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.