What Size Breaker for Sauna Heater?
A sauna heater requires a 40A breaker with 8 AWG wire on a 240V dedicated circuit. This is a continuous load — breaker rated at 125% of actual draw.
🔌 Wire Length & Voltage Drop Check
Sauna Heater Wiring Guide — NEC Requirements
Home sauna heaters range from 4.5kW to 12kW. A 6kW heater draws 25A at 240V — as a continuous load, requires a 40A breaker (25A × 125% = 31.25A → 40A).
Pro Tip
💡 Sauna wiring must be rated for high temperature. Use high-temp rated conductors within the sauna room.
Why a 40A Breaker?
The sauna heater draws approximately 30A at 240V (6000W). As a continuous load (3+ hours), NEC 210.20 requires the breaker at 125%: 30A × 1.25 = 37.5A → 40A breaker.
Wire Sizing per NEC 310.16
For a 40A/240V circuit, 8 AWG copper is required per NEC Table 310.16 at 75°C. For runs over 75 feet, upsize to 6 AWG. Use our Wire Size Calculator and Voltage Drop Calculator.
Complete Parts List
To wire a sauna heater circuit: a 40A double-pole breaker, 8 AWG NM-B cable (Romex) for interior runs or THHN/THWN-2 in conduit for exposed runs, a NEMA 14-50 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.