Ok, it all does.
Is it fluorescent or incandescent or LED or neon? See what 600 says about ballasts and drivers and neon, whichever applies.
Are there separate branch circuits from each merchant so they control their own sign or just one for the whole thing? See what 600 says about disconnects.
You may have trouble navigating the NEC but now that you have been given the applicable article you are going to have to read through it to find what applies to your situation. It's not that long.
-Hal