Not meaning to literally jump in-between you and Mike, however it comes down to this exact phrase that makes the dollar and the world go round;
#1)_"local authority having jurisdiction"_
...and to cover all other litigation;
#2)_"Installed according to manufacturers Instructions"_
This is what is talked about amongst the Polo shirts in the SUVs, while the blue shirts in the pick-ups and vans talk about any/all codes, pussy and the best practices to install something. Not in all cases though. The experienced blue shirts understand the SUV talk as the years go along, but most do not, but that's OK. It still results in very good field work.
Then, when the time is right (learned the above #1 & #2) you'll have a blue shirt become a very qualified job foreman, who knows the right way to install the job AND complete the job within budget and not have to do the job over. Oh, the polo shirts like to hang around the blue shirts for a few minutes every day to talk about pussy and old job war stories.
Add or correct as needed, still on firs cup of coffee. 8-)
-zero