Built-in and over-the-range microwaves should have a dedicated 20A, 120V circuit. Countertop models can share a kitchen small-appliance circuit.
| Recommended wire | 12/2 NM-B with ground |
| Breaker | 20A single-pole |
| Voltage | 120V |
| Typical amperage | 12A |
| Circuit amperage | 20A |
| NEC reference | NEC 210.52 |
| Max recommended distance | About 75 feet one-way for 3% drop at 12A |
Kitchen small-appliance circuits must be 20A per NEC 210.52(B). A dedicated circuit for the microwave is recommended but not always required.
12 AWG copper wire on a dedicated 20A, 120V single-pole circuit. NEC requires built-in and over-the-range microwaves to have a dedicated circuit. Countertop microwaves may share a small-appliance circuit (SABC) in the kitchen.
Built-in and over-the-range microwaves effectively need a dedicated 20A circuit: manufacturer instructions require it (enforceable under NEC 110.3(B)), and NEC 210.23(A)(2) limits fastened-in-place equipment to 50% of a shared circuit. Countertop microwaves can use a shared kitchen small-appliance branch circuit (SABC), but a dedicated circuit prevents tripped breakers when the microwave runs with other appliances.
NEC allows countertop microwaves on kitchen small-appliance branch circuits (shared with refrigerators and other small appliances). However, running a microwave and refrigerator simultaneously may trip a 20A breaker. A dedicated circuit for each is recommended.
Most microwaves plug into a standard 120V, 20A outlet (NEMA 5-20R). The outlet should be on a dedicated 20A circuit for built-in models. Over-the-range microwaves may be hardwired or use a recessed outlet inside the cabinet above the unit.