Main Breaker vs MLO

[Lake]

Is there a section in the code that governs when to use a Main Breaker vs MLO? I working on a PV system with a total of 41 string inverters and the output of the inverters being divided between three 600A, MLO, 480Y/277 panel boards. The panel boards are then fed to a 2,000A, MLO Switchboard. I am trying to determine if the 600A panel boards will require a Main or not based on the code.

 

[Little Bill]

Is there a section in the code that governs when to use a Main Breaker vs MLO? I working on a PV system with a total of 41 string inverters and the output of the inverters being divided between three 600A, MLO, 480Y/277 panel boards. The panel boards are then fed to a 2,000A, MLO Switchboard. I am trying to determine if the 600A panel boards will require a Main or not based on the code.

I know very little about solar, but generally if the panel (sub) is in the same building, no main is required.

 

[jaggedben]

You can use which ever you want, as long as you follow the rules in 705.12 regarding ratings of busbars and conductors.

Note that there are a lot of changes in the 2014 code that are very helpful to you. It doesn't sound like MLO vs MB makes a difference in the situation you describe above, although in some situations it might.
See: http://forums.mikeholt.com/showthread.php?t=158930&p=1540635#post1540635

In previous codes, an AHJ can require that the feeder and busbar be rated for 86% of the sum of the utility breaker and all the solar breakers. That's going to make your busbars and feeders much bigger than they really need to be. However, there's nothing in previous codes that unambiguously lets you off the hook if you have a main breaker panel. The AHJ might be generous and recognize that this protects the feeder, and let you reduce the feeder rating. Or they might not.

 

[mwm1752]

690.14( C ) (4) may apply to the DC side