Most home are wired these days with 12/3. Homes 20 years ago or so were wired with 14/3. With a 12 gauge wire you should be good for 2200 Watts. Or the same as a 20 amp circuit. Your smokette is 500 watts so unless you have an unreasonably long extension cord I don't see why 10-20 feet or so would give you that much of a voltage drop. It's always best to stay a close to the outlet as possible but look at it this way,,,,,,,,,the wiring that is in the wall is the same as an extension cord and I would bet it would be no larger that 12 gauge?! I hope this helps,,,I see a lot of stuff on here about extension cords and as long as you stay in the 12 gauge range you should be fine. It's when you get into the 16 gauge that most extension cords are that you could see a drop. Of course to get a 12 you would either have to get a contractor type cord or make your own. Heck,,,make your own. Go to the hardware store and buy a length and then two ends and Wa-La. Custom Cord for the Cookshack....
Hope I helped
Sharing the love,,,,,,,,,,,Iowa Man