Where in the code does it explain about using main lug panels. I'm going about 220ft. from a main breaker panel, feeding a 100 amp panel. Normally I would use a main breaker panel anyway, but so far I don't seem to find one that fits my need.
thanks

I don't think it does.
I always like using a panel with a Main because it reduces the temptation to work it hot when someone doesn't want to walk to the feeder breaker and turn it off...but I don't think there's a requirement for a main.

A main is only required if it is in another building and they do not use the 225.32 ex1 excuse "documented safe switching procedures".

When they are not within sight, I am not really happy but it is legal. Good documentation of where the feeder breaker is should be on the MLO.

Greg:
I agree with you.

How do you feel IF the sub has only 4 single pole branches?

Think the old six switch rule!

That does not really address the hot bus but I suppose there are still hot components in a panel with a main. (Unless you are in Canada where they have a cover over the main lugs from what I understand)

Greg:

IMHO, the 'six switch rule' was OK back when there were limited circuits compared to today.

On the commercial side, the $$$ saved by eliminating the main, catches up when the buildings are renovated. Quite a few show up each year.

I understand that it is not a huge hazard. I suppose I was just saying identifying where it comes from is a good idea for that time when you are working on something more complicated than a branch circuit.