I have been trained that while it is not required by the NEC the following colors should be used for the line conductors in AC systems:
L1 - Black (split phase or 208 three phase)
L2 - Red (split phase or 208 three phase)
L3 - Blue (208 three phase)
480/277 L1 - Brown
480/277 L2 - Orange
480/277 L3 - Yellow
It is my understanding that while this is not NEC required it is "industry standard" and should be followed to provide a higher quality of work with easier serviceability.
Is this truly industry standard that is advisable to follow or is this just a local standard that may differ throughout the country?