As late as 25 years ago, there were standards, both NEMA and JIC (Joint Industrial Concil). I still have a copy of it somewhere. It did call for Red as Energized, and Green as Safe, Yellow was Danger. This is a very old standard, and many of you have never heard of it, and can't understand how it got started.
It started with the fact that originally the colors that could be put on lights (and be visible), were limited. Early designers thought as if they were the pedestrian on the sidewalk, waiting to cross (Red = Go, Green = Stop). The early motor control centers used red lights to mean that the contactor was energized. If you find a very old MCC, it may have red lights that come on when the starters are energized. Since red was preempted for energized, that left green to mean "Safe". If you designed according to NEMA standards, you HAD to use these colors. That is why there is so much confusion today.
At some point, the standard-writers realized they were fighting a losing battle, because almost all operators thought as if they were a passenger in a car, not the pedestrian on the sidewalk. If you are the pedestrian, then Green does mean that it is no longer safe to stick your body into the path of the moving equipment, whereas Red means it is safe to proceed.
I wonder if in countries where they still do walk sometimes, if people still think the opposite?
It started with the fact that originally the colors that could be put on lights (and be visible), were limited. Early designers thought as if they were the pedestrian on the sidewalk, waiting to cross (Red = Go, Green = Stop). The early motor control centers used red lights to mean that the contactor was energized. If you find a very old MCC, it may have red lights that come on when the starters are energized. Since red was preempted for energized, that left green to mean "Safe". If you designed according to NEMA standards, you HAD to use these colors. That is why there is so much confusion today.
At some point, the standard-writers realized they were fighting a losing battle, because almost all operators thought as if they were a passenger in a car, not the pedestrian on the sidewalk. If you are the pedestrian, then Green does mean that it is no longer safe to stick your body into the path of the moving equipment, whereas Red means it is safe to proceed.
I wonder if in countries where they still do walk sometimes, if people still think the opposite?