What Size Wire for Microwave (Built-in/OTR)? — Complete Wiring Guide
A Microwave (Built-in/OTR) requires 12 AWG copper with a 20A on a 120V dedicated circuit. Here is the complete NEC-compliant wiring guide.
Microwave (Built-in/OTR) Wiring Details
Built-in and over-the-range microwaves draw 12-15 amps and should have a dedicated 20A circuit. Countertop microwaves can share a kitchen small appliance circuit, but the dedicated approach prevents nuisance tripping when running the microwave and toaster simultaneously. Use 12/2 NM-B cable from a 20A breaker to a receptacle behind the microwave location.
NEC Code Reference
The wiring requirements for a Microwave (Built-in/OTR) are governed by NEC 210.52(B)(1). Always check the appliance nameplate for specific electrical requirements — the manufacturer's specifications take precedence over general guidelines. Your local AHJ (Authority Having Jurisdiction) may have additional requirements beyond the NEC.
Pro Tip
Over-the-range microwaves also serve as range hoods. When running the vent fan and microwave simultaneously at full power, the draw can briefly exceed 15A. This is why a dedicated 20A circuit is strongly recommended even though NEC technically allows the microwave to share a small appliance circuit.
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.