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Electrical wiring colour codes:
This article describes the electrical wiring color code conventions for 120V or 240V AC circuit wiring in buildings in Canada, the U.S., the U.K. and the I.E.C. Quoting from authoritative codes & standards for each region we provide a table summarizing the current and prior wiring color code conventions used by electricians in building wiring.
For each color code table we include authority citations and links to sources of codes, books, standards and wiring guidelines. We point out with photo-examples that while wire color code theory is nice and all that, in the real world of working on existing buildings, wires are not always reliably color-coded and colors may in fact be impossible to discern. Some of the wire color images here were adapted from data provided by the Malta Resources Authority's excellent document on Harmonisation of Wiring Colour Codes - cited below.
We also provide a MASTER INDEX to this topic, or you can try the page top or bottom SEARCH BOX as a quick way to find information you need.
Building Electrical Wiring Color Codes & Conventions for 120V or 240V A/C Circuits
This new type NM-B 14-3 electrical wire has color coded conductors that are easy to spot and understand:
Black - use for line voltage or "hot" wire
Red - a second line voltage or "hot" wire
White - neutral
Bare - protective ground
But as we will illustrate below, on some older buildings spotting any color at all in the wiring insulation or jacket can be difficult or even impossible. Here are links to the electrical wiring color code conventions used by various countries.
1. 2012 Canadian Electrical Code (CEC) - see http://shop.csa.ca
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This knob-and-tube electrical wiring photo has useful information for the electrician or building inspector.
First we can see that if we're in luck, the fabric portion of the wiring insulation may be intact and may clearly show that one conductor is white (neutral) and the other black (hot). With age the white insulation may have become tan or even brownish in color.
Second I'm a bit nervous about how that white wire is stripped back and is in contact with the hot black wire (arrow).
Finally, of course there is no protective ground on this circuit - we've got just two wires with which to contend.
120V / 240V A/C Electrical Wiring Color Codes & Conventions: U.K. United Kingdom
New wiring colour codes replaced existing red & black phase & neutral conductors (left) with brown and blue (right) beginning in 2005. Where extensions or new work can result in mixed wiring colours, a warning must be fixed near the distribution board stating: CAUTION: this installation has wiring colours to two versions of BS 7671. Great care should be taken before undertaking extension, alteration or repair that all conductors are correctly identified.
Regulating authority, IEC AC
I.E.E. Regulations (UK Standard BS 7671:2001) Requirements for Electrical Installations, IEE Wiring Regulations, Sixteenth Edition Amendment No. 2: AMD 14905, March 2004
"New Fixed Wiring Colours - A Practical Guide", www.nicelc.org.uk
"The IEE, ELectrician's Guide to the building regulations, including Approved Document P: Electrical Safety in Dwellings, Chapter 11" Malta Resources Authority, "Harmonisation of Wiring Colour Codes, Practical Guidelines",
Three phase wiring colour codes & color changes are shown just below:
This wiring shown above - well don't even think about figuring this out by color codes. Someone has just grabbed a piece of yellow wire and a blue wire, left an open splice, and jury-rigged something (not shown in our photo).
But when you see obviously amateur electrical--wiring like this it's a red flag to watch out, asking "what else did this fellow wire in this building?"
120V / 240V A/C Electrical Wiring Color Codes & Conventions: Europe - IEC
Wire Insulation Color
Alternative Wire Colors
Line voltage, single phase
Abbreviation: BN, BK
Line voltage, 3-phase
L1 is brown, black alternate
Line voltage, 3-phase
L2 is black, brown is an alternate
Line voltage, 3-phase
L3 is grey, brown and black are alternates
Abbreviation: GY, BN, BK
Green + Yellow stripe
Protective Earth wire
Regulating authority, IEC AC
Table of Wire Color Code Abbreviations 
Color Abbreviation Code
Ivory (Cream in some countries)
Natural (no pigmentation)
Smoke (light gray)
 In the U.S. UL (the Underwriter's Laboratory) has published wiring color acronyms and abbreviations. We have included the standard wiring color code abbreviations along witht the full color name in our tables of wire color standards in the article above. - retrieved 24 Feb 2014, original source: http://industries.ul.com/plastics-and-components/plastics/color-codes-and-abbreviations
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(Mar 12, 2014) Keith E. Davis said:
Tell me is there an excepted convention as to the abbreviations of electrical wiring color codes?
In the U.S. UL (the Underwriter's Laboratory) has published wiring color acronyms and abbreviations. We have included the standard wiring color code abbreviations along witht the full color name in our tables of wire color standards in the article above. Thanks for asking.
Also see UL Standard 83 - Thermoplastic-Insulated Wires and Cables
Question: ok to reverse red and black wires?
(July 18, 2014) Eric said:
Does it matter if the red wire and black be reversed?
Eric without knowing what's being wired all we can say is ... Yes it might.
Generally in house wiring the red wire is a second 120V circuit on a different "phase" such that it can either provide 120V to a device or if wired along with the black wire to two terminals on some devices (such as a 240V motor) the circuit will be provided with 240V. In a 240V circuit generally which terminal gets the red and which the black won't matter.
Question: wiring an electric 600V water heater in Canada
(Sept 11, 2014) Bob said:
For Canada, 600V unit, water heater, does the ground wire have to be green/yellow or just green?
I'm referring to internal wiring, sorry.
Bob Here's a quick summary of colour conventions for the protective ground wire:
The protective ground wire (listed as green-yellow in CURRENT codes & standards) is green with yellow stripe in the UK and IEC.
In the U.S. the ground wire might be bare, or green-yellow (preferred) or green (alternative)
In Canada the ground wire (Protective Ground or labelled PG) can be green-yellow OR green.
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Simpson 260® Series 6XLM
Volt-Ohm-Milliammeter Instruction Manual, retrieved 9/5/2012, original source: http://www.simpsonelectric.com/uploads/File/datasheets/260-6xlm.pdf, [copy on file as Simpson_260-6xlm.pdf]
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