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.

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.

Article Contents:

• ELECTRICAL WIRING COLOR CODES
  • I.E.C. I.E.E. ELECTRICAL WIRING COLOUR CODE CHART
  • U.K. ELECTRICAL WIRING COLOUR CODE CHART
  • U.S.A. ELECTRICAL WIRING COLOR CODE CHART
  • WIRE COLOR CODE ABBREVIATIONS

Notes to the table above

Wiring color code standard sources:

1. National Electrical Code 2011 (NEC) - see http://www.nfpa.org/ (adopted in all 50 U.S. states)

2. UL508A, Section 66.5.3 & 66.9

3. NFPA 79, Chapter 13 - see http://www.nfpa.org/

Some sources include red with white tracer line = switched neutral

On older wiring such as this rubber and fabric-jacketed household wiring from a U.S. home, figuring out what the heck the wire colors are can itself be a challenge.

Look closely at the fabric covering of the two wiring strands in our photo.

The upper wire is the "white" or neutral wire.

The lower wire, whose fabric insulation is black with red and white tracer threads is the "black" or hot wire.

But sometimes there is no clear color distinction between the two wires: you'll need to trace the wiring and use a DMM or VOM to figure out which wire is "hot" and which is neutral or ground.

Notes to the table above

1. 2012 Canadian Electrical Code (CEC) - see http://shop.csa.ca

Mississauga Office 5060 Spectrum Way, Suite 100 Mississauga, Ontario Canada, L4W 5N6 Toll-Free: (800) 463-6727 Tel: (416) 747-4000 Fax: (416) 747-2473
Edmonton Office 1707-94 Street North West Edmonton, Alberta Canada, T6N 1E6 Main: (780) 450-2111 Sales: (780) 490-2007 Fax: (780) 490-2059

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.

Notes to the table above

Three Phase Wiring Colour Codes

Notes:

The U.K. currently follows the IEC AC wiring colour codes given at I.E.C. I.E.E. ELECTRICAL WIRING COLOUR CODE CHART

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", http://mra.org.mt

www.i.e.e.org/cablecolours

Three PHase Wiring Colour Codes & Colour Changes

Three phase wiring colour codes & color changes are shown just below:

Failure to Follow Wiring Colour Code Conventions

This wiring shown below: 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).

Watch out: 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?" How dangerous is it?

Note to the table above

Regulating authority, IEC AC

Note to the table above

[1] 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

...

Continue reading at ELECTRICAL WIRING BOOKS or select a topic from the closely-related articles below, or see the complete ARTICLE INDEX.

Or see ELECTRICAL WIRING COLOR CODE FAQs - questions & answers about wire color code conventions posted originally at the end of this page.

Or see these

Recommended Articles

• ELECTRICAL DEFINITIONS, ELECTRICAL CODE BASICS
• ELECTRICAL OUTLET, HOW TO ADD & WIRE
• ELECTRICAL SPLICES, HOW TO MAKE
  • ELECTRICAL SPLICE BASICS, DEFINITIONS
  • PIGTAIL SPLICES USING TWIST-ON CONNECTORS
  • HOW TO TWIST WIRE ENDS TOGETHER
  • USE ONLY APPROVED WIRE CONNECTORS
  • TWIST ON WIRE CONNECTORS - "wire nuts"
  • SPECIAL ELECTRICAL WIRE CONNECTORS
  • TAP SPLICES
  • TAPED SPLICES
  • WIRE COLOR CODES
• ELECTRICAL SPLICE WIRING DETAILS
• ELECTRICAL WIRE TYPES CODES USES
• ELECTRICAL WIRING COLOR CODES
• SAFETY for ELECTRICAL INSPECTORS
• SE CABLE & BRANCH CIRCUIT WIRE SIZES vs AMPS

Suggested citation for this web page

ELECTRICAL WIRING COLOR CODES at InspectApedia.com - online encyclopedia of building & environmental inspection, testing, diagnosis, repair, & problem prevention advice.

Or see this

INDEX to RELATED ARTICLES: ARTICLE INDEX to ELECTRICAL INSPECTION & TESTING

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Citations & References

In addition to any citations in the article above, a full list is available on request.

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