Timeismoney08
Member
OP
If discussing PLCs and such, we are always discussing industrial applications.
The Black/Red on 240V circuits is applicable to residential wiring. It has no meaning or validity in industrial systems. Black/Red for 240V single phase systems would be confusing and potentially dangerous for industrial systems.
In control panels, black = Line Power, red = AC control power, white = Neutral, blue = DC control power, yellow = Foreign source control power that is not disconnected by the main disconnect. These standards go back to the original JIC (Joint Industrial Council) standards from around WWII that eventually became absorbed by NFPA 79 for industrial machinery electrical systems. The standards were established to help prevent accidents when workers moved between facilities that might have had different standards. So when an industrial electrician opens a panel to try to troubleshoot a problem, he knows what he is looking at without needing a color chart.
So for a 480v fed system that steps down to 240V, you would use Red (120V), Red (120V), White (N)?
I've just never seen it done that way, but that's how I interpret the standards when I read it.