Mixing Wire Gauges

Yes, because the microwave has an internal fuse.

Also, the power cord has nothing to do with the branch circuit. You are NOT mixing wire sizes.

Well, you have two positive answers, how about one negative.

Does the manufacturers instructions explain that this unit can be "hardwired" using the cord? I doubt it.

My interpretation of hardwire would be the #12-2 cable connecting to directly to the unit, which may or may not be allowed with your unit.

If you cut the male plug end off the cord, and splice it onto the #12 cable, this will violate the UL listing of the unit, and violate the electric code by including cord into the system.

Cutting off the male plug also eliminates the required service disconnect the plug and outlet offered.

Why do you feel it is necessary to hardwire this unit? You can drill a hole in a cabinet to allow the cord to pass through to where the outlet is located.

Wow. I totally missed the word "hardwire".

TK is completely correct on this.

Never seen a stand alone micro hardwired.

I am also VERY curious (and skeptical) as to why is HAS to be hardwired?

Me Too! Missed the hardwired. Good catch.

Stanfortyman, you are justified in your skepticism: it doesn't HAVE to be hardwired. I am trying to minimize the amount of wall tearing I'll have to do because of a mistake in my initial design. I thought I could get away with not having to drill through the bottom of the cabinet and instead plug into a recessed, wall clock outlet directly behind the mwave. When I got down to business after already having installed said outlet in new construction fashion, I saw that the plug was too long to fit in the recessed outlet and would push the microwave away from the wall. I considered splicing a different style plug onto the cord, but I still had another problem: the cord which exits from the top of the microwave was too thick to route between the unit and the upper cabinets and then down the back of the unit to where the outlet was. I was now considering modifying the microwave so the cord exited from the back. At this point I realized what a big mess I was in just to avoid drilling into my cabinets.

The proper way to fix this (I think) would be to remove the recessed outlet and splice some more romex into that location. Run the romex higher up the wall to a spot behind the cabinet and terminate it at a new 15-amp receptacle which will be accessed through a cutout in the back of the cabinet.

Last night, I didn't quite follow that prescription. I ran the extra romex to behind the cabinet, but I didn't wire in a receptacle -- I was still planning on hardwiring -- but this was before I read everyone's responses here today.

Tkrussel, I don't at all doubt what you're saying, but I just don't understand why the UL Listing and electrical code will be violated if I do this. Can you explain why please?

Thanks everybody

Rather than me try to explain the listing, read this from Underwriters Laboratories to get you started:

UL | Field Modifications

As far as the code issue, hard to show that since what you proposed is not allowed nor addressed in the electric code by any language in so many words that an appliance can be hardwired by cord,

However,
Section 110.3(B) of the NEC states:

Installation and Use
Listed or labeled equipment shall be installed and in accordance with any instructions included in the listing or labeling.

Any AHJ, AKA inspector, will cite this section and have UL behind him to redtag the installation.

What is worse is an inspector hired by your insurance carrier , eh um...., that is knowledgeable about this issue, after any claim has been made.

Also remember there is the service disconnect issue. It's been busy and I am tired, don't make me go find that code too. Hopefully someone can back me up here.

This is an easy catch for any inspector, as many are getting more stringent with UL compliance.

Sure it is a technicality of sorts, but rules are rules,better wording is Standards.

Chances of anything happening is probably slim to none, but that cannot be my official advice. While there is no formal oath electricians take to become one, that I know of, there is professional ethics we volunteer to follow, other than the legal verbage in the state statutes that govern the license we are issued.

Now that I think, I do remember raising my hand while applying for a permit in New Haven, first time I was ever asked. I said "Really?", and he said yep, and every city or town can, and should require an electrician to swear to follow all applicable codes.

So I guess I do recall taking an oath. Anyone else ever run into that?

Do what ever you need to pass the cord through the cabinets to an outlet that can be in any cabinet nearby.

I hope this helped.