Has it ever occurred to you that there might be a very good reason why they do not want you doing your own tasks unless you are a "competent contractor"?? There are many local restrictions, such as, "exterior gas lines must be galvanized" (a requirement in this area), which come into play on outside gas lines.
Am I a licensed pro? Nope. I am an M.E. But I've been plumbing for over 20 years, gas and water. No need to explain my background though...this site is here for exactly this reason...isnt it???
Running black pipe is very easy, I am simply making sure I am doing the right thing here. Obviously its not a simple answer to my simple question....OH BUT WAIT...I finally got a hold of someone useful: The lead inspector for my city. And to my surprise the answer IS simple and he was more than willing to answer my question.
No problem running PAINTED black pipe under a deck ATTACHED to the house and ABOVE grade. Were those two points missing, things change and you have to go underground and then come back up to the deck. For this project, its the same as running it inside the home, but the pipe is properly painted.