. If the label calls for fuses, there MUST be a fuse in the disconnecting means, not a circuit breaker. If the label calls for a "HACR" type breaker (Heating, Air Conditioning and Refrigeration), then that is the type of breaker that must be used. If the label simply states "maximum sized over current protection" then any form of overcurrent protection may be used. The HACR designation is not always visible on a circuit breaker once it is installed inside a panel or disconnect. Note on the label taken from a Lennox A/C data plate:

FUSE - 25 UL (CSA is a Canadian standard. We use UL in the U. S.)UL - Not allowed in U. S. All this means is the MINIMUM wire size required is #12 (solid copper); the MAXIMUM rating of a fuse (if a fuse is used) must be 25 amps and the MAXIMUM rating of a circuit breaker (if used) must be 25 amps AND the breaker must be a HACR type.However, if the over current device is sized to protect the wire against overloads, the device might trip, and the machine would not be able to start. "it draws a much higher amount of current than it does after it is running." This is called an inductive load. "The high "inrush" current can exceed the rating of a breaker or fuse sized to protect the wire. " This is why HVAC breakers must be rated for HVAC use. The wire, breaker (to protect the wire), and type of breaker must be correct and is reflected in the "minimum circuit data". Michael MerinoMerino's Home Inspection & Education Inc." Originally Posted by jpope

I understand that the circuit is over-fused, but the appliance is connected to that circuit. If for some reason it were to draw more than 30 amps (outside of the inductive load) the breaker will not trip. I am confused by the differing opinions. I have been told by inspectors it is OK, and some say it is not. Some say that you can over-fuse the AC up to 40%. I do not seem to be able to find a definitive answer. I am thinking that if the max breaker is supposed to be 30 amp, then the breaker should be 30 amp not 50 amp, even if the conductor is the proper size. Professional Certified Master Inspector In Edwardsville, Glen Carbon, Godfrey, Maryville, Fairview Heights, O'Fallon and surrounding areas of Illinois Metro-East Need a home inspection in South Dakota? listing of South Dakota certified home inspectors. As a Professional Home Inspector, I support the privacy of my clients. Services provided in East MN and West WI Originally Posted by ccurrins There is not a fuse in the disconnect.