What Size Wire for a Central Air Conditioner?
Wire and breaker sizing for a Central Air Conditioner — the typical 240V circuit, plus the code details (NEC Article 440) that change the answer.
Calculations are built on the 2023 National Electrical Code (NEC) and cross-checked against the published code tables. How we verify. Last reviewed June 2026.
On a 30A 240V circuit at 75°C terminations.
Protected by a 30A breaker (NEC 240.6).
Central Air Conditioner current varies by model. The size above is the common case — always size the conductor to the unit’s nameplate rating / Minimum Circuit Ampacity (MCA) and protect it at the labeled maximum breaker/fuse.
Central Air Conditioner Circuit Details
- Air conditioners are sized to the nameplate Minimum Circuit Ampacity (MCA) and protected at the Maximum Overcurrent Protection (MOCP), per NEC 440.
- Typical 2–5 ton units land on 20–40A circuits (12–8 AWG copper).
- Use the MCA for the wire and the MOCP (usually a labeled max breaker/fuse) for protection — they are not the same number.
Long run to your central air conditioner?
Over distance, voltage drop can require a larger wire than the table above. See the 30A wire size by distance:
Size it for your exact install
Open the calculator pre-filled with 30A at 240V to add distance, material and temperature.