Circuit requirements for undercabinet microwave

Doing some kitchen reno work recently in a family members condo. I ran all of the new electric lines, which called for 2 new countertop circuits as required by code. The plans originally called for a microwave to sit on the countertop. Now plans have changed, and the microwave is now being mounted under a cabinet. I'm not sure but I think I read somewhere that if the microwave is being mounted under a cabinet, it needs its own circuit, which is a problem now since all the wall are closed up and I can't run a new line. However, I can run a new line from one of the countertop outlets up about 3 feet to the cabinet. So my question does anyone know what the requirements are?
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On 6/1/2011 9:04 AM, Mikepier wrote:

Can you run a new circuit via the attic? Common sense and best wiring practice calls for a separate 20amp circuit for the larger built in microwave ovens but with all the new current hungry counter top items being used these days, you will wind up with the problem we have at my home where we trip the circuit breakers to the kitchen all the time because of all the modern kitchen counter top conveniences. ^_^
TDD
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wrote:

No, this is a condo Bldg, no attic. I don't understand the code. If it is sitting on a counter, perfectly fine to plug it in an outlet. Also, I think if I attached it to a cabinet, but draped the cord down and plugged it in the counter outlet, thats fine too, no new circuit needed. But once you attach it to a cabinet, it needs its own circuit. Does not make sense. Electrically, its using the same current.
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Built in microwaves generally are higher wattage and thus the seperate 20 amp circuit requirement.
You have a choice
go back to a countertop microwave
Do the job right and run a new 20 amp circuit with 12 gauge wire.
or hack a work around and live with tripped breakers when someone forgets you cant use microwave while using any other countertop appliance.:(
Personally even a day of work is better than a lifetime of inconvenience:(
In preping for a kitchen remodel in a 60 year old home I added a bunch of new circuits dead ended in work boxes on basement cieling, to make later kitchen job easier
There are special long bits for electrical work they are 3 feet long and extensions are available you can drill directly from hole in wall behind new microwave to basement, just use care watch for obstructions like water lines and other power lines, a small mirror in hole helps
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On 6/1/2011 10:16 AM, Mikepier wrote:

I don't think there is any requirement.
--
bud--


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The counter top ones usually don't come in as high a wattage as the under the cabinet ones. But you can control that by selecting a reasonable one.
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On 6/1/2011 10:16 AM, Mikepier wrote:

You didn't mention a wattage for the microwave or current requirements.
TDD
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wrote:

I ran a new line for mine, but it is not true that larger microwaves need more power. In my case, my combo turbo/microwave over stove, under cabinet uses less than my little physical sized table top unit. Just read the watts. They usually recommend a separate line regardless. Is nice to be able to use appliances without thought of tripping breakers.
Greg
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You pay the code experts in City Hall to know this. Seems to me they are supposed to answer questions like this as part of their job. Most of the local ones here are very helpful so you may have similar competent people in your area. Give it a try.
Joe
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*Article 210.52 covers this. You can use one of the countertop 20 amp circuits to feed the receptacle for the microwave above the countertop.
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** You may actually create a situation if you mount the microwave to a wall cabinet, above the countertop, and it blocks one of the required counter outlets. If you do this, technically that counter outlet no longer qualifies as one of the required ones. The same thing applies to counter mounted garages. (nec 210.52 (5) but in my opinion, you'd be splitting hairs
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