What Size Breaker for Electric Furnace?
A electric furnace requires a 60A breaker with 6 AWG wire on a 240V dedicated circuit. This is a continuous load — breaker rated at 125% of actual draw.
🔌 Wire Length & Voltage Drop Check
Electric Furnace Wiring Guide — NEC Requirements
Electric furnaces are continuous loads and may require 40A to 100A circuits depending on heating capacity. Multi-element furnaces may need multiple circuits.
Pro Tip
💡 Check the furnace nameplate for exact amperage. Some units require two separate circuits for different heating elements.
Why a 60A Breaker?
The electric furnace draws approximately 60A at 240V (15000W). As a continuous load (3+ hours), NEC 210.20 requires the breaker at 125%: 60A × 1.25 = 75.0A → 60A breaker.
Wire Sizing per NEC 310.16
For a 60A/240V circuit, 6 AWG copper is required per NEC Table 310.16 at 75°C. For runs over 75 feet, upsize to 4 AWG. Use our Wire Size Calculator and Voltage Drop Calculator.
Complete Parts List
To wire a electric furnace circuit: a 60A double-pole breaker, 6 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.