I recently helped a friend upgrade his service in a Chicago suburb that follows Chicago code. We failed the inspection because the inspector said that the bonding jumper from the service entrance conduit to the neutral/ground bar was green and the code specifies it "shall not be green or white". Is this true? He suggested black wire with no green tape? Also the GEC to the ground rod was green and he said that was no good but he didn't write it up.
That's just one of the challenges of working in Chicago.
You never know if a requirement is actually in the Code, a specific interpretation, a leftover rule from days gone by, or just that particular Inspector having a better way to skin the cat (or having it out for you).
It would be really nice if they had to give you specific Code references when they make their comments, but that'll never happen.