Wire Color Codes - Page 1
Forum section: electronics / beginners

author: jsi
author_rank: Regular Contributor
timestamp: March 11, 2016, 11:31:30 pm
content: I've done a fair bit of household wiring (USA building codes if that matters) and I was taught to never use the black wire for anything but power. (except for the exceptions) Now my new hobby in low voltage electronics is making me a bit crazy because black seems to be the standard for ground. Is there a standard for wire colors in low voltage stuff the same way there is for the mains?(I'll get over it, but everytime I connect a black wire to ground I have to think really hard, this is OK, this is OK.)

author: dom0
author_rank: Super Contributor
timestamp: March 11, 2016, 11:33:26 pm
content: No

author: liquibyte
author_rank: Frequent Contributor
timestamp: March 11, 2016, 11:56:19 pm
content: I always use red for positive and black for negative and green for ground with exceptions. If I want to wire an off board transistor for instance, I use black for the collector, red for the emitter, and green for the base. There is no standard that I'm aware of so it boils down to preference or even what you have on hand for that matter.

author: Andy Watson
author_rank: Super Contributor
timestamp: March 12, 2016, 12:00:59 am
content: Quote from: dom0 on March 11, 2016, 11:33:26 pm+1Where possible, you could twist live and neutral together. This would aid identification and reduce EM fields generated by the mains current. Otherwise, keep a clear head and double and triple check your wiring!

author: Brumby
author_rank: Unknown
timestamp: March 12, 2016, 12:46:33 am
content: Quote from: liquibyte on March 11, 2016, 11:56:19 pmI tend to follow this basic approach - with using yellow as a higher supply voltage (blame my exposure to computer PSUs).Mains wiring in Australia used to be Red (active) Black (Neutral) and Green (earth), but now we use the Brown/Blue/Green with Yellow stripe.The only other practice I like to follow is when using flat rainbow cable, to follow some logical mapping of the colours to the numeric values associated with the resistor colour code. eg Data line 0, 1, 2, 3 ..... etc to black, brown, red, orange ....But that's just one of my personal quirks.

author: Dinsdale
author_rank: Regular Contributor
timestamp: March 12, 2016, 04:26:31 am
content: PCs are "low voltage". Most power supplies in that application have settled on a standard. I try to follow that.I'm trying to locate the "Bomber's Color Code". You know, "Cut the red wire... No, No, the yellow wire,the yellow wire!"

author: Richard Crowley
author_rank: Super Contributor
timestamp: March 12, 2016, 04:36:30 am
content: The North American standard for power where white = neutral and "hot" is black (or red or blue or orange, etc.) isn't all that intuitive. But, honestly, why the Europeans chose blue for "neutral" and brown for "hot" is even more bizarre and arbitrary, IME. Even as I write this I wouldn't bet my life that is correct because it just seems so completely random.For DC power wiring inside gear, my standard is black for common, and red for the primary positive rail. While violet is the primary negative rail.Other positive voltages can be yellow, orange, etc, while other negative power rails can be blue, gray, etc.Green is reserved for chassis ground, mains safety ground, etc.

author: bills
author_rank: Frequent Contributor
timestamp: March 12, 2016, 04:45:54 am
content: I use white, black ,green for AC.red for + dc biack for - dc .HV Same as AC.hope this makes sense.

author: obiwanjacobi
author_rank: Super Contributor
timestamp: March 12, 2016, 06:21:01 am
content: Look at a PC PSU - I believe it uses some sort of standard...

author: Simon
author_rank: Unknown
timestamp: March 12, 2016, 07:14:20 am
content: No there is no standard although black seems to be fairly standard for negative which we tend to call ground in our circuits although it's not the same ground as earth ground. If you want real complication you can ask the Germans who decided to make brown negative and black positive which is really mad. I think a lot of people would probably follow power supply coding from computers and use red for positive and if there is more than one positive probably read for 5 V and yellow for 12 V or any other major high-voltage but that's just what I would do if I had a choice and had to make a decision. There is no code.

author: Shadetreeprops
author_rank: Regular Contributor
timestamp: March 12, 2016, 08:24:53 am
content: I have used yellow with a red stripe to indicate pos, and regular yellow for neg. I have also used White for everything, normally it just boils down to how much of what wire i found in a dumpster, and how much do i need for said project.My homemade PSU, would drive anyone mad, cause i have colors cris crossing each other. if i was not the one who made it, i would not make head or tails of what was going on with it..but for alot of low volts i have seen this. RED pos, Black Neg, Yellow or Green as Ground.. but for my PSU, the power brick, the 12v is yellow, and the 5v is red, black is ground, and blue is what i have to short red to, to get it to stay on, or use it as my switch.

author: miceuz
author_rank: Frequent Contributor
timestamp: March 12, 2016, 08:45:19 am
content: There is no standard, but It's a good practice to design your own and stick to itFor me it's like this:red, orange - vccblack - gndyellow - sckblue - data coming from slavegreen - data coming from masteretcMakes debugging much easier

author: German_EE
author_rank: Super Contributor
timestamp: March 12, 2016, 08:52:47 am
content: My standard color scheme is:Red +12VOrange + Anything above 12VYellow + Anything below 12VGreen AudioBlue -12VViolet Power switchBlack Used for internal wiringWhite Used for internal wiringBrown Low voltage ACCopper colored coax RF circuitsBlack colored coax Audio circuitsMains wires follow the standard European color code of blue/brown/green & yellow but are wrapped in either transparent heatshrink or plastic spiral wrap to differentiate them from standard voltages.

author: android
author_rank: Regular Contributor
timestamp: March 12, 2016, 09:11:02 am
content: I always use orange for SCK ... easy way to remember: Clockwork Orange

author: LordHexahedron
author_rank: Contributor
timestamp: March 12, 2016, 10:58:49 am
content: no objective standard, typically red for hot, black for neutral, green for ground.I use the standard:reds (pink, red, orange) - powerblacks (black, dark green, dark blue, other dark?) - neutralgreens (green, yellow, beige) - groundeverything else (light blue, purple, white, others) is either data or to make it easier to debug - if it's ambiguous I mark it.My wiring must be hard to read for colorblind people, I use all the colors I can get my hands on

author: dom0
author_rank: Super Contributor
timestamp: March 12, 2016, 12:44:06 pm
content: Quote from: Richard Crowley on March 12, 2016, 04:36:30 amBlue is neutral. Phases are brown, black and grey (in that order L1... L3). Doesn't matter for normal appliances, though, because you generally can't know which one is hot and which one is neutral.I don't think there is any way to make these colours not arbitrary. Okay, "red" for "hot", maybe, but other than that...

author: Jeroen3
author_rank: Super Contributor
timestamp: March 12, 2016, 12:57:32 pm
content: Most of the time I encounter this:Ground - Green/Yellow. Not allowed to carry current.Neutral - Blue.Phase 1- Brown.Phase 2- Black.Phase 3- Grey.If three phase, they come in pairs. Should be easy to recognize.Switched phase - black.Often you'll find just Blue and Black for 3 phase. The standards are not very strictly enforced. Could just be what cables are in discount that month.Apart from ground, everyone uses the same for ground, green/yellow wire. Which is good.But I've recently seen an installation using Blue, Brown-Grey-White for 3 Phase, removing the ambiguity of black. DC 24V was red/black. Other colors were sensing and signalling.The first page of the schematic often tells you what color "standard" they used.

author: tooki
author_rank: Super Contributor
timestamp: March 12, 2016, 01:19:40 pm
content: Quote from: dom0 on March 12, 2016, 12:44:06 pmI thought I read somewhere that those colors (blue/brown/black/gray plus striped green-yellow for ground) were chosen because they can be distinguished by people who are color-blind.(That's also the reason the default color scheme in early versions of OS/2 was so hideous. It wasn't chosen for aesthetics.)

author: Zero999
author_rank: Super Contributor
timestamp: March 12, 2016, 03:06:43 pm
content: Quote from: Simon on March 12, 2016, 07:14:20 amThere is no standard for the colour of wiring inside appliances, whether it be AC or DC, regardless of the voltage.In the EU, there is a standard for DC wiring inside buildings. The colours are identical to AC wiring, with blue being the earthed current carrying conductor, brown for positive, grey for negative and green/yellow for protective earth.http://electrical.theiet.org/wiring-regulations/cable-colours/harmonised.cfm?type=pdfhttps://www.eca.co.uk/filelibrary/download/?FileID=1295

author: Neilm
author_rank: Super Contributor
timestamp: March 12, 2016, 03:36:16 pm
content: Quote from: Hero999 on March 12, 2016, 03:06:43 pmNot quite true - IEC61010 specifies that earth is only on Green / Yellow wire, and the wire should not be used for anything that is not earth.

author: vk6zgo
author_rank: Super Contributor
timestamp: March 13, 2016, 01:24:55 am
content: There used to be one:-http://wikibin.org/index2.php?option=com_content&do_pdf=1&id=8689I tend to use a modified version of this,with the highest DC +ve voltage ----Red,The next highest --OrangeThe one below that--PinkAll are "sort of" versions of RedI can't ever remember us using Grey for Mains in Oz---usually it was whatever the power cable used to the power switch,then whatever the transformer primary was,after that.PMG/Telecom Aust used Red & Black for their 24v supplies.One place I worked decided it would be a wonderful idea to use Blue for +24v----go figure!

author: Muttley Snickers
author_rank: Unknown
timestamp: March 13, 2016, 01:47:34 am
content: The plate pictured below is not one of mine and I only grabbed it for the rotary switch and sometimes you just have to deal with what the fellow that went before you did, in our industry we deal with a wide variety of multicore cables and there are some adopted practices but we never take it for granted that someone else does the same.It might be the black wire ?.......

author: cs.dk
author_rank: Unknown
timestamp: March 13, 2016, 07:29:06 am
content: Yes,It's always the black wire, when somethings wrongFrom a day at work - 1x80 core + 1x25 core all black;(Before dressing it up, and make it look nice)

author: PTR_1275
author_rank: Frequent Contributor
timestamp: March 13, 2016, 11:47:59 am
content: I work on caravans a lot here in Western Australia, we always use red is positive, black is negative. There are standard "other colours" for trailer plugs and wiring, but nothing further than that.Some of the big van manufacturers are pains in the ass because they have adopted the American 110v wiring code for their 12 volt systems, therefore black is positive and white is negative. Because of this I never trust anything I work on, whether it be on the bench or in a van. I always check the polarity of anything I've not done myself within the last day.

author: cs.dk
author_rank: Unknown
timestamp: March 13, 2016, 03:08:24 pm
content: Quote from: PTR_1275 on March 13, 2016, 11:47:59 amI agree.. Volvo trucks also uses white as negative. Every manufacturer does it their ways. Sad there isn't a standard.In general on trucks or cars I use red as B+ (Kl.30), black or purple as Ign+ (Kl.15), brown for ground/chsssis, yellow (Kl.58) light, blue reverse-signal, green handbrake-signal.On mains i have to follow the code; Blue for neutral, brown/grey/black for fases, and yellow/green for PE.. In some older Danish installations, red are PE

author: mtdoc
author_rank: Super Contributor
timestamp: March 13, 2016, 10:03:14 pm
content: It's particularly confusing here in the USA when working on PV systems where you are often transitioning back and forth between DC (black negative, Red Positive) and AC, where black is "live" and white is "neutral" and usually tied to earth ground. Code specifies bonding DC battery negative to earth ground - further confusing things.

author: Jeroen3
author_rank: Super Contributor
timestamp: March 14, 2016, 08:14:03 am
content: I can understand that the negative of a DC circuit is tied to ground at the battery since AC Neutral is also tied to ground at the transformer.

author: SL4P
author_rank: Super Contributor
timestamp: March 14, 2016, 09:50:51 am
content: The mashup described in the preceding comments - explains why mains wiring should be done by a locally licences electrician!For ELV projects, I stick withVas/0V/GND black+5Vcc red+12V yellowthen I start looking for 'as close as I can' standards...

author: Dave Atom
author_rank: Contributor
timestamp: March 14, 2016, 10:32:37 am
content: Red to Red,Black to Black,Plug it in,And stand well back.Always worked for me

author: Zero999
author_rank: Super Contributor
timestamp: March 14, 2016, 01:24:02 pm
content: Quote from: Muttley Snickers on March 13, 2016, 01:47:34 amIf you look closely, the cable cores are numbered which is quite common in multicore cables.Quote from: Neilm on March 12, 2016, 03:36:16 pmThat doesn't apply to domestic/office equipment though, so something like a PC could use any colours.I don't have access to the standard you've referenced to but EN60204 says:Black = AC or DC powerRed = AC controlBlue = DC controlOrange = safetyGreen & yellow PE and nothing else, which agrees with you.Link:http://www.yuntongglass.com/upfile/2012031917030348602.pdfPages 76 & 77.

author: dom0
author_rank: Super Contributor
timestamp: March 14, 2016, 01:51:10 pm
content: I'm pretty sure the IEC standard says that green-yellow must only be used for PE, independent of context.

author: richard.cs
author_rank: Super Contributor
timestamp: March 15, 2016, 11:31:18 am
content: Quote from: Richard Crowley on March 12, 2016, 04:36:30 amIt's the compromise you get when trying to select colours that aren't ambiguous when mixed with the many different previous systems across multiple countries. Blue had never been a phase colour in single phase systems (but had been L3 in the UK) so it was a reasonable choice. Brown is a bit worse, it was earth in the UK though not for long (1934-1939). Red had been used for just about everything, as had black. But the blue/brown combination hadn't been used anywhere before. Black L2 and Grey L3 were the result of the UK pushing for different phase colours, in much of Europe it's normal to use 1 phase colour and a rotation tester (which is usually good enough but doesn't get you absolute phase).Personally I liked the old UK system with the three primary colours as the three phases, it seemed reasonably logical and with colours for phases black follows as a sensible choice for neutral.

author: Zero999
author_rank: Super Contributor
timestamp: March 15, 2016, 01:30:53 pm
content: Quote from: richard.cs on March 15, 2016, 11:31:18 amMe too. There was no need to standardise with the EU for fixed wiring. I can understand the need for equipment exported to the EU but the colour of the wires, in buildings here in the UK, is none of their business

author: LaurentR
author_rank: Frequent Contributor
timestamp: March 15, 2016, 07:20:58 pm
content: Even though a lot of car OEM harnesses use totally random colors, basic car audio aftermarket harnesses are fairly standard (Metra/EIA).http://www.the12volt.com/caraudio/headunitharness.aspMemory / Constant 12V(+) YellowSwitch / Accessory RedGround BlackIllumination Orange/WhiteAntenna Remote BlueAmp Remote Blue/WhiteLeft Front (+) WhiteLeft Front (-) White/BlackRight Front (+) GreyRight Front (-) Grey/BlackLeft Rear (+) GreenLeft Rear (-) Green/BlackRight Rear (+) VioletRight Rear (-) Violet/Black

author: retrolefty
author_rank: Super Contributor
timestamp: March 15, 2016, 08:42:53 pm
content: It can be very disheartening the lack of standards sometimes. At the refinery I worked at the various plants, maybe a dozen, each had a different central control house with many many 4-20ma 50 pair cables running from house to plant instruments and valves. 50 pair twisted shield white/black was the most frequent cabling used. However some plants used white for the +24 loop power and black for the loop common/ground. At the next plant it would be the opposite. It came down to when the plant was built which project 'standards' were used. Best to always measure over assuming. Kind of a measure twice cut once thing.

author: ROBOT
author_rank: Contributor
timestamp: March 15, 2016, 10:35:31 pm
content: Not really a standard but whenever working with low voltage stuff black is almost always ground and red would be +5v. I tend to use orange for 3.3v.

author: N2IXK
author_rank: Frequent Contributor
timestamp: March 17, 2016, 04:21:12 pm
content: Back in the vacuum tube era there was a RETMA standard color code for internal wiring of electronic gear:Black - Grounds, grounded elements and returnsBrown - Heaters or filaments, off groundRed - Power Supply B-plusOrange - Screen gridsYellow - CathodesGreen - Control GridsBlue - PlatesViolet - not usedGray - AC power linesWhite - Above or below ground returns, AVC, etc.

author: Cerebus
author_rank: Super Contributor
timestamp: March 17, 2016, 10:48:39 pm
content: Quote from: Hero999 on March 15, 2016, 01:30:53 pmThe argument would be:1) Free mobility within the EU. If you're an electrician it lets you move between EU countries more easily.2) Market equalities. If you make cable in the UK you can sell the same cable in France, Germany etc. etc. You only have to meet one set of regulatory requirement for the whole EU, rather than one for each country. I've noticed that people are starting to specify cables by european type numbers rather than the UK IEE/BASEC numbers, which used to be standard practice in the UK. (e.g. H07V-R instead of 6491X)