The current draw of air conditioners is rated in amperes or amps -- the basic unit of electricity that is equal to a constant current draw. Air conditioners are rated on their cooling properties, as measured in British thermal units, or BTUs. The larger the BTU number, the more amps the air conditioner will draw. However, amperage draw differs with standard voltages like 115 volts and 230 volts and whole-house central air conditioning.
Room Size Small 115 Volt Air Conditioners
Small room-size air conditioners, generally in the 5,000 to 6,000 BTU range, will draw between 5 and 7 amps of power. In most cases, these are plugged into a wall socket that is serviced by a 15 amp breaker. Because the amperage draw is low, other small household appliances can use the same socket as the air conditioner.
Room Size Large 115 Volt Air Conditioners
Large room-size air conditioners are typically rated from 8,000 BTUs up to 12,000 BTUs, although some modern types may even reach 15,000 BTUs. These air conditioners draw 10 amps or more and must be plugged into a dedicated outlet. If any other appliance is plugged into the same outlet, the breaker will not be able to support the added amperage and it will trip the circuit.
230 Volt Air Conditioners
Air conditioners of 230 volts use a dedicated higher voltage circuit, much like the type that powers an oven or electric clothes dryer. Because the voltage is higher, they generally draw less amperage than their 115 volt counterparts, but they also need a specific outlet to support their higher voltage needs. For example, an 18,000 BTU 230-volt air conditioner draws approximately 8 amps of power. Air conditioners of this voltage are considered permanently mounted, even if they are window models, because a special 230 volt outlet will be installed at the point of use. Because of that special need, they cannot be readily carried around from window to window and plugged into any standard 115 volt outlet.
Central Air Conditioning
Central air conditioning also runs on 230 volts. However, because they are permanently mounted, central air units are hard-wired into your electrical box. A typical 2-ton central air unit that puts out 24,000 BTUs will draw between 15 and 20 amps.