This was another of the great struggles between Edison and Tesla, with Edison prevailing after he held Tesla's dog hostage and threatened to electrocute her using a Tesla ac generator.
The victory proved somewhat shallow when it was later revealed that Edison was color-blind.
yes, the red=unsafe, green=safe (usually) approach also extends to valves that are usually labeled similarly (green = closed, red = open).
And of course open for a valve is like closed for a breaker, and open for a breaker is like closed for a valve. So naturally the color for an open valve is opposite the color for an open breaker. The linguistically similar positions must have color-coded oposite positions because the functionally similar positions have the same color and their linguistically similar positions have opposite colors. The color relationship is opposite the linguistic relationship because the linguistic relationship is oppostie to the functional relationship. But at least their color relationship is in accordance with their functional relationship.
time for that beer now...
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In our plant, red is close and green is open for breakers. Its American standard i think coz the panel is made in US. But to my surprise in the SCADA green is close and red is open for breakers and even motors. ie when the motor is running its color is green when off its red. When i trace where the software comes from its from Australia, hehe. But of course the programmer can want any color or might reverse that color coding if wanted. What i just want to express is I think the color preferences differs from one standard to another. In our case we have mixed standards, lolz. But its just easy to rectify it, just exchange the indicating buld covers to coincide with the SCADA, lolz!!
I think that goes back to the days of Adam and Eve. As long as the apple (yes, I know, it probably was a durian, but that does not fit), as I said, as long as the apple was green, it was OK to eat. It was only when it got red that they were told not to eat it. A little late, perhaps, but still. So, God (not Edison, not Tesla, not even Steinmetz) decided that.
I believe it was actually the U.S. Navy. In all Naval configurations you will always see Red=running (unsafe) and Green=stopped (safe) and since power plants adapt most Navy S.O.P.'s you find it common in most power plants.
I've had consulting engineers INSIST that all lights should be green under normal conditions. So on normally open breakers, green=open, and on normally closed breakers green=closed! Talk about confusing!
The indicating lighting light standard has been around USA since the before the forties, I have a copy of the old Electrical Machine Standards that shows it that way. Its a bad standard because it causes a lot of confusion. Since it conflicts with traffic signal logic- red is stop and green is go.
The only standard I have seen that has it right is mil standards. Yes,it is dangerous, because a lot of people will not comply with the standard it is all mixed up. Maybe the internation standards can correct this problem.
I don't know why some people are resistant to changing this, my guess it is people that do not like changes period.
I like the traffic light analogy too: you cross the intersection when it is clear, and a breaker indicator is green when it is has cleared.
As for the origination, don't know, but it's been almost always been around power plants as far as I can tell. Looking at my antique book library (Audel's New Electric Library, 1st Print 1931), volume VI has a chapter about substations, and an example used was a General Electric Supervisory Controller for dispatch stations (the birth of SCADA?) The front of this supervisory controller was full of indicator lights for each station switch position: red=closed, green=open, white=Automatic (tripping) operation, and amber for synchronzing local & remote circuit-selection relays that coordinated alignment for opening/closing desired circuit.