What Size Breaker for Window Air Conditioner?
A window air conditioner requires a 15A breaker with 14 AWG wire on a 120V dedicated (for large units) circuit. This is a continuous load — breaker rated at 125% of actual draw.
🔌 Wire Length & Voltage Drop Check
Window Air Conditioner Wiring Guide — NEC Requirements
Small window ACs (5,000-8,000 BTU) draw 5-8A and can share a 15A circuit. Large units (12,000-18,000 BTU) draw 10-15A and should have a dedicated circuit.
Pro Tip
💡 Per NEC 440.62, a room AC on an individual branch circuit can have cord-connected LCDI (Leakage Current Detection and Interruption) protection.
Why a 15A Breaker?
The window air conditioner draws approximately 10A at 120V (1200W). As a continuous load (3+ hours), NEC 210.20 requires the breaker at 125%: 10A × 1.25 = 12.5A → 15A breaker.
Wire Sizing per NEC 310.16
For a 15A/120V circuit, 14 AWG copper is required per NEC Table 310.16 at 75°C. For runs over 75 feet, upsize to 12 AWG. Use our Wire Size Calculator and Voltage Drop Calculator.
Complete Parts List
To wire a window air conditioner circuit: a 15A single-pole breaker, 14 AWG NM-B cable (Romex) for interior runs or THHN/THWN-2 in conduit for exposed runs, a NEMA 5-15 or 5-20 receptacle, 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.