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Wiring color codes used for electrical wiring has a specific meaning with different colors for different types and purposes of circuits. Electricians and contractors understand these codes. For those who want to learn, a simple guide can help to understand their meaning . This post will discuss what are Wiring Color Codes, regional wiring color codes in USA, UK, Europe & Canada and when should we apply these codes.

What are Wiring Color Codes

Each color used for electrical wiring tells us the type and purpose of the wire. It’s a standardization which is followed in regions for better understanding and trace-ability. In some countries, the applicable governing body specifies all permissible wiring colors, but in others only a few specific types of wiring are required to have specific colors.

Therefore, the significance of any given wire color may vary from country to country. But here is a useful guide to the significance of different colors used in different parts of the world for common types of AC (alternating current) electrical wiring.

Wiring Color Codes

Fig. 1 – Wiring Color Codes

Wiring Color Codes in United States of America (USA)

American electrical contractors and electricians must comply with the National Electrical Code (NEC) for the color coding of wires. These are typically used for power wires in “branch circuits”.

NEC defines White or Grey color for neutral wire and green/ green with yellow stripe/ bare copper for ground wire. Any other colors except these may be used for other power lines. However, as per local practice, the standard wiring color codes may be divided in two main categories. They are:

  • USA Wire Color Codes for AC Supply
  • USA Wire Color Codes for DC Supply

USA Wiring Color Codes for AC Supply

The wire color codes followed in USA for AC Supply may be categorized in three sub-categories depending on the nature and range of AC supply. They are:

  • 120/208/240 Volt AC Wire Color Codes
  • 277/480 Volt AC Wire Color Codes
  • DC Supply Wire Color Codes

120/208/240 Volt AC Wiring Color Codes in USA

These AC ranges are mostly used in home and office environment. The wire color codes for this category is as follows:

  • Single Phase, Line (Hot) – Black or Red
  • 3 Phase, Phase 1 – Black
  • 3 Phase, Phase 2 – Red
  • 3 Phase, Phase 3 – Blue
  • Neutral – White
  • Ground – Green, Green with Yellow Stripe, or Bare Wire

120 208 240 Volt AC Wiring Color Codes in USA

Fig. 2 – 120/208/240 Volt AC Wiring Color Codes in USA

277/480 Volt AC Wiring Color Codes in USA

These are commonly seen in industrial motors and equipment’s. The color codes are:

  • 3 Phase, Phase 1 – Brown
  • 3 Phase, Phase 2 – Orange
  • 3 Phase, Phase 3 – Yellow
  • Neutral – Gray
  • Ground – Green, Green with Yellow Stripe, or Bare Wire

277 480 Volt AC Wiring Color Codes in USA

Fig. 3 – 277/480 Volt AC Wiring Color Codes in USA

USA Wiring Color Codes for DC Supply

Solar power systems and many battery systems use DC power instead of AC power (alternating current). NEC of USA defines green/ green with yellow stripe/ bare copper for ground wire. Any other colors except these may be used for other power lines. However, as per local practice, the standard wire color codes are as follows:

2 Wire Ungrounded DC Supply

  • Positive (+ve) – Red
  • Negative (-ve) – Black

2 Wire Grounded DC Supply

  • Positive (+ve) of Negative (-ve) grounded circuit – Red
  • Negative (-ve) of Negative (-ve) grounded circuit – White
  • Positive (+ve) of Positive (+ve) grounded circuit – White
  • Negative (-ve) of Positive (+ve) grounded circuit – Black

3 Wire Grounded DC Supply

  • Positive (+ve) – Red
  • Mid Wire (Centre Tap) – White
  • Negative (-ve) – Black

Common

Ground – Green, Green with Yellow Stripe, or Bare Wire

DC Power Wiring Color Codes in USA

Fig. 4 – DC Power Wiring Color Codes in USA

Wiring Color Codes in Europe including UK (IEC)

Most European countries, including the United Kingdom, are now following the color conventions for AC branch circuits laid down by the International Electro-technical Commission (IEC). Most European countries follow a wire color code established by IEC. Originally published as IEC 60446, this standard was incorporated into IEC 60445 in 2010. The Wiring color codes as per IEC may be divided in following two categories:

  • Wire Color Codes in Europe (IEC) for AC Supply
  • Wire Color Codes in Europe (IEC) for DC Supply

Wiring Color Codes in Europe (IEC) for AC Supply

Wire Color Codes in Europe (IEC) for AC supply are as follows:

  • Single Phase, Line (Hot) – Brown
  • 3 Phase, Line 1 – Brown
  • 3 Phase, Line 2 – Black
  • 3 Phase, Line 3 – Grey
  • Neutral – Blue
  • Ground – Green with Yellow Stripe

AC Supply Wiring Color Codes in Europe (IEC)

Fig. 5 – AC Supply Wiring Color Codes in Europe (IEC)

Wiring Color Codes in Europe (IEC) for DC Supply

European (IEC) Wire Color Codes for DC Supply are as follows:

2 Wire Ungrounded DC Supply

  • Positive (+ve) – Brown
  • Negative (-ve) – Grey

2 Wire Grounded DC Supply

  • Positive (+ve) of Negative (-ve) grounded circuit – Brown
  • Negative (-ve) of Negative (-ve) grounded circuit – Blue
  • Positive (+ve) of Positive (+ve) grounded circuit – Blue
  • Negative (-ve) of Positive (+ve) grounded circuit – Grey

3 Wire Grounded DC Supply

  • Positive (+ve) – Brown
  • Mid Wire (Centre Tap) – Blue
  • Negative (-ve) – Grey

Common

Ground – Green with Yellow Stripe

DC Power Wiring Color Codes in Europe (IEC)

Fig. 6 – Wiring Color Codes in Europe (IEC) for DC Supply

Wiring Color Codes in Canada

The Canadian Electrical Code (CEC) regulates electrical wiring color coding in Canada. The AC power cable color code is nearly similar to the code used in the USA except exclusion of bare copper from ground wire. The following requirements on wire color codes apply in Canada:

  • Single Phase, Line (Hot) – Black or Red
  • 3 Phase, Phase 1 – Red
  • 3 Phase, Phase 2 – Black
  • 3 Phase, Phase 3 – Blue
  • Neutral – White
  • Ground – Green or Green with Yellow Stripe

AC Wiring Color Codes in Canada

Fig. 7 – Wiring Color Codes in Canada

When to Apply Wiring Color Codes to Wire

Most narrow wires are color-coded by the manufacturer using different color insulation. If the cables are larger than #6 AWG, they are usually covered with black insulation. During installation, color coding should be added using colored insulation tapes by wrapping it around the wire. The other way to do this is by using labels or colored heat shrink tubes.