ON/OFF color
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I don't know IEC, but I know ANSI says that green is a "safe" or "normal" condition and red is a "dangerous" or "fault" condition.
There doesn't seem to be a consensus on this. I always wired my panels to NFPA 79, but I have seen a whole mess of different color schemes, and a lot of them also follow traffic light colors: "Red" is stopped and safe, "green" is running and dangerous.
There doesn't seem to be a consensus on this. I always wired my panels to NFPA 79, but I have seen a whole mess of different color schemes, and a lot of them also follow traffic light colors: "Red" is stopped and safe, "green" is running and dangerous.
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That is how I looked at it but many MCCs are wired green for stopped motor and red for running motor.
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nearly all electric household items i have seen have a red lamp that indicates that the device is running/ON
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Not here. In the utility here, red is closed, green is open. All our mimic boards have this.
Can anyone tell what's happening here?? OOPS!
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There's a difference here between mimic lights and control stations. I'd have to look at the colours for the control buttons on the MCC's. I have a feeling they are green go red stop. I'd have to confirm though.
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There are standards. NFPA 79 is an ANSI standard, and it lists the colors I mentioned above. Here:
But even that's ambiguous. Is a normally functioning contactor "dangerous" just because it's closed? If not, why make it red? "On" and "Off" are both "normal" conditions, so do you have 2 green lights?
Everyone seems to have their own interpretation.
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I have seen the same for MCCs, but all of the switchgear I have seen is the opposite.
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ANSI standard C-37 for power switchgear, which is what also comprises UL-1558, specifically calls for Red to to indicate that a breaker is Closed, energized, whether it is a pilot light or a machanical flag. That is not negotiable or interpretable, but one does not absolutely need to use ANSI compliant / UL listed gear. So it is safe to say that anything that uses a different color scheme would either not be designed to ANSI standards, or it was altered after the fact by or under the direction of someone who should not have been doing so.
In addition, when it comes to CONTROL systems the old standard, to which most industrial electricians were trained for years, was called JIC, the Joint Industrial Council. It SPECIFICALLY called for Red to be running/on/energized, green to be ready/off/electrically safe (de-energized). The JIC standards fell by the wayside years ago unfortunately, but are what became NFPA 79 for machinery control systems. There is no national law enforcing NFPA 79 as a standard, but local AHJs can opt to do so. The prudent designer of OEM equipment and control gear that is sold nationally, such as MCCs, then would use that standard to avoid the possibility of getting rejected by a local AHJ, hence the way you see most MCC standard drawings depicting the "Run" light as Red. But that does not mean that some company can hire an Engineer that has squat for experience and uses the "Traffic Light" scheme, so once it becomes a company standard, an Electrician working for that company must follow that standard.
Doesn't make it right though... :whistling2:
In addition, when it comes to CONTROL systems the old standard, to which most industrial electricians were trained for years, was called JIC, the Joint Industrial Council. It SPECIFICALLY called for Red to be running/on/energized, green to be ready/off/electrically safe (de-energized). The JIC standards fell by the wayside years ago unfortunately, but are what became NFPA 79 for machinery control systems. There is no national law enforcing NFPA 79 as a standard, but local AHJs can opt to do so. The prudent designer of OEM equipment and control gear that is sold nationally, such as MCCs, then would use that standard to avoid the possibility of getting rejected by a local AHJ, hence the way you see most MCC standard drawings depicting the "Run" light as Red. But that does not mean that some company can hire an Engineer that has squat for experience and uses the "Traffic Light" scheme, so once it becomes a company standard, an Electrician working for that company must follow that standard.
Doesn't make it right though... :whistling2:
Looks like the transformers connecting the 2 voltage systems are de-energized and being serviced? Feeders are feeding through the busses however. HVDC in the upper part?
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RED = BAD, GREEN = GOOD.
If something is "on" and this is good or preferred
all depends on the situation at the time.
For some people it could mean the opposite
All depends on the application and the sysytem using it !
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