The developed countries' electrical code is over designed. But that's good.
I disagree with this. Sometimes if you just meet minimum code it's on the line of poor work. Code just makes sure that for a huge general category of things something is good enough. In many cases it's overkill because of the general nature of code but in many cases I would never do things to minimum code requirements in my house because it's not good enough to not trip breakers, or have enough load for a typical family. They group things together. There is no 11 guage wire or 11.753 guage wire to fit exact needs. Under the most extreme allowed situation for most guage wire you'll see you are bordering failure. All it takes is a slightly loose connection or weak breaker and you start having problems.
[qoute]The voltage drop with 10 Amps for 100' of #12 is 1.5V, for #10 it's .99V. #10 has about 60% more copper in it than #12. There are many more #12 extension cables made. Those two factors drive price. In other words, #10 is a fine cord but #12 will easily meet your spec for current, and it has many uses around the house.
You can calculate it yourself with V=IR. You can look up R for any wire gauge by unit length - search American Wire Gauge.[/quote]
As Gyre said, you're neglecting that initial load, plus with that voltage drop, you pull higher amperage, which increase voltage drop some more. Also how many more amps will his unit draw under your assumed 1.5 voltage drop? Also you're assuming your resistance to match some table which is probably average. That is a dangerous assumption that his cord will match that. You're right that if he takes an ammeter and runs some tests he should be ok. That is probably what I would do if AC were not critical for the Burn. All the theory in the world is nothing compared to actually testing your set-up.