Internal Cable Colour Code

The 25-pair colour code explained: tip, ring, major and minor colours

The 25-pair colour code is the foundation of all twisted-pair telecommunications and data cabling. It uses two groups of five colours to identify 25 unique conductor pairs, and the same system scales up through binder groups to identify up to 600 pairs in larger cables. Understanding the logic behind tip, ring, major and minor colours is the key to terminating any multi-pair cable correctly.

This guide focuses on how the colour code system works. For the full multi-pair reference including binder sequences for 50, 75 and 100 pair cables, see our Multi-pair telephone cable colour code guide. For pinouts on common plugs and sockets, see our Internal cable pair assignment guide.

Why two colours per conductor?

Every conductor in a twisted-pair cable carries two colours: a primary base colour and a secondary band or stripe. This two-colour system is what allows 25 unique pairs to be identified from just ten ink colours. Without the band, you would need 50 separate solid colours to identify all 50 conductors in a 25-pair cable, which is impractical.

The two-colour combination also identifies which conductor is the tip and which is the ring in each pair. The tip wire shows the major colour first, with a minor colour band. The ring wire shows the minor colour first, with a major colour band. Pair 1 has a tip of White with a Blue band, and a ring of Blue with a White band.

Major colours (tip group)

Five major colours identify which group of 5 pairs you are looking at:

  • White: pairs 1 to 5
  • Red: pairs 6 to 10
  • Black: pairs 11 to 15
  • Yellow: pairs 16 to 20
  • Violet: pairs 21 to 25

The major colour is sometimes called the primary colour, the tip colour, or the "major" because it appears as the base colour of the tip conductor in each pair.

Minor colours (ring group)

Five minor colours identify the position of each pair within its group:

  • Blue: pair 1 within each group
  • Orange: pair 2 within each group
  • Green: pair 3 within each group
  • Brown: pair 4 within each group
  • Slate: pair 5 within each group

The minor colour is sometimes called the secondary colour, the ring colour, or simply the "minor". It appears as the base colour of the ring conductor in each pair.

What is tip and ring?

"Tip" and "ring" are the two conductors that make up a single telephone or communications pair. The terms date back to the manual telephone switchboards of the early 20th century, where each connection was made with a three-conductor plug. The connection at the very tip of the plug was the positive (tip) wire, the connection at a ring around the plug body was the negative (ring) wire, and the sleeve provided the ground.

The names stuck even as the hardware evolved. Today, "tip" and "ring" simply identify the two sides of a single twisted pair. In the 25-pair colour code, the tip conductor carries the major colour and the ring conductor carries the minor colour, each with the opposite colour as its band.

How to read a pair in the field

To identify any pair in a multi-pair cable:

  1. Look at the base (solid) colour of each conductor. One will be a major colour (White, Red, Black, Yellow or Violet), the other will be a minor colour (Blue, Orange, Green, Brown or Slate).
  2. The conductor with the major base colour is the tip. The conductor with the minor base colour is the ring.
  3. The major colour tells you which group of 5 pairs you are in (White is pairs 1 to 5, Red is 6 to 10, etc).
  4. The minor colour tells you the position within that group (Blue is position 1, Orange position 2, etc).
  5. Combine the two for the pair number. White/Blue is pair 1. Yellow/Green is pair 18. Violet/Slate is pair 25.

25-pair colour code reference table

Pair Tip (major + minor band) Ring (minor + major band)
1 White/Blue Blue/White
2 White/Orange Orange/White
3 White/Green Green/White
4 White/Brown Brown/White
5 White/Slate Slate/White
6 Red/Blue Blue/Red
7 Red/Orange Orange/Red
8 Red/Green Green/Red
9 Red/Brown Brown/Red
10 Red/Slate Slate/Red
11 Black/Blue Blue/Black
12 Black/Orange Orange/Black
13 Black/Green Green/Black
14 Black/Brown Brown/Black
15 Black/Slate Slate/Black
16 Yellow/Blue Blue/Yellow
17 Yellow/Orange Orange/Yellow
18 Yellow/Green Green/Yellow
19 Yellow/Brown Brown/Yellow
20 Yellow/Slate Slate/Yellow
21 Violet/Blue Blue/Violet
22 Violet/Orange Orange/Violet
23 Violet/Green Green/Violet
24 Violet/Brown Brown/Violet
25 Violet/Slate Slate/Violet

Frequently asked questions

What does the 25-pair colour code mean by major and minor colours?

Major colours are the five tip colours (White, Red, Black, Yellow, Violet) that identify which group of 5 pairs you are in. Minor colours are the five ring colours (Blue, Orange, Green, Brown, Slate) that identify the position of the pair within its group. Combining one major with one minor gives 25 unique pair identifications.

What are the five major (primary) colours in the 25-pair colour code?

White, Red, Black, Yellow and Violet. They appear in this order: White covers pairs 1 to 5, Red covers 6 to 10, Black covers 11 to 15, Yellow covers 16 to 20, and Violet covers 21 to 25.

What are the five minor (secondary) colours in the 25-pair colour code?

Blue, Orange, Green, Brown and Slate. These five colours always appear in this order within each group of 5 pairs. Blue is the first position, Orange the second, Green the third, Brown the fourth, and Slate the fifth.

What is the difference between tip and ring in telephone wiring?

Tip and ring are the two conductors of a single telephone pair. The tip wire carries the major colour as its base and the minor colour as a band. The ring wire is the reverse: minor colour base, major colour band. The names come from the original telephone switchboard plugs, where one connection was at the tip of the plug and the other at a ring around it.

How do I know which wire is the tip and which is the ring?

Look at the base (solid) colour of each conductor. The wire with a major colour base (White, Red, Black, Yellow or Violet) is the tip. The wire with a minor colour base (Blue, Orange, Green, Brown or Slate) is the ring. The opposite colour appears as a band or stripe.

Does the same 25-pair colour code work for cables larger than 25 pairs?

Yes. In cables of 50 pairs or more, the same 25-pair colour code is used within each 25-pair sub-unit, and each sub-unit is wrapped with a coloured binder thread that follows the same major/minor sequence. See our multi-pair telephone cable colour code guide for full binder sequences.


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