That was a great question. First off, any good electrician will laugh you off the face of the earth if you suggest using anything greater than 12ga. The use of such heavy gauge wire for audio goes against everything they have learned. Hell, it goes against everything I have learned.
Having said that, the heavier the wire, the better the sonics, at least from my experience. I just Google hospital grade electrical outlets and found a number of manufacturers home pages. I found two of two manufacturers who accept 10 ga. I only looked at a couple sites. I use the Wattgate (stupid expensive)after trying most of the high quality outlets. It was a clear improvement, but not until everything else in your system is addressed. This outlet does accept 8 ga. I have tried my Wattgate on a couple other systems and heard very little improvement, so I think your on the right track so fat.
I suggest you research the outlet you want and order it on line. You might talk to Albert Porter, an Audiogon friend who has cryo-treated a number of Hubble outlets and he sells them at cost to us A'gon members. He could tell you the maximum gauge wire they will accept.