What's new
What's new

Wire colors, any standards?

Mebfab

Diamond
Joined
Jun 7, 2003
Location
Mebane North Carolina USA
I am wiring a CNC control. Limit switches, E stops, etc. Some 24v some 120.

Question, does a wire color standard exist? I know about white, black, green for 120. But the rest?
 
Judging from the wiring diagrams in our various CNC maintenance manuals, it seems the machine builders arrange colors so that adjacent wires will contrast for easier identification in a bundle. In other words, if everything is the same voltage it doesn't matter what the color is, so long as there aren't two of the same color that might accidentally be switched. Usually the wires in labeled in drawings (org, red, blu, grn, etc).

I once saw a large HBM in the process of being completely rewired after a fire. The guy had run arm-thick bundles of the same red wire, identified only at each end with a stick-on label. I suppose it was inexpensive but if you ever had to test continuity it would be time-consuming...
 
Yes, standards exist.
There is the CE standard and the us semi standard.
My gripe with CE is blue is both low voltage and high.
My gripe with the us is black and red are both low voltage and high.
Google has your answers, 2 hours of research should settle you.
 
... 2 hours of research should settle you.

No. It won't. Only piss him off if he has any less patience than the Rock of Gibralter.

Wire it however is convenient. There is a standard SOMEWHERE that will fit it, and you may be the first person, ever, to actually adhere to it, even if by accident.

Seriously.

Bill
 
Judging from the wiring diagrams in our various CNC maintenance manuals, it seems the machine builders arrange colors so that adjacent wires will contrast for easier identification in a bundle. In other words, if everything is the same voltage it doesn't matter what the color is, so long as there aren't two of the same color that might accidentally be switched. Usually the wires in labeled in drawings (org, red, blu, grn, etc).

I once saw a large HBM in the process of being completely rewired after a fire. The guy had run arm-thick bundles of the same red wire, identified only at each end with a stick-on label. I suppose it was inexpensive but if you ever had to test continuity it would be time-consuming...

Brilliant lad, pun intended. Chinese perhaps, and actually believed 'The East is Red'?

Ye'd need an RF gadget to even get yerself POSITIONED to do continuity testing.

Mind - one could have any wiring jacket colour they liked in a 1942 Monarch 10EE as well.. so long as it was Thomas & Betts blue.

OOTH..IF you could dig far enough in to SEE it - there was a numbered metal ring crimped onto the end of each.

That beat all-Hell out of the world's first Electrocardiogram digitizer. Wire-wrapped. All in white.
Six-foot rack of it. And at the time we had to fly the mag tape output to an IBM mainframe to be deciphered and graphed onto superfold. Now? I suspect it is just one more Android app.

Bill
 
I once saw a large HBM in the process of being completely rewired after a fire. The guy had run arm-thick bundles of the same red wire, identified only at each end with a stick-on label. I suppose it was inexpensive but if you ever had to test continuity it would be time-consuming...
Check out a military aircraft some time... every wire is white, at least everything I've seen (which is admittedly little). However, I did work on some large products that went in to military aircraft, and again, all white wires. And after that experience, I much prefer having an electrician yell over, "look for wire H348 in rack A2" versus "look for the green wire in rack A2" when rack A2 has 10,386 wires in it.

Besides, this is just plain sexy:

Zu4e5wX.jpg
 
Check out a military aircraft some time... every wire is white, at least everything I've seen (which is admittedly little). However, I did work on some large products that went in to military aircraft, and again, all white wires.

Typically in military aircraft components we used all teflon coated stainless high-temp wire, which I have only seen in white.

For commercial wiring, I have seen contractors use pretty much whatever they had on hand, with the exception of neutral being white and ground green.

For industrial control, most builders I have seen stick to some common conventions.

Green or bare is ground, sometimes green with a light green trace.
White is common tied to ground.
Black is high voltage multi-phase, usually with colored tape on the ends for three phase.
Red is AC control voltage, typically 24 -120v.
Blue is DC control voltage, typically 5 - 48v, but realistically anything not powering a working load.
Yellow is used for control circuits that are not switched in the cabinet, i.e. that may still be live when the main disconnect is powered off.

I have seen black used as AC control voltage along with red for multiple taps or line level control (power from a motor to an overload or latch circuit).
 
I could never understand that
High temp in an electrical cabinet?
So if the plane catches fire, the wire will withstand an extra few seconds of "temp" in case THAT might make a difference??

Even worse in some of our applications, a couple of the harnesses had to flex quite a lot and would regularly break conductors. One flat harness in particular was basically a folded clock spring for a gimbal element, and I know for a fact that the original wires were not high temp, but that's all they would allow us to put back in. Glad I wasn't around to see that installation.
 
So if the plane catches fire, the wire will withstand an extra few seconds of "temp" in case THAT might make a difference??

An "extra few seconds" or the equivalent is a fairly common consideration in the design of combat equipment, and has much to do with its high cost. My Dad used to tell me an old saying from his days in the aircraft plants, "Second best in war is last." That's why MIL surplus stuff is never junk. The apocryphal $600 toilet seat was overpriced because of all the ticket-punching associated with vending it to DOD, but it was still probably a pretty decent toilet seat.
 
I could never understand that
High temp in an electrical cabinet?
So if the plane catches fire, the wire will withstand an extra few seconds of "temp" in case THAT might make a difference??

Not just aircraft. My 2007-vintage MEP-803A Diesel gen set has the same all-white, Teflon-family high-temp wire.

And it CAN make a very real difference, and for more than a 'few' seconds. Its predecessor wire was all that was still recognizable when one of our early space capsules suffered a pure O2 fire on the pad. All else was ash, all too-much of 98% water astronauts included.

That can buy enough time for fly-by-wire to get a damaged aircraft to a better situation, if only for more survivable ejection. Munitions might produce an intense, but only short-lived flash. Heavy damage, but only once per hit.

Buy far better time if on board fire extinguishers, luck, or manipulating the air stream can put out a fire altogether and get aircraft and crew back to safety mostly intact.

It is also pretty tough stuff against more mundane threats. Chewing rodents and insects, accidental abrasion and chafing, solvents and corrosive reagents, carelessly handled welding equipment.

Makes field depot repair logistics easier, too. Only one colour to have to fly half way 'round the world and stock in the needful gauges, not two dozen per size.

Enhances longevity of the equipment it is used on as a result of all that. Repair OR replacement costs drop, reliability in reserve storage goes up, even in less-gentle, hence cheaper storage.

Wish more of my tax dollars had as many positive returns on THEIR spend as that ignorant white wire.

Not that DoD cares, but it IS available in solid colours and colour-coded stripes as well. Been using it for years where 'plenum' ratings were called for. With the proper tool, even stripping it is easy. ELSE NOT!

Bill
 
On some Italain and German machines each wire has a unique wire# printed on every 10cm
And those # are on the diagram too
The best I have seen so far

BTw Neutral is bleu over here and ground yellow/green

Peter
 
Pretty much the only global std thats common is to avoid using what ever your std ground wire colour is for anything but grounding.

IMHO tracability and fixing is far more aided by labels - numbering than conductor colour alone, yeah it helps but on anything more involved than a auto, colours alone don't give you enough connections!
 
The UL508A standard lists internal power wiring colors for industrial controls.

NFPA 79 is the general guide for machine tools.

There are also international standards. If this is for anything that will be exported the necessary standards will have to be followed.

One caution - there has been mention of confusion where the same color is used for both high and low voltages. Good safety practice requires separating high voltage and low voltage into separate bundles.

Look up "Separated or safety extra-low voltage" (SELV) for the definition of low voltage.


Edit: Regardless of color or ID labels all modern standards, especially ISO, require careful documentation of all connections. Even when there is no specific polarity requirement a "polarity" must be assigned and followed. You can't connect the right hand side wire to pin 1 on one unit and pin 2 on the next. With such documentation wire color and labels are an aid to troubleshooting, not a necessity.

Whatever else you do I strongly recommend using the euro style green wire with a yellow tracer for earth grounds.
 
Pretty much the only global std thats common is to avoid using what ever your std ground wire colour is for anything but grounding.

IMHO tracability and fixing is far more aided by labels - numbering than conductor colour alone, yeah it helps but on anything more involved than a auto, colours alone don't give you enough connections!

Before fibre optics, we did manage to muddle-through with colours on up to 600 pair telco cable. OTOH, we read those colours AS 'numbers' and DO work 'em in pairs and groups of pairs, so it is way easier than it sounds. Just TEDIOUS as drying paint...by hand.

:(
 
Almost every panel I have dealt recently had the CE sensors - brn/blu/blk/wht scheme for low voltages with blu or blu/wht for +24, and wht for 24com.
That seems to be sinking in across the board because sensor cables are being built to CE.

This is a problem, since blue is +24 in panels but is 24com in the sensor cable, and wht is 24com in the panel.

AC is a total clusterfuck..
Here, use our standard of:
grn for ground
wht for current carrying neutral
anything else is hot...but typically blk,red,ong,yel

Opening a euro cabinet...hire someone.
Opening a Japanese cabinet...hire someone and a shinto priest.
 
All the wiring and cabling I did on aircraft was stamped from end to end with the wire number as it was listed on the wiring diagram. The average aircraft retrofit took at least 5 miles of wire. Back then it was all white mil spec. 22759. I had two women that could read the print. stamp the wire numbers and solder them into a
connector neat as you could ever see on a plug. The average plug had at least 50 wires, mostly PTO-6E series. I still have all my wire stamping equipment. It is a hot stamping system and does not rub off. The manual machines and some of the earlier CNC machines would number each wire on the print with the low numbers were the power carrying ones. They would use a letter after the number A, B, C, to designate the way the power flowed and the way it was connected. A would be the power source. when it connected through a relay the outgoing wire would be B. Simple but effective for troubleshooting.

John
 
A good place to start would JIC (Joint Industrial Council) This used to rule the industrial segment a few years ago. Whether they do today I am not sure.

Check with Motion Guru, he would know.

Tom
 
Opening a Japanese cabinet...hire someone and a shinto priest.

Jabatan Telecom, Brunei was the only client that had the budget and actually DID that. Flew 'em in and housed 'em rather than touch a wire themselves. Surely didn't accept no Shinto priests in that enclave, though!

Otherwise, Taiwanese, many of 'em Ma bell trained in the USA, ELSE Koreans.

Or Danes.

Oldest telecoms in Asia were their work (Great Northern) as much as C&W (Eastern Telegraph), and they've never colonized, drug-addicted, shot, shelled, bayoneted, burnt-up, nor bombed anyone out that way.

Some folk have seriously long memories about that sort of rudeness.

Bill
 








 
Back
Top