I have an inspector who says I cannot have a main breaker in a 200A panel mounted in a building addition fed from a 200A breaker in a 320A meter/main. Feeders are 3/0,3/0,3/0,#2 THHN/THWN copper underground in 2" PVC. The second 200A panel is located back-to-back with the meter/main and has a 200A main as well but he says that is okay. He maintains the panel in the addition must be MLO. I cannot find anything in the 2008 NEC to support his position. Any idea where he is getting this idea?
I'd ask HIM cite the particular code article, whether NEC or a local code addition. He cannot just say "no". He's obliged to provide you with this. No need to be rude about it since you are just asking the basis for his decision.
A cop can't pull you over and write you a ticket just because he feels like it either. They must also cite what you did wrong, by referencing the locally adopted code.
Has the '08 code even been adopted in your area yet?
The inspector might be referencing Article 408 Section 408.36 and miss applying it. In a nutshell you need overcurrent protection for a panelboard and the exception says that it's not needed if the feeder has protection sized to protect the panelboard. The '05 code say it's not required but I guess if you have it it's not a violation. the '08 changes it somewhat but the end result is the same.
That's like saying you need 4 receptacles in a wall space and you decide to install 6, that's not a violation.
There is no hazard with having properly sized feeder overcurrent protection feeding a panelboard and having the same size overcurrent device in the panelboard.
Sometimes a panel with a main is cheaper than a MLO.
A main breaker in this application is not required, but certainly not prohibited. In this case, the main breaker is not functioning as OCP, but merely as a local disconnect. It could even be larger than the 200A feeder breaker, and not be an issue.