There is normally a label on appliances somewhere because it's a code/standard requirement. The owner's manual for a DCMW11B.F is
here. Manual says "
The electrical requirements are a 120 volt 60 Hz, AC only, 20 amp. ". It also says AC power consumption is 1450 watts. 1450 watts equates to 12.08 amps at 120 volts. If you add a 25% safety factor, this equates to a wire & breaker size of 15.1 amps. Question is, is there a power factor to consider and do they round up to the nearest breaker required above 15.0 amps being 20 amps? I have never been able to find any info. on what the current draw is versus input voltage - does it drop in a linear fashion or? Is there an inrush current that necessitates a 20 amp breaker?
The NEC in itself does not regulate the appliance that is plugged into a general purpose receptacle. For example, the hair dryer we have in the TT is rated 1875 watts but the NEC doesn't require bathroom recepts. to be 20 amps. Interestingly, the MW in our TT is on a 15 amp circuit but it also supplies a recept. at the kitchen counter. Have never had a problem with a toaster & coffee maker on plus the MW (900 watt) at the same time.
Microwave ovens typically aren't on very long, though they can be on occasion. Circuit breakers don't trip the instant current rises above it's rating. They have an inverse time-current characteristic as in the graph below. You can have a small overload on a breaker and it can run for a long time. The higher the current, the sooner it trips. A 15 amp breaker running at 20 amps for ex. would hold for several minutes or longer. A clearer image of the graph is
here.I would say it would be fine on a 15 amp breaker. The worst thing that can happen is the breaker might trip on occasion. Do you know if the MW recept. is definitely on a dedicated circuit? You *could* buy a lo-cost clamp-on ammeter (HF) and see what the MW actually draws.
Should the #14 wire be too small, depending on your FW layout, it may be possible to run new #12 romex cable. I've done lots of wiring in the ceiling space and up & down cabinets in walls including #12 - just takes patience.
