Electrical, Small Appliances

Microwave Breaker Size: Wire & Outlet for Microwave Ovens

When it comes to finding the ideal microwave breaker size and outlet for your kitchen, it is important to consider the size and shape of the appliance, how much power it requires, and what type of circuit breaker and outlet is best suited for safe operation.

Microwaves require either a 15-amp breaker or a 20-amp breaker, depending on the microwave wattage requirements. Microwaves that use 600 to 900 watts can get by with a 15-amp breaker or outlet, but microwaves that use over 900 watts or higher should have a 20-amp breaker or outlet for microwave ovens.

The National Electrical Code (NEC) requires a 120-volt 20-amp breaker, 12 gauge wire, and 20-amp outlet in new construction homes. This ensures you are safe from circuit breaker tripping, regardless of your microwave size.

Even though a 15-amp microwave breaker size is usually enough to power smaller microwaves, you should stay on the safe side and always install a 20-amp breaker. Installing a 20-amp microwave breaker size has become the new norm in electrical work because there’s nothing wrong with installing a breaker that’s too big, but you’ll have big problems installing one too small. 

Microwave Breaker Size

What Size Breaker for a Microwave

When determining what size breaker do I need for a microwave, it’s important to consult the manufacturer’s instructions. Generally, electric microwaves require a dedicated 20-amp circuit with a 12/2 gauge wire. You will need to install a 20-amp single pole dedicated microwave circuit breaker size with a 20-amp electrical outlet.

Even though some microwaves only require a 15-amp microwave breaker size to power them, installing a dedicated 20-amp breaker is common practice. Installing a breaker slightly larger than you need will ensure that a power surge doesn’t trip the breaker or damage your microwave. It will also make it so that you can power your microwave simultaneously with other devices in your home and kitchen. 

The correct wire size running to your microwave is essential to having the right microwave breaker size. For both 15 and 20-amp circuits, you should have a 12/2 gauge NM wire running from the breaker to the outlet powering your microwave. Be sure the outlet can handle a 20-amp circuit and has a spot to attach the ground wire. 

What Size Outlet for Microwave Ovens

The size outlet for microwave ovens is typically a three-pronged 120-volt 15 or 20-amp receptacle. The voltage of the receptacle should match the voltage rating of the breaker and the microwave oven’s label.

A dedicated circuit with an appropriate breaker and wiring should be used for microwave ovens to ensure they are properly protected.

What Microwave Wire Size You Need

The type and size of wire needed to power a microwave depending on the wattage rating of the appliance. M

Microwaves with a wattage rating of up to 1000 watts require a 14-gauge wire for a 15-amp breaker or a 12-gauge copper wire for a 20-amp breaker.

Most new homes will have a 20-amp receptacle with a 12-gauge wire on a 20-amp breaker size for microwave.

Different Microwaves and Their Power Requirements

Saying that all microwaves need a dedicated 20-amp circuit and 12/2 NM wire might seem slightly cut and dry. Can’t you just plug your microwave into whatever outlet is nearby? Sometimes you can, and sometimes you can’t. The size and type of your microwave will determine its breaker and wire requirements. 

500 to 800-Volt Microwaves 

Most modern kitchens have microwaves with dedicated circuits and a specific outlet. Dedicated circuits usually apply to larger microwaves installed in a specific and permanent location. However, you don’t need a dedicated circuit or breaker for smaller microwaves that use 500 to 800 electricity. 

Microwaves of this size usually sit on countertops or kitchen tops, and you can plug them into wherever is convenient. As long as it’s plugged in in your kitchen, you can rest assured that the wire and breaker powering are large enough. 

800 to 1,200-Volts Microwaves 

800 to 1,200-volt microwaves are a little tougher to peg as far as wire and breaker size. To be safe, you should have a dedicated circuit running to the microwave with a 12/2 wire and a 20-amp breaker. However, you can usually get by with a 15-amp breaker if necessary. 

1,200+ Volt Microwaves 

For 1,200 volts or larger microwaves, you should have a 20-amp breaker with a dedicated circuit. These microwaves are usually mounted in permanent locations, above your stove, under a cabinet, or somewhere else in your kitchen. Some microwaves of this size are also hard-wired and bypass the need for an outlet. 

At any rate, 1,200 volts or larger microwaves need a dedicated 20-amp circuit and a 12/2 NM wire. Check your manufacturer’s manual because some microwaves require a 30-amp breaker.

Why do Microwaves Need Their Own Circuit? 

Technically, microwaves don’t always need their own circuit, especially in older homes. Running a dedicated circuit wastes breaker box space if you have a smaller microwave that uses less than 600 watts. When your microwave needs its own circuit, you have one that uses upwards of 1,200 or 1,500 watts of electricity. 

You need a dedicated circuit because you won’t be able to power anything else on the same circuit as the microwave while it’s running. Your microwave will consume too much power and could cause your breaker to trip. 

I know firsthand the struggles of operating a microwave on a circuit that’s too small to handle. You’re constantly running back and forth from your kitchen to your basement to reset a tripped breaker, hoping you don’t overload your electrical system and ruin something. 

Risks of Installing a Breaker That’s Too Small 

Thanks to advancements in the practices and components used in electrical work, the risks of a breaker or wire being too small aren’t as bad as they once were. In older houses with outdated electricity, you ran the risk of having your electrical wire overheating and starting a fire if your breaker or wire weren’t the right size. 

Nowadays, however, the biggest risk of installing a breaker or wire that’s too small to power your microwave has the breaker trip. A tripped breaker is an inconvenience, but it’s also a safeguard against the alternative, which is an overheated wire. 

Don’t Forget About the Wire

It’s equally important to have the correct size wire powering your microwave outlet. In modern kitchens, 12/2 NM wire has become the standard. It’s the perfect size in that it will never be too big or too small to power a microwave. A wire of this size will also ensure that it will not get overworked and run the risk of overheating. 

Microwave Breaker Size FAQs

The microwave breaker size, wire, and outlet all play a role in safe microwave operation. When looking for the microwave breaker size, you may have other questions. Here are some frequently asked questions for microwave breaker, wire, and outlet sizes.

Are microwaves 20 amp?

No, microwaves are typically rated for 10 amps or less. The average microwave oven consumes a whopping 1000 watts of electricity, the equivalent of 8.3 amps when plugged into a 120-volt outlet! This amount of current is enough to power even the most powerful microwaves on the market.

What size breaker do I need for a 1000 watt microwave?

You will need a 15-amp or 20-amp circuit microwave breaker size for a 1000-watt microwave.

Does a 900-watt microwave need a dedicated circuit?

Yes, a 900-watt microwave should have its own dedicated circuit. A dedicated 20-amp microwave breaker size helps prevent it from tripping the breaker with other high-wattage appliances like an oven or dishwasher that may be on the same power circuit.

How many amps does a 1200-watt microwave pull?

A 1200-watt microwave will draw 10 amps of power. While some microwaves only require a 10 or 15-amp circuit, it’s always best to stay on the safe side and install a 20-amp circuit. 

Do microwaves need a 20-amp outlet? 

Modern outlets are capable of handling 15 or 20-amp circuits equally well. 

Final Thoughts 

Microwaves are handy kitchen appliances that use more power than you would expect based on their compact size. Therefore, you must have the right microwave breaker size and wire powering it. If you’re unsure what your microwave’s voltage and amp requirements are, you should stay on the safe side and run it on a 20-amp circuit. 


Hubert Miles | Licensed Home Inspector, CMI, CPI

Hubert Miles is a licensed home inspector (RBI# 2556) with more than two decades of experience in inspection and construction. Since 2008, he has been serving South Carolina through his company, Patriot Home Inspections LLC. As a Certified Master Inspector, Hubert is dedicated to providing his expertise in home inspections, repairs, maintenance, and DIY projects.