I had a contractor install a 3 phase panel for a single phase system.

He installed a 2-pole breaker which landed on bus B and C and then installed a wire from one terminal of the breaker to the other which in essence made phase C in the panel phase B. The phase arrangement was then A, B, B, A, B, B, etc.

He then proceeded to fill most of the breaker spots with 1-pole breakers but some had 2 pole. He did make sure to put the 2-pole breakers where he landed on both legs of the single phase service.

I see nothing in the code that specifically disallows a 3 phase panel on a single phase service, but since he could not show me which neutrals went with which hots (not to mention this is the most unorthodox installation I've ever seen) I told him to install a single-phase panel.

Any input on code violations on this type of installation would be helpful.

I do know about 110.3 but what does "considerations such as the following shall be evaluated" mean exactly?