The other confusing part of this experience has to do with generator grounding. After reading various posts about this I thought it was a good idea to have a ground rod even though there is no building involved and all power is from plugs mounted on the generator. When I asked the generator rental company, which is a fairly large supplier with locations in 3 different cities in Oregon, about grounding the generator they said it has never come up before. They don't even have ground rods.
So when there is no building tie in, do the OSHA rules prevail? Those seem to be pretty straight forward in saying that if we are just using cord and plug based loads, the ground/neutral bonded to the generator/trailer frame is sufficient and no ground rod is needed.
If that is true then I won't bother next time with all the hassle of a ground rod.
What OSHA might say could be different then what your AHJ might say, and what they say may or may not be different then what is "actually smart to do."
I've got a 45kW WhisperWatt, and if I bring it up to Seattle, the city requires grounding and an inspection by city L&I. I always ground it in one way or another when working in Seattle; most times I pull the permit but sometimes the client does. (Or, at least... they are telling me that they are... but I never see paperwork around, or have an inspector show up... soooo...)
If you're using a big diesel, and you don't ground, and someone shows up (that AHJ)- they may have the authority to shut down your show until the problem is corrected. Personally, I would rather do it to the most extreme point possible that will ensure that someone doesn't have any standing to drop by and demand that it be shut off!
Same deal about a "large supplier" - I worked with one several times in the Seattle area, and I never saw them grounded. It is possible that, as a part of their contract, they're *just* delivering it to the site, and it is the responsibility of the client to ensure that all legal and safety things are taken care of. But without seeing the rental paperwork... hard to know for sure.
The "big guys" charge a LOT of money for generators, but that's also... permitted... delivered... setup... grounded... inspected... It's a full service package and you are assured (as much as is possible) that there won't be any problems.