George, you're quite right, the code is 'plain as day.' Alas, it also specifically applies to the entries of tenant spaces (that's the entire sentence before the part you quoted).
So, it seems clear the 'no other load' circuit is only requirede to be provided at the entrance to tenant spaces ... which also suggests that the circuit would be from the tenants' meter.
I just don't see this specific application applying to signs in other locations, signs that might be for the entire building (and thus off the 'house' meter) ... or, for that matter, any requirement that a sign actually use the provided circuit.
Now, if the code panel wanted to say "signs will be powered by dedicated circuits," they could have said so; they were certainly able to do this with the furnace circuit. Instead, all they said, in effect, is that there will be a receptacle by the front door.
Nor does this section distinguish between a temporary sign, and a permanent one. Now, maybe I'm a bit jaded ... but it makes no sense to require a dedicated circuit for a 1/2 amp beer sign over a side window. Naturally, that might also be where the 'show window' issue might arise.
As long as 600.5(A) specifically mentions entryways, location does matter.
While we've passed the submission period for the 2011 code cycle, it's never to early to prepare for 2014. If anyone wants the code to require all signs to be powered by dedicated circuits, they should make the proposal.
