WHY?? One leg red in 240AC Circuit

Timeismoney08

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Jul 2012
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So I have always made my 240VAC circuits to include:
1 - Red - 120V
2 - Black - 120V
3 - White - Neutral


According to the NFPA NEC code. It doesn't say anything about the red wire.

Should it just be black, black, white?
 
So I have always made my 240VAC circuits to include:
1 - Red - 120V
2 - Black - 120V
3 - White - Neutral


According to the NFPA NEC code. It doesn't say anything about the red wire.

Should it just be black, black, white?

If one did that, one would always have to mark one black wire. Any industrial electrician would want the Black, White, Red scheme. There are code restrictions on wire color vs. tape. I'm not going to jump up and get my codebook, but I believe that above #4, which would be #2 and up, one can use tape. One is not allowed to tape wires like #12's and #14's etc. for phase identification, one must have the insulation the color they need. They (codebook) are especially picky about neutral and ground colors.
 
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What do the your customer spec’s say? Color coding is not called out in NEC except for neutrals and grounds.

UL & NFPA are not exactly in sync either. UL mentions “line voltage” is black. What if you have 480VAC in your plant but only 120 in your panel. What is line voltage in your panel?

Many industrial plants state black for all 480V, red for all 120VAC, blue for 24VDC+.

I would probably use red for all hot legs of 120VAC in an industrial panel. Then depend on wire numbers for further identification.

For commercial work many USA areas use black/red/blue for 208/120VAC 3 phase and brown, orange, yellowf for 480/277VAC.
 
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What do the your customer spec’s say? Color coding is not called out in NEC except for neutrals and grounds.

UL & NFPA are not exactly in sync either. UL mentions “line voltage” is black. What if you have 480VAC in your plant but only 120 in your panel. What is line voltage in your panel?

Many industrial plants state black for 480V, red for120VAC, blue for 24VDC+.

I would probably use red for all hot legs of 120VAC in an industrial panel. Then depend on wire numbers for further identification.

NFPA 79 - 13.2.4.3
Where color-coding is used for identification of conductor, the following color codes shall be permitted to be used:

(1) Black for ungrounded ac and dc power conductors
(2) Red for ungrounded ac control conductors
(3) Blue for ungrounded DC control conductors



So with that being stated, why would one leg be black and one red in a 240v system? That would indicated that the black is power and red is control...or that the red is not to be used as a power circuit and black not for control.

It doesn't make sense to me. I know the color schemes I'm used to and what is common, I'm just trying to compare it according to code.
 
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.
 
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Hi all you people in the USA, it is funny to me, just about no matter what it is, you have to be different than nearly all the rest of the world, even colours of wires, the rest of the world know that phase colour 240v was red, now can be red or brown, neutral was black can now be black or blue, Earth wire was green but is now green/yellow, just saying, lol
At least your President now knows that COVID-19 isn't fake news and will/is causing havoc in good old USA.
 
Hi all you people in the USA, it is funny to me, just about no matter what it is, you have to be different than nearly all the rest of the world, even colours of wires, the rest of the world know that phase colour 240v was red, now can be red or brown, neutral was black can now be black or blue, Earth wire was green but is now green/yellow, just saying, lol
At least your President now knows that COVID-19 isn't fake news and will/is causing havoc in good old USA.
Well, from our perspective YOU all have it wrong... even in how to spell color!
 
Black = Line Voltage
Red = Control AC Voltage (can be 240, 120, 48 or 24VAC)

If the incoming line power is 120V then I use black for everything powered and after a circuit breaker for the control power I use red.

As far as the line power, if it is 2 or 3 phase I always use black or follow the Brown-Orange-Yellow color scheme SOMETIMES for 3 phase.
 
Im pretty sure the Mayflower didn't leave from America, so maybe the people on the other side of the Atlantic could be right, l also never said you were wrong, even if you do spell colour differently ,ha ha
 
Im pretty sure the Mayflower didn't leave from America, so maybe the people on the other side of the Atlantic could be right, l also never said you were wrong, even if you do spell colour differently ,ha ha

Agree that being different does not necessarily make something wrong. It is now a global economy and these differences are a part of it. The color codes are just one part of it.

Stay safe. 👍
 
Im pretty sure the Mayflower didn't leave from America, so maybe the people on the other side of the Atlantic could be right, l also never said you were wrong, even if you do spell colour differently ,ha ha


Mayflower may not have left from here, but the people it dropped off are the only ones to put a man on the moon! :angr:
 
man on the moon, but unfortunately you may end up showing the world how bad your health care system is compared to the rest of it regarding covid 19.
I hope all people here and else were live to tell the story to another generation about the big scare in 2020, but it looks like there are a lot more fatalities to come yet, even in Australia.
Sorry for derailing the colour of wires, now hopefully back to the topic.
 
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Hi all you people in the USA, it is funny to me, just about no matter what it is, you have to be different than nearly all the rest of the world, even colours of wires, the rest of the world know that phase colour 240v was red, now can be red or brown, neutral was black can now be black or blue, Earth wire was green but is now green/yellow, just saying


AS3000 states that the only explicit requirement is that green/yellow, green or yellow are not used as live conductors and that neutral is either black or light blue. That means that a live conductor can be anything that is not green/yellow, green or yellow, which includes black or light blue. A perfect example is the red/white/blue or brown/black/grey on 3-Phase supplies.


Sorry to hijack your US wiring colour thread - Carry on. 🍻
 
Many countries seem to have their own, however, in the late 70's I worked as an engineer & programmer in the games industry, the machines that came from japan had red, white, green. Cannot remember which was live but the RED was the earth. We had many companies & independents bring in these games because they assumed red was live & green was earth & blew up either the power supply or the board. I know it seems weird that the psu or board would suffer, generally you would expect the fuses but there you go.
 

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