I know that this topic has been discussed in many other forums but I had a conversation with a customer recently that got my blood pressure up so I thought I would take a few moments to write a post and vent..
It is 2020 and some panel designers here in the USA are still making up wire colors? Really??
News flash folks..there are national and international standards where this has all been discussed and decided years ago. Technically speaking you can use just about whatever color you want if you really want to..but why would you?
Here in the USA the most commonly used standard is the NFPA 79 , this is an electrical standard for industrial machinery. This standard was derived from the NFPA 70 and is referenced in article 670. As of this writing the most current edition of the NFPA 79 is edition 2018 and it gets updated every few years, you can even read the current edition online for FREE, so now you don’t have an excuse for not reading it!
For readers in the rest of the developed world you will want to refer to IEC 60445.
Identification of Conductors
I will direct your attention to section 13.2 which discusses this topic in detail which I will paraphrase here:
Equipment Grounding Conductor
Green or Green with Yellow Stripe
and of course there are several exceptions..
Grounded AC Conductor (N)
White, Gray, and one other that you really should read for yourself in the standard.
Ungrounded AC & DC Power Conductors
Ungrounded AC Control Conductors
Ungrounded DC Control Conductors
Grounded DC Control Circuit Conductor
White with Blue stripe
Now I have seen this in many panels as blue with a white stripe but the standard actually says White with a Blue stripe. I have heard folks complain that this wire is hard to purchase or some other rubbish. Just about any large wire supplier has the ability to provide you with this wire, even if its not on the website, just ask them. Most suppliers will simply load a spool of white MTW into a machine that paints whatever color stripe you want onto the wire. I should also point out that Automation Direct has sold this wire for several years.
Conductors that remain energized when the main supply is disconnected.
(Read the standard for the details)
Ungrounded AC Conductor: Orange
Grounded AC Conductor:White with Orange Stripe
This is one that I have used for ESTOPS that travel from panel to panel. In most cases this will also require special labels on the enclosure door and other considerations. A few years ago the standard also included Yellow but it appears that this has been removed in the current edition which also means the image at the top of the blog is out of date.
Oh.. but in the place I used to work we used BRN, ORG, YEL for 480VAC and BLK, RED, BLU for 240VAC.. Sure you still can do what you want but you will need to add a label to the inside of the cabinet warning folks and now your panel has a mash-up of wire colors. In the NFPA world all power circuits use black wires. Don’t know what voltage they are on sight? Get your meter out and check them first, if you are about to touch them I hope they are 0V.
One more thing..I know that the installing electricians like to pull the colored wires when installing equipment, this help helps them save time when identifying phase conductors, that is until they get into a pull with more than 5 wires or until they run out of one of the colors, then wires get black very quickly.
Authority Having Jurisdiction: AHJ
Lets never forget about the AHJ. The definition of which can be found in Annex A, Section A.3.2.2
This boils down to AHJ = Your Electrical Inspector and/or your Customer. This means that they CAN get what they want and you should always ask them what they expect, do not assume. BUT..ALWAYS mention that there are national standards for this and by adopting them they will simplify the design process, decrease sources of confusion and increase product safety. Yes, I know that its a bit of a sales job, but welcome to reality.
Non Standard Colors
When non-standard wire colors are used they need to be permanently identified with a label on the inside of the electrical cabinet. (NFPA 79 220.127.116.11)
Still don’t believe me?
I have provided a link below to the NFPA website where you can find a link to the free viewer that they provide.
I will also provide here a link to an excellent design guide that is provided by EATON.
if you don’t like clicking link on strangers websites the URL is here..