24VAC Color wire by NEC
- Thread starter mav01
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dcspector
Senior Member
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- Burke, Virginia
I do not think the NEC covers color coding except for 200.7(B)
dcspector
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- Burke, Virginia
S'mise said:
Good find.....
John Valdes
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- SC.
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- Retired Electrician
Color is not as important as correct marking or numbering. If you have a print use the numbers used on the diagram and place little concern on color. But be consistant with the color you choose. Do not sway from the color in jboxes or anywhere the color could be changed. A good example would be a control panel with every wire the same color. Its the marking, not the color that is required for identification. I always just pick a color I like...LOL
I think Yello would be perfect!!!!!!!!!!!
I think Yello would be perfect!!!!!!!!!!!
Intrinsically safe not for 24v air valve
Intrinsically safe not for 24v air valve
It depends what the application is. The question asked was about NEC specified colors. But I have a hunch you are dealing with a machine tool control panel circuit that would fall under NFPA79 rules. Thats a different animal. If wire is Yellow it means a source derived from another location and is only yellow outside of it's place of origin. The color for low voltage DC is blue, and blue with white for grounded DC.(common)
Color is very important, someone could get killed thinking the power is completely locked out and touch a live wire that was supposed to be marked yellow! Find out what rules apply for your situation.
Intrinsically safe not for 24v air valve
It depends what the application is. The question asked was about NEC specified colors. But I have a hunch you are dealing with a machine tool control panel circuit that would fall under NFPA79 rules. Thats a different animal. If wire is Yellow it means a source derived from another location and is only yellow outside of it's place of origin. The color for low voltage DC is blue, and blue with white for grounded DC.(common)
Color is very important, someone could get killed thinking the power is completely locked out and touch a live wire that was supposed to be marked yellow! Find out what rules apply for your situation.
james wuebker
Senior Member
- Location
- Iowa
S'mise said:
Purple is still used for your grounded DC(common) also.
Jim
james wuebker
Senior Member
- Location
- Iowa
S'mise said:
How long have you seen the color blue with white stripe. I do know you are correct but in the mid 90's we were using purple and did notice they started to use the blue with white stripe in the later 90's to 2000. Blue was positive. we used yellow if it feed ext. power to somewhere else. Red was 120v and used black as 240 v. These with wiring in injection molding machines.
Jim
I've been working with controls for over 20 years and I don't think I've ever seen purple wire used. NFPA79 has somewhat evolved with some IEC type rules, but as far as I know Machine tool color codes are the same always, following the old JIC rules (USA). Yellow is commonly used on lighting and PLC circuits also, because they may remain powered after the main disconnect is opened. Red does not have to be 120v, it signifies ac control wires.(switched) I think black is any supply voltage over 150V, but yes its the higher voltage and requires separation from control wires. Blue does not have to be positive, it is any ungrounded DC source. Of course if you are using small multiconductor cable these color rules dont apply. Man where has the last 20 years gone?
John Valdes
Senior Member
- Location
- SC.
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- Retired Electrician
I have worked with controls for most of my career. I also draw the schematics and build the panels.
Since I was usually working with a 480 volt power source those wires would be black. Any DC control wiring would be blue. Blue for all the DC regardless of voltage. Any AC control wiring 24-120 was a picked from the rack. Whatever color that I had on hand. Building control panels is an art. As I said before. Numbering is the key to a safe and reliable installations. You will see many control panels with all the wires the same color. No fear, I have the print.....lol
ps....why purple. The dc return carries the same voltage as the source.
Since I was usually working with a 480 volt power source those wires would be black. Any DC control wiring would be blue. Blue for all the DC regardless of voltage. Any AC control wiring 24-120 was a picked from the rack. Whatever color that I had on hand. Building control panels is an art. As I said before. Numbering is the key to a safe and reliable installations. You will see many control panels with all the wires the same color. No fear, I have the print.....lol
ps....why purple. The dc return carries the same voltage as the source.
I'm sure cost is a major reason why a solid color is used. I've also seen DC Power (blue) and DC Return (yellow) mandated by one organization. I personally didn't have much of an issue with purple, as it's use isn't restricted, but yellow is. Just goes to show the variety of wire color schemes out there.
petersonra
Senior Member
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- Northern illinois
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- engineer
red and white (grounded control voltage supply), or red and red (ungrounded control voltage supply) would work.
However, it is not unusual for a building to have its own unique color codes for this kind of thing. I have seen both purple and orange used for this kind of wiring, usually in HVAC type equipment.
However, it is not unusual for a building to have its own unique color codes for this kind of thing. I have seen both purple and orange used for this kind of wiring, usually in HVAC type equipment.
From an ECM article on NFPA 79
Equipment-grounding conductors (NFPA 79, Sec. 16.1.2 and 16.1.3). You must use the color green, with or without one or more yellow stripes, to identify the equipment-grounding conductor (where insulated or covered). International and European standards require the use of a bicolor green-and-yellow for this purpose (see IEC 204-1 for specific requirements). You can use conductors of other colors, provided the insulation or cover is appropriately identified at all access points.
For grounded control circuits, you may use a green (with or without one or more yellow stripes) or a bare conductor to connect the transformer terminal to a grounding terminal on the control panel.
Sec. 16.1.3 allows you to use other colors for the purpose of identification as follows:
? Black represents ungrounded line, load and control conductors at line voltage.
? Red represents ungrounded AC control conductors, at less than line voltage.
? Blue represents ungrounded DC control conductors.
? Yellow represents ungrounded control circuit conductors that may remain energized when the main disconnecting means is in the OFF position. These conductors must be yellow throughout the entire circuit, including wiring in the control panel and the external field wiring. International and European Standards require you to use orange for this purpose (see IEC 204-1 for specific requirements).
? White or natural gray represents a grounded circuit conductor.
? White with blue stripe represents a grounded DC current-carrying circuit conductor. International and European standards require you to use light blue for the neutral conductor (see IEC 204-1 for specific requirements).
? White with yellow stripe represents grounded AC current-carrying control circuit conductors that remain energized when the disconnecting means is in the OFF position. For additional circuits powered from different sources that remain energized when the main disconnecting means is in the OFF position, you must use striping colors other than green, yellow or blue to uniquely identify the grounded conductor
Equipment-grounding conductors (NFPA 79, Sec. 16.1.2 and 16.1.3). You must use the color green, with or without one or more yellow stripes, to identify the equipment-grounding conductor (where insulated or covered). International and European standards require the use of a bicolor green-and-yellow for this purpose (see IEC 204-1 for specific requirements). You can use conductors of other colors, provided the insulation or cover is appropriately identified at all access points.
For grounded control circuits, you may use a green (with or without one or more yellow stripes) or a bare conductor to connect the transformer terminal to a grounding terminal on the control panel.
Sec. 16.1.3 allows you to use other colors for the purpose of identification as follows:
? Black represents ungrounded line, load and control conductors at line voltage.
? Red represents ungrounded AC control conductors, at less than line voltage.
? Blue represents ungrounded DC control conductors.
? Yellow represents ungrounded control circuit conductors that may remain energized when the main disconnecting means is in the OFF position. These conductors must be yellow throughout the entire circuit, including wiring in the control panel and the external field wiring. International and European Standards require you to use orange for this purpose (see IEC 204-1 for specific requirements).
? White or natural gray represents a grounded circuit conductor.
? White with blue stripe represents a grounded DC current-carrying circuit conductor. International and European standards require you to use light blue for the neutral conductor (see IEC 204-1 for specific requirements).
? White with yellow stripe represents grounded AC current-carrying control circuit conductors that remain energized when the disconnecting means is in the OFF position. For additional circuits powered from different sources that remain energized when the main disconnecting means is in the OFF position, you must use striping colors other than green, yellow or blue to uniquely identify the grounded conductor
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