So being "visable" is subject ot physical damage? Maybe if it were subject to vandelism, or traffic.... If he's OK with smurf tube for this, he just might let you slice it down the side and slip it on too.
Electure, you'll love this.... Here in the land of "we wrote our own book", and no its not actually written down in there either. Most commercial services say 600a or more, in say a limited access indoor room is considered subject to physical damage, you'll get the demand for EMT or rigid steel, with "steel threaded or compression fittings". (As die cast or set screw fitting allow un-nessesary impedance in the conductor. All fifteen of them took the same grounding seminar years ago, and no-ones heard the end of it yet.) I have learned to have the book in reach if done other-wise. Sometimes I just do it to avoid the 20 minuite debate about it. As you have said once or twice before its design vs. code, or something to that effect.