Microwaves of all types require a lot of power even compared to other kitchen appliances- often more than some circuit breakers are capable of safely providing, so knowing what size breaker for a microwave to use is an essential part of safely operating it.
The best microwaves will be wired properly for safe use even without a dedicated circuit, but understanding the power requirements of kitchen appliances will allow you to make sure you never run into potentially dangerous electrical issues. Understanding the electrical needs will also help you better understand common microwave issues, such as why sometimes microwave ovens heat unevenly.
If possible, it’s best practice to use a 20 Amp circuit even for a low-wattage microwave oven and to use a dedicated circuit.
Kitchen appliances often have a high power requirement, and sometimes more than can be provided by a single standard home circuit breaker if it’s shared with other appliances or lights in the home.
Microwave ovens- especially large over-the-range microwave ovens– have higher power requirements than most, and because of that, electrical issues result in dimming house lights or blown fuses that can occur more often than it does in other appliances. That’s why plugging your microwave into its own dedicated electrical circuit (a separate circuit) so that it’s not sharing power load with house lights or other appliances is important.
However, it’s also important to know what size circuit breaker your microwave requires. For the most part, your home will already have the appropriate size, but it’s a good idea to know for sure, and if you’re doing renovations or building a new home, the appliances you’re going to be using is an important thing to plan for.
Most microwaves require a dedicated 20-amp 120/125-volt circuit with a time-delay fuse to feed it power, using a 12/2 NM grounded wire. These are often standard in homes, but you may wish to consult either your utility company or breaker box for this information to confirm- though the latter may not always be possible. It’s also a good idea to know what to do when the microwave blows a fuse when it starts.
Some larger, built-in microwave ovens, including many over-the-range microwaves and microhood combination microwave ovens, can draw as much as 1700 watts of power. Making sure you have the appropriate microwave oven circuit and that the microwave has its own dedicated outlet and circuit (and not, as happens often, one shared with a refrigerator) is even more crucial for safe operation without the risk of dimming lights, blown fuses, brown-outs, or other electrical issues.
Additionally, many building codes dictate specific rules for kitchen circuits and standard appliance outlets- these are sometimes even shown on a breaker’s panel. Consultation with or advice from a licensed electrician to be sure you’re in compliance with local electrical code is strongly advised here.
Though it’s common to see microwaves, including high-wattage over-the-range microwaves, on 15 Amp circuits, they should always use 20 Amp circuits or they can’t be considered safe to use.
Is a 15-Amp breaker big enough for an 1100-watt microwave?
Though it’s not uncommon to see large microwaves (especially over-the-range models) using a 15 amp circuit breaker, any microwave oven this large should absolutely use a dedicated 20 amp breaker or 20A circuit for optimal safe use.
What size breaker do I need for a 1000-watt microwave?
A 1000-watt microwave oven draws around a 1700-watt of wall power rating, which is around 14 amps, however, even smaller 700-watt microwaves should ideally use a dedicated 20 Amp circuit for optimal safe use, and this goes doubly for larger 1000+ watt models.
Do microwaves absolutely need a 20 Amp circuit or is it merely best practice?
While it’s common for many users to plug their microwave into a 15 Amp circuit, it can’t be considered 100% safe or risk-free, even if it’s a low-wattage 600 or 700-watt model. For 1000+ watt models, it’s not just a bad idea, it’s a must.
STAT: Most circuit breakers will not trip until they’ve hit 20% over the maximum power they’re rated for. (source)