Electrical wiring color code standards

I like having DC+ and DC- distinguishable. DC+ is conventionally solid blue. Blue with white stripe is fine for DC-, but it's a special order. For a medium or large panel shop that's no problem.

I build some simple control panels in my garage, the others I send to a panel shop. It's not worth my while to buy a spool of blue/white, so I use gray for DC- in that case.

One glitch in wire coloring schemes arises with solar powered panels. You can chain two 12VDC solar panels together to make 24VDC, but one 12VDC solar panel with 12to24DC converter for analog loop power is simpler and less expensive. Control Microsystems has a niche market with 12VDC controller and an internal 12to24VDC converter to power analog loops. So you're left the problem of clearly identifying both 12VDC and 24DVC wires. There's no shortage of colors, but I'm not aware a convention to deal with that. To make matters worse, telecom equipment uses 48VDC with a positive ground as a standard.
 
Google ...

Electrical wiring - Wikipedia, the free encyclopedia and down to Colour code common wiring safety code
 
I read another posting and i thought i understood it. Here, i read again and now i'm confused. Have u ever thought that ur posting might be read by a lay man (like me who wants to fix the plug of my washing machine and not sure which to connect to which)?
 
A

Amish Electrician

> Google ...

> Electrical wiring - Wikipedia, the free encyclopedia and down to Colour code
> common wiring safety code

Really? If you are using wikipedia or google for a reference guide to electrical work, then you shouldn't be performing the work.....period!

Neutrals and grounds are the only colors specified, once a color scheme is established, then it must be continued throughout the facility.
 
i agree, and make sure your schematic is clearly stated with wire colors and then all questions should be answered
 
While most posts are correct regarding UL508A for the wire colors the best advice I would give is that anyone wanting to design/build enclosures and machines to spec should purchase the UL508A, NEC and NFPA-79 revisions currently approved and released. For example I have had customers use orange wire for interlocking power sources (both AC and DC) while others have insisted on use of a color stripe to note the power type as defined in UL508A. Although this does not follow the letter of UL508A it demonstrates that yellow is not the only color approved for power sources not removed with the system/panel disconnect means. I also noted that DC grounded systems also require white/blue stripe common whereas ungrounded DC circuits need blue/white stripe. A copy of current specifications is money well spent.

James Ulinski
Controls Engineering
ROI Industries.
 
A very colorful discussion indeed and like Ruf, I am a bit confused too. This is what happens when you've numerous standards! Why can't all these highly professional bodies come together and agree on common color code standards of wires for use in various applications? Will save lot of confusion and, maybe, accidents. Is it ego that prevents this from happening or is it really a more complex issue? Remember the problem the Hubble telescope's mirror encountered when it was realized that engineers forgot to do the correct conversion from inches to centimeters (or visa-versa)?!
 
B
There are color coding standards. They are just different for different areas of the world and different applications.
 
I don't get it, so many replys, but i did not find what I was looking for.

Example:
Control panel for 3 Phase electric motors.

-Supply Voltage 480V 3Ph
-Transformer inside the Panel for "CONTROL VOLTAGE" 220V for example
-Now inside this panel there is Supply High voltage AND control voltage.

Don't you think you want to have a different color wire for the control voltage than the supply voltage????

And what would be the wire colors for this panel???
 
B
If you are in the US, you could use UL508a or NFPA79 for wire color coding inside of control panels.

NFPA79 can be viewed at the NFPA web site for free.

Normally in the US we would not use 220V as a control voltage.

The US national electrical code does not specify color coding of conductors other than for equipment grounding conductors (green) and grounded conductors (white or gray). There is also a color code for the high leg on some power systems. But that is it. Nothing else is required. You can wire the power feeds in purple if you want to. You just cannot use green or white (gray) for anything but their intended purposes.

--
Bob
http://ilbob.blogspot.com/
 
C
Let me help you. Yes, there should be standards. And there are, lots of conflicting standards. Even the recognized standards bodies seldom agree. Control systems are sold by anyone to anyone and the better vendors have a standard, their own. And many buying companies have standards. It's quite likely my standard wouldn't pass inspection in your area. In the end, I do what I think is right, based on the schemes that make the most sense I've seen over a broad range of foreign and domestic equipment along with requirements of the NFPA and if necessary the whim and fancy of local authorities. But. no matter what you do, it probably matches someone's standard. I've seen entire systems done with black wire.

Regards
cww
 
B
CWW

There are no major conflicts between the consensus standard NFPA79 and UL508a. Between them, they represent the most commonly used control panel wiring standards. They grew out of older standards that were quite similar.

You have to remember that you are involved in a fringe area of control systems by doing your own thing. It is not by even a remote stretch something that is the norm.

I would also point out that NFPA79 only applies to machines and would not apply to process systems or gas turbines, among other things.

I do not know of any standards bodies in the US that have any conflicting standards for wiring of control panels. They were long ago harmonized. Perhaps if you know of any such anomalies you could point them out. I am aware of a single minor issue between NFPA79 and UL508a. NFPA79 requires certain wires be orange while UL508a allows them to be either orange or yellow. That is it to my knowledge.

perhaps you could list the "lots" of conflicting standards you claim to be aware of.

--
Bob
http://ilbob.blogspot.com/
 
C
Hi Bob

We are global these days and the majority of packaged systems I am seeing are from the EU. And while the two most quoted American standards bodies are in harmony, if not complete agreement, they are at odds with IEC or whom-so-ever picks coloring schemes in the member countries of the EU. And a lot of the older equipment seemed not to have any particular standard at all. And for that matter I haven't seen a great deal of compliance here either. Beyond the safety mandated grounding and house power connections, small systems tend to be all over the map with no color coding, all black for example seen from time to time. One US company I've seen even likes to change colors along a signal line and use yellow (power from outside the enclosure) for ESTOP and safety interlocks. The stuff I build does lean on the US standards. But it you see a variety of systems, from a variety of places and a variety of vendors you can't make any assumptions. Guess what a white wire with orange and purple stripes means.

Regards
cww
 
B
If you are buying packaged equipment from the EU that does not meet US standards, whose fault is that?

I agree there are some very low end suppliers of control systems and/or machines that will give you junk. Whose fault is it for accepting that?

But the fact is that those kind of systems just are not the norm in US industry in general. Maybe they are where you work, but they just are not in the US in general.

BTW, how do you manage to meet the various safety requirements if the products you are accepting do not meet accepted US standards? Including the OSHA requirement that control panels be listed? How would you even go about making a proper safety evaluation of them?

If they do not meet US standards for one thing they probably don't meet it in others. Do they have US short circuit current ratings? If not, how could you even wire them up?
 
C
Excellent questions, Bob.

The problem is that for example, I don't think you can buy a printing press made here. And they are massive and complex, a huge undertaking and not made to order. So if you want to be in the business........ Often it requires working with the local officials and a few adaptations. I don't know how they satisfy OSHA but those things are negotiated on installation. Many other specialty machines are like that. Take it or leave it. If you are commissioning a system to be built, you may have a choice. An yes, it is lunacy to have a dozen different brands of PLC, but that's how it happens. I had a little influence on the semi custom items, but.....

Regards
cww
 
B
> I don't think you can buy a printing press made here.

==============

You might be right, but you can get them made with control systems that
meet US standards. But, the company has to want to do it.

--
Bob
http://ilbob.blogspot.com/
 
Did you ever get an answer? This is the standard I inspect for, if the client(AHJ)does not have their own standard specified. It is generally recognized by municipalities, water & wastewater, and city utilities for MCCs, industrial control panels & field wiring.
Power:

480V A phase = Brown
480V B phase = Orange
480V C phase = Yellow
480VAC neutral = grey

Ground is always green, green w/ yellow stripe or bare copper.
Use tape at every termination, to color code wire, only if colored insulation is not available due to large AWG.

3 phase 240 / 208 VAC Power
A phase = Black
B phase = Red (orange if high leg)
C phase = Blue
1 phase 240/120VAC Power
L1 = Black
L2 = Red
Neutral = White

AC CONTROL
120VAC Panel = Red, Field = Violet, Foreign circuit = Yellow
DC Control Generally =Blue, or light blue
After this it varies much more than the above list.
DC power supply wiring:
12 VDC+ =DARK BLUE
12 VDC- =BLACK/RED STRIPE
24 VDC+ =PINK
24 VDC- =BLACK
SHIELDED PAIR +red, or white, or clear, -black.

I work for a specifying electrical engineer in Northern California. I am a licensed ICC electrical inspector & an OSHA Outreach Safety Trainer. I hope this helps & be safe.
 
My question is in regards to the UL color code " Orange - ungrounded control circuits or other wiring, such as for cabinet lighting, that remain energized when the main disconnect is in the "off" position".

If the external wire is connected to a breaker on the subpanel of an enclosure, then wired to a 24vdc power supply, is the wire between the breaker and the power supply still orange?

Also, are the wires on the load side of the 24vdc power supply orange(+) & orange w/ white stripe(-)? Or, should they be blue(+) and white w/ blue stripe(-)?
 
B
Take a close look at what 66.9.1 f says versus 66.9.1 g.

Orange with a white stripe is not listed anywhere. White with an orange strip is only used for AC grounded control circuits not disconnected by the disconnecting means. the DC circuits would still be covered by 66.9.1 c and f.
 
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