Actually it's not "supposed" to be anything. Just a trade practice.
Right, and if there is one voltage system on a premises you can take that even further and not identify any ungrounded conductors at all if you wish, high leg being exception for those systems that have one. And that has been somewhat my practice over the years. If I run multiple three phase motors through same raceway, I generally ran three black wires for motor 1, three red wires for motor 2, three red wires for motor 3.... I generally did not care about rotation - most of what I have worked on it is not that critical that we can't "bump" it to check rotation when near completion and simply reverse a couple leads at the controller if rotation is wrong, actually takes less time then using ID methods and you still have a 50-50 chance of it being right. I may still do this practice if multiple voltages are present, and use ID tape to identify the required ID of voltage and phase, or the other way is to still go with three colors of insulation and use ID tape or other methods to isolate each individual circuit. If you get in a pinch and don't have the right color of wire it can really mess up your identification methods though, yet in most circumstances anyone that is qualified to work on it probably has little trouble figuring out what is there should you have one motor in the place that has three black conductors supplying it with orange, yellow and brown tape identifying each conductor instead of orange, yellow and brown conductor insulation:roll:
Next thing you know he will be telling everyone about the secret handshake.
OOPS.....
hmy:
Now we're going to have to change it
