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Question about microwaves and dedicated circuits. What's the difference in circuit requirements (amps? dedication? something else?) between microwaves in these locations:

  1. mounted under a cabinet over the range
  2. sitting on a countertop
  3. mounted under a cabinet (but not OTR)
  4. mounted under the countertop (drawer-style)
  5. sitting on a shelf somewhere above the counter
  6. sitting on a shelf somewhere below the counter?
Huesmann
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The code doesn't address microwaves as a specific appliance, but NEC 210.23(A)(2) Utilization Equipment Fastened in Place limits equipment to 50% of a circuit when shared with lighting or other equipment not fastened in place.

So if it's fastened in place, which would likely place it on a designated kitchen circuit, a shared kitchen circuit would have to be 20A, so a microwave would not be able to exceed 1200W without requiring a dedicated circuit.

NoSparksPlease
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    The "fastened in place" seems weird. You could have a microwave on a shelf (not fastened in place) vs. a drawer microwave (fastened in place), but they'd have different requirements. – Huesmann Oct 04 '20 at 21:37
  • Also, you could place your OTR microwave on the counter and it would have different requirements than if you mount it over the range. – Huesmann Oct 04 '20 at 21:42
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    If it isn't fastened in place it is more likely you will replace or move the appliance if it causes tripping, but the code doesn't completely protect you from doing stupid stuff. If it did it would outlaw multiple 15A receptacles on 15A breakers since you can plug in two 1500w heaters. – NoSparksPlease Oct 04 '20 at 23:01
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    An appliance that is fastened in place is guaranteed to be (very specifically) there. An appliance that is not fastened in place may or may not be there at all. And as already noted, it can be moved to another outlet if it's a problem. In the modern kitchen it's a very good idea to exceed code minimum requirements for the sake of not having nuisance trips. Few OTR microwaves are convertable to sit on the counter, as they often have a vent van built into the bottom of them, as well as being relatively wide compared to normal microwaves. – Ecnerwal Oct 05 '20 at 01:11
  • But if you put it on the counter there’s no reason to USE the fan. – Huesmann Oct 05 '20 at 01:44
  • It could be argued that using an OTR on the counter is probably a code violation since the code requires following NRTL listing, listing requires following the instructions, which instruct to mount in place. – NoSparksPlease Oct 05 '20 at 01:51
  • Microwaves which are not fastened in place also have accessible plugs. I have just that here; the microwave is unplugged and I plugged in a toaster and toaster-oven, which I need more. – Harper - Reinstate Monica Oct 05 '20 at 05:42
  • @Harper-ReinstateMonica by "accessible" I assume you mean "uncovered," because I've never seen a microwave without a plug, and the outlet a cord is plugged into by definition must be accessible. Behind a cabinet door is still "accessible." – Huesmann Oct 08 '20 at 10:09