What Size Breaker for Air Conditioner?
A air conditioner requires a 30A breaker with 10 AWG wire on a 240V dedicated circuit. This is a continuous load — breaker rated at 125% of actual draw.
🔌 Wire Length & Voltage Drop Check
Air Conditioner Wiring Guide — NEC Requirements
Central AC units require a dedicated 240V circuit. Window units under 15A can use a standard 120V/15A circuit. Size breaker per NEC 440.22 based on compressor nameplate MCA (Minimum Circuit Ampacity).
Pro Tip
💡 Check the unit nameplate for MCA and MOP (Maximum Overcurrent Protection). The breaker must not exceed the MOP rating.
Why a 30A Breaker?
The air conditioner draws approximately 30A at 240V (3500W). As a continuous load (3+ hours), NEC 210.20 requires the breaker at 125%: 30A × 1.25 = 37.5A → 30A breaker.
Wire Sizing per NEC 310.16
For a 30A/240V circuit, 10 AWG copper is required per NEC Table 310.16 at 75°C. For runs over 75 feet, upsize to 8 AWG (long runs). Use our Wire Size Calculator and Voltage Drop Calculator.
Complete Parts List
To wire a air conditioner circuit: a 30A double-pole breaker, 10 AWG NM-B cable (Romex) for interior runs or THHN/THWN-2 in conduit for exposed runs, a NEMA 14-30 receptacle (or hardwired), cable clamps, and appropriate junction boxes.
Disclaimer: This guide is for reference only. All electrical work must be performed by or verified by a licensed electrician. Local codes may differ from NEC.