Does a Microwave Need a Dedicated Circuit

Microwaves are a staple appliance for any modern kitchen, so which outlet should you use to ensure that yours works?

The type of circuit needed for a microwave depends on its wattage requirement. Smaller countertop microwaves can be connected to ordinary branch circuits. Meanwhile, larger ones, such as microwave ovens, need dedicated circuits. Microwave models have different wattage requirements, so refer to the device’s voltage and amp rating when selecting a circuit. 

I will show you some charts based on wattage and give recommendations below.

What Types of Microwave Need a Dedicated Circuit

Ultimately, the microwave’s wattage requirement determines whether you need a dedicated circuit. 

Electrical appliances rated 1,000 watts or above should be connected to a dedicated circuit. Microwave ovens are usually classified as energy-demanding appliances, so you’ll need a dedicated circuit to avoid voltage drops. On the other hand, countertop microwaves and other smaller models have smaller wattage requirements. They can be connected to shared circuits without compromising the circuit and other connected appliances. 

The wattage requirement is usually based on the size of the microwave. 

  • Compact Microwaves: 500 to 800 watts
  • Medium-sized Microwaves: 800 to 1800 watts
  • Large-sized Microwaves: 1200 to 1200 watts

You can check your microwave model’s voltage and amp rating to determine the exact watts needed. If you cannot find it and are unsure which category your microwave falls under, it’s best to err on caution and opt for a dedicated microwave circuit. 

Does the National Electrical Code Require Dedicated Circuits for Microwaves?

The National Electrical Code doesn’t specifically require using dedicated circuits for microwaves. Instead, the regulations for microwaves fall under the general regulations for home appliances. 

The first regulation is that if you’re connecting the microwave to a branch circuit (a circuit shared by multiple appliances), it should not exceed 80 percent of that circuit’s power rating.

A single appliance shouldn’t overwhelm a branch circuit since this can trigger the amp circuit breaker. For example, if your amps circuit rating is 30 amps, then a lone connected appliance should only use 24 amps or less. 

The second regulation is that the amp rating of a fixed or fastened appliance should be half or less of that of the branch circuit.

This rule would apply to larger microwaves like an oven microwave model. For example, a 24 amps microwave should only be connected to a 48 amps or higher branch circuit. 

These guidelines must be followed to ensure the electrical system’s safety for the homeowner and the entire community. Homeowners, in particular, must adhere to the National Electrical Code so that their property follows the minimum safety standard. 

Factors to Consider for Your Microwave’s Circuit

While the National Electrical Code is pretty clear on what microwaves you can connect to a branch circuit, most people have trouble following the second regulation. 

It can be difficult to ensure that powerful microwaves stay within the tolerable amp rating when connected to a branch circuit. 

Branch circuits usually power at least two appliances, so it’s difficult to power larger microwaves without the circuit breaker tripping. For those situations, the best alternative is to use a dedicated microwave circuit instead. Dedicated circuits have amp breakers – devices that act as a failsafe when voltage drops or overloading occurs – making them safer to use than branch circuits. 

You can opt to make branch circuits safer by adding GFCI outlets to them. 

A GFCI (Ground-Fault Circuit Interrupter) acts as another layer of protection against abnormal electricity flow. It looks like an electrical outlet with additional buttons usually placed between the sockets. Those buttons are actually for the built-in trip inside the outlet. This trip differs from the one found within your circuit box, so other outlets connected to the same circuit will not be affected.

It’s best to use a GFCI outlet if you’re planning to use a branch circuit for microwave ovens and other microwaves that use a lot of wattages. Branch circuits may be connected to multiple outlets, so accidentally overloading an outlet will cause problems for all other connected outlets. GFCI prevents this problem from occurring by grounding the problematic outlet immediately.

We established that dedicated circuits are generally safer than branch circuits, but most households only have a few dedicated circuits. Consider adding electrical circuits to your household if all your dedicated circuits are in use. 

One of the most important things to consider is the amp breaker capacity if you’re adding a new dedicated circuit. 

The amp breaker must be able to support the wattage requirement of your microwave. The breaker size shouldn’t be too large as the breaker may not trip if any voltage drops or overloading occurs. Conversely, breakers that are too small will often mistakenly trip, even if the voltage usage of the microwave is within tolerable levels. 

In general, the proper amp breaker size for dedicated circuit microwaves is as follows:

  • Below 600 Watts Microwaves: 15 Amps Circuit Breakers
  • 600 to 1000 Watts Microwaves: 20 Amps Circuit Breakers
  • Above 1000 Watts Microwaves: 30 Amps Circuit Breakers

Video References

America’s Test Kitchen

The Gadget Show

House Dr tutorial

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About Sam Orlovsky

b1d87d2ee85af3e51479df87928bdc88?s=90&d=mm&r=gCertifications: B.E.E.
Education: University Of Denver - Electric Engineering
Lives In: Denver Colorado

Electrical engineering is my passion, and I’ve been in the industry for over 20 years. This gives me a unique ability to give you expert home improvement and DIY recommendations. I’m not only an electrician, but I also like machinery and anything to do with carpentry. One of my career paths started as a general handyman, so I also have a lot of experience with home improvement I love to share.

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