Can a microwave be on a shared circuit?

Don’t put your microwave on a shared circuit, especially one that’s shared with other appliances. You are better off running a dedicated line and circuit breaker for this one.

The microwaves require a 120 volt, individual, properly grounded branch circuit with a 3 prong grounding type receptacle protected by a 15 or 20 amp circuit breaker or time-delay fuse.

A 1000 watt microwave requires about 1700 watt of wall power. That would be 14 Amps.

To determine what gauge wire you need, consider the carrying capacity and the amount of current the wire needs to conduct (measured in amperage or amps). Wire gauge is directly related to how many amps you need to run through it. The distance you need the wire to go can also impact the gauge of wire you need.

Microwave ovens often demand dedicated circuitry, but this isn’t always a necessity. The National Electrical Code requires it for all fixed equipment, so a circuit must be set aside for any built-in oven. Small or older countertop models draw less power than modern full-size units.

General purpose lighting and/or outlets can be wired with 12-2 Type-NM cable placed on a 20 amp circuit breaker, or 14-2 Type-NM cable placed on a 15 amp circuit breaker.

Regardless of what size breaker you use, you should always power your microwave with a 12/2 gauge wire. Even though a 15-amp breaker is usually enough to power smaller microwaves, you should stay on the safe side and always install a 20-amp breaker.

How is it safe? A dead short in the #14 branch will draw up to 30 amps of current through the #14 wire. @Bryce: A dead short on the #14 branch would pass a lot more than 30 amps, but would only have to do so long enough to trip the breaker.

Microwaves require a 20-amp branch circuit due to constant load and spike issues. Under strenuous use, a microwave could draw nearly the maximum 15 amperes of current regularly for hours. Under this maximum load scenario, 14- gauge wiring could heat up beyond safe levels.

According to the 2020 version of the NEC, you can’t power a microwave and refrigerator on the same circuit because each of these appliances requires a dedicated circuit, which is one shared by no other appliances or lights.

12-gauge are used in kitchen, bathroom, outdoor receptacles, and 120-volt air conditioners supporting 20 amps. 10-gauge are used in electric clothes dryers, 240-volt window air conditioners, electric water heaters supporting 30 amps.

With 12 gauge, you need to use the screw terminals. You can use 15 amp outlets on either 15 or 20 amp circuits. 12 gauge wire is the minimum for 20 amp circuits. 14 gauge wire is the minimum for 15 amp circuits.

Microwave ovens often demand dedicated circuitry, but this isn’t always a necessity. The National Electrical Code requires it for all fixed equipment, so a circuit must be set aside for any built-in oven. Small or older countertop models draw less power than modern full-size units.

The microwave oven needs a dedicated 20-amp, the 120/125-volt circuit to feed it. This will require 12/2 NM wire with a ground. Microwave ovens come in different varieties and sizes.

12-gauge wire is the minimum requirement for outlets on a 20-amp circuit. 12-gauge wire can be used for outlets on both 15 and 20-amp circuits. 14-gauge wire is unsafe to use for outlets on a 20-amp circuit. 14-gauge wire can only be used for outlets on a 15-amp circuit.