Reader Question: numerous over-range microwaves say they call for a committed 20-amp branch circuit, however include a plug the can conveniently be plugged right into a 15-amp receptacle. Is it safe to plug the microwave into a 15 amp circuit? — John

15-Amp vs. 20-Amp Receptacles

John, prior to we answer the concern (which is a good one by the way), let’s testimonial receptacle types. A traditional 15-amp base receptacle is the one many of us are provided to seeing throughout ours house. It has actually two upright slots–one slightly bigger than the other–and a circular grounding slot in ~ the bottom. A 20-amp receptacle, which is much more commonly uncovered in office buildings, looks just like the 15-amp version yet has an extra horizontal slot, do the left slot look prefer a sideways T. (pictures accessible here from wikipedia)

When the microwave says it requires a specialized 20-amp branch circuit, you would mean it to have actually a plug that have the right to only plug into a 20-amp receptacle — a plug v a horizontal tong come fit right into the horizontal slot.

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But the doesn’t. Why?

15-Amp Receptacles top top 20-Amp Branch Circuits

The National electrical Code (called the NEC) specifies the receptacles that deserve to be mounted on miscellaneous levels the branch circuits. For 20-amp circuits (e.g., a circuit defended by a 20-amp breaker), the NEC allows both 15-amp and 20-amp receptacles to be set up on the same circuit.

Even though both receptacle varieties can be mounted on a 20-amp circuit, the circuit wiring will certainly differ. A 15-amp circuit is usually offered by 14 gauge wire, when a 20-amp circuit should be served by12-guage wire. The more thick gauge forced by 20-amp circuits guarantee the wires do not overheat under a 20-amp load.

Why (Some) Microwaves call for a 20-Amp Circuit

Microwaves require a 20-amp branch circuit due to consistent load and also spike issues. Under strenuous use, a microwave could draw nearly the preferably 15 amperes of current regularly for hours. Under this maximum fill scenario, 14- gauge wiring can heat up past safe levels. Also, high strength microwaves have the right to temporarily spike over the 15-ampere limit. If the circuit were governed by a 15-amp breaker, the spike would reason the breaker come trip.

Microwaves include the conventional 15-amp plug due to the fact that these are the plugs many often discovered in dwellings in the U.S. If 20-amp receptacles were common on 20-amp branch circuits in modern-day homes, high power microwaves would most likely sport 20-amp plugs.

How to identify Whether a Circuit Is 15 or 20-amp

The easiest means to recognize whether the circuit is a 15 or 20-amp circuit is to discover the equivalent breaker or fuse in the breaker panel. Note, however, the it is feasible that a former homeowner or electrician made a mistake, for this reason this isn’t 100% reliable.

What’s the Danger?

A microwave plugged into a 15-amp circuit could cause the wires in the wall to overheat and present a fire hazard. An ext likely, however, the microwave will trip the 15-amp breaker and also pose a consistent nuissance.

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Note the you have to never just replace a 15-amp breaker with a 20-amp breaker. This will present a fire hazard since the wiring is no suited because that a 20-amp breaker.

What carry out you think? have actually you installed a microwave v this requirement? walk you operation the different 20-amp circuit?