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DC Power Circuit Wiring Color Codes

DC Power Circuit Wiring Color Codes

 Many computer systems, solar power systems, electronics, automotive applications, and telecommunications systems run off of DC (Direct Current) power supply. Color coding for DC power circuit wiring depends on the function and the location (country) of the wiring. In our last article, we discussed International Color Coding for AC Power Circuits. In this article, you’ll find a guide for international wire color coding of DC power circuits.  

Who regulates color coding for DC circuits?

Most countries have a governing organization that implements color coding requirements for electrical wiring. In cases where there are no legal requirements, specific colors have been adopted as local practice and are recommended. 

NEC (National Electrical Code)

In the United States, the National Electrical Code (NEC) mandates electrical wiring color codes for the protective ground. The protective ground must be either green, green-yellow, or bare copper. “Green-yellow” refers to green with yellow stripes. For all other functions, there are no legal requirements. However, certain colors have been adopted as local practice and are recommended. Due to safety reasons, the use of a 2-wire ungrounded system is discouraged. However, the colors red (for positive) and black (for negative) follow the grounded system coloring code.  

2-Wire Ungrounded DC: (Not recommended due to safety)

  • Positive (labeled as “L+”): Red?
  • Negative (labeled as “L-“): Black?
2-Wire Grounded (of a Negative Grounded) DC Circuit:
  • Positive (labeled as “L+”): Red*
  • Negative (labeled as “N“): White*
2-Wire Grounded (of a Positive Grounded) DC Circuit:
  • Positive (labeled as “N”): White*
  • Negative (labeled as “L-“): Black*
3-Wire Grounded DC:
  • Positive (labeled as “L+”): Red*
  • Mid-Wire/Center Tap (labeled as “N”): White*
  • Negative (labeled as “L-“): Black*
Protective Ground:
  • (labeled as “PG”): Green, Green-Yellow, or Bare Copper

? Although their use is discouraged for safety, these colors follow the coloring code for grounded systems.

* These colors are not required by the NEC, but have been adopted as local practice.   

IEC (International Electrotechnical Commission)

Throughout most of Europe and in the United Kingdom (UK), the International Electrotechnical Commission mandates electrical wiring color codes for all functions.  

2-Wire Unearthed DC:

  • Positive (labeled as “L+”): Brown
  • Negative (labeled as “L-“): Grey
2-Wire Earthed (of a Negative Earthed) DC Circuit:
  • Positive (labeled as “L+”): Brown
  • Negative (labeled as “M“): Blue
2-Wire Earthed (of a Positive Grounded) DC Circuit:
  • Positive (labeled as “M”): Blue
  • Negative (labeled as “L-“): Grey
3-Wire Earthed DC:
  • Positive (labeled as “L+”): Brown
  • Mid-Wire (labeled as “M”): Blue
  • Negative (labeled as “L-“): Grey
Protective Earth:
  • (labeled as “PE”): Green-Yellow

  For a more visual way to show the international wiring color codes for DC power, we’ve created this ‘DC Power Circuit Wiring Color Codes’ infographic.

Feel free to print it out as a quick reference guide! As always if you have any questions about wire labels or markers, feel free to contact us at info@ziptape.com or (480) 966-2999.   

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