First off
AC units require a lot of power, so they should not share a circuit with other appliances or other loads and equipment. Refrigerators, computers, washing machines and water heaters are examples of power-hungry appliances.
With very few exceptions, a central air conditioner requires a dedicated 220-240 volt circuit. If you are installing a window air conditioner it will likely plug into a standard 120-volt outlet. It may or may not require a standalone circuit, meaning its own circuit breaker.
It must be on the same level and located within 25 feet (7.5 m) of the HACR equipment. For example, an air-conditioning unit is located on the side of a one-family dwelling. The required outdoor receptacles on the front and back of the house are more than 25 feet from the air-conditioning unit.
Circuit breakers are designed to protect your home's electrical system by shutting down when an overload occurs. Your air conditioner needs its own circuit to avoid overloading the circuit and creating a safety hazard.
Most central air-conditioner systems incorporate two circuit breakers. One protects interior components such as the air handler/blower fan inside the house. Another circuit breaker protects the outdoor condenser unit, including the compressor.
To withstand the high current, a thicker wire is required (typically 16–20A, 240V rating). Also, the connections are made such that no power is drawn by the ac if main supply is cutoff and auxiliary supply (eg. Inverters, DG) are on. Hence, yes, the AC because of its high power requirements, needs separate wiring.
NEC Section 210.63 requires a 125-volt, single-phase, 15- or 20-ampere-rated service receptacle located within 25 feet of the following: Heating, air-conditioning, and refrigeration equipment (other than evaporative coolers for one- and two-family dwellings)
Alternating current (AC) power is the standard electricity format from outlets.
It runs on 110 volts. Just plug it in to a normal outlet.
You can instal 2 ACs on one breaker, but in the long run, it can be risky. Hence, it is always encouraged that you go for another separate circuit or breaker for your second AC. So before installing 2 aircon in 1 breaker, seek an electrician's advice.
To see if you have dedicated circuits, check your breaker box for labels on the circuit breakers that correspond to specific appliances. If they're not labeled, you can turn off all but one breaker and test the outlets to see which ones lose power.
A single outlet usually limits you to plugging in two to three devices which may not always be convenient. Power strips, also known as surge protectors, contain multiple outlets so you can power several more devices all from the same source.
The case of an AC unit should always be grounded. Older houses (prior to about 1965) in the US had 2 prong(Hot and Neutral) outlets. In some juristictions (such as New York City) the house is wired with armored cable (either the current “Type AC or the older, and somewhat dangerous “Type BX”).
“Like all major appliances, these devices should be plugged directly into a wall outlet. They can overload a power strip or extension cord and cause a fire.”
Your air conditioner's chosen spot needs a power source, and it's important to make sure that your new unit has the right plug to match its nearby air conditioner outlet. The 110 volt, 15 amp plug is the most common.
The common household outlet, known as a duplex receptacle, is typically designed to handle 15 or 20 amps of current at 120 volts, yielding a maximum capacity of 1800 or 2400 watts, respectively. This capacity is suitable for most everyday appliances and devices such as lamps, chargers, computers, and TVs.
NEC Section 210.52(a)(1) (aka 6'-12' rule): Receptacles shall be installed such that no point measured horizontally along the floor line of any wall space is more than 6' from a receptacle outlet..
Common HVAC-related codes and standards include ASHRAE 90.1, ICC International Energy Conservation Code (IECC), NFPA 70 – National Electric Code (NEC), and UMC Uniform Mechanical Code (UMC). HVAC systems must adhere to these codes and standards in order to be considered safe, reliable, and energy efficient.
The receptacle shall be located on the same level and within 7.5 m (25 ft) of the heating, air-conditioning, and refrigeration equipment. The receptacle outlet shall not be connected to the load side of the equipment disconnecting means. Informational Note: See 210.8 for ground-fault circuit-interrupter requirements.
That's why 3-phase power is so popular and is used for things like data centers and other power-hungry operations. It lets you transfer the same amount of power with less wiring, in some cases 50% less (using 3 wires instead of 6).
Both 10/2 and 10/3 have a wire gauge of 10, which is suitable for most air conditioner installations.
Additionally, in many places, it is more than a recommendation to have a disconnect switch for your air conditioning unit, it is required by law. The National Electrical Code states that all HVAC systems must have a readily accessible method for disconnecting from electrical power.