25-pair color code
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25_pair_color_code_chart.png
25 Pair Color Code Chart
The 25 pair color code is a color code used to identify individual conductors in a kind of electrical communication wiring known as twisted pair cables. The colors are applied to the insulation that covers each conductor. The first color is chosen from one group of five colors and the other from a second group of five colors, giving 25 combinations of two colors.
The first group of colors is, in order: white, red, black, yellow, violet.
The second group of colors is, in order: blue, orange, green, brown, slate.
(The color violet is more commonly called purple, but in the telecommunications and electronics industry it is always referred to as violet. Similarly, slate is a particular shade of gray. The names of most of the colors were taken from the conventional colors of the rainbow or optical spectrum, and in the Electronic color code, which uses the same 10 colors, red through violet are also in spectral order, 2-7.)
One of the most common uses of the codes is in Category 5 computer network wiring, as used for structured cabling for switched Ethernet installations, where only the codes for the first four pairs are used.
Sometimes each wire in a pair will have a colored stripe matching the color of its paired wire. This makes it easy to identify which pair a given wire belongs to. Otherwise, to determine which pair a wire belongs to one has to note which color codes are physically twisted together.
| Pair # | First wire | Second wire |
|---|---|---|
| 1 | White | Blue |
| 2 | White | Orange |
| 3 | White | Green |
| 4 | White | Brown |
| 5 | White | Slate |
| 6 | Red | Blue |
| 7 | Red | Orange |
| 8 | Red | Green |
| 9 | Red | Brown |
| 10 | Red | Slate |
| 11 | Black | Blue |
| 12 | Black | Orange |
| 13 | Black | Green |
| 14 | Black | Brown |
| 15 | Black | Slate |
| 16 | Yellow | Blue |
| 17 | Yellow | Orange |
| 18 | Yellow | Green |
| 19 | Yellow | Brown |
| 20 | Yellow | Slate |
| 21 | Violet | Blue |
| 22 | Violet | Orange |
| 23 | Violet | Green |
| 24 | Violet | Brown |
| 25 | Violet | Slate |
When used for common analog telephone service, the first wire is known as Tip and is connected to Ground, the positive side of the direct current DC circuit, while the second wire is known as Ring and is connected to the negative side of the circuit.
These terms are based on the 1/4" phono plug where the "tip" of the connector is seperated from the "ring" of the connector with a ring of insulation, with the longer peice of the connector being referred too as the "ring" side of the connector. The "female" side or "jack" end is normally wired with the "tip" and "ring" configuration also, to accomadate the "plug" and maintain correct polarity when connections are established.
For cables with over 25 pairs, the first 25 pairs (called a binder group) are marked with a White/Blue ribbon, the second 25 pairs with a White/Orange ribbon, and so on through the 25th binder group (625 pairs), which has a Violet/Slate ribbon. The pattern then starts over with White/Blue, and continues indefinitely.