25-pair color code

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Connection cable with 50 single wires or 25 double wires

The 25-pair color code , English 25-pair color code is a color coding multi-core cables in use American telephone companies for their subscriber lines twisted pair ( English twisted pair ). The color code was created with the advent of telecommunication cables with a new type of plastic insulation made of polyethylene in the 1950s at Bell Laboratories in order to mark the individual wires in a uniform color in the plastic. The marking represents an industry standard .

Each pair is defined by a main color ( English major color ) and a secondary color ( English minor color ), the set of main colors and secondary colors not overlapping. The main colors are white, red, black, yellow, purple - and the secondary colors are blue, orange, green, brown and gray. The same color was used as for the color coding on resistors .

Always two single wires carried the same combination, with one of the colors representing the basic color of the sheath and the other color being printed. Where the basic color and imprint appear changed, you have individual cores that belong together. A total of 50 single wires could be connected to 25 double wires in a cable bundle.

The Bell Laboratories developed for or a matching registered jack with 50 spring contacts, the RJ21 connector. There are therefore two ways of designating the wires - one after the twin wires (white / green) and one after the standardized connection terminal on the connector. This is comparable with the TIA-568A / B plug connections on RJ45 Ethernet cables.

25-pair color code
Twin wire Main color Secondary color
1 White blue
2 orange
3 green
4th brown
5 Gray
6th red blue
7th orange
8th green
9 brown
10 Gray
11 black blue
12 orange
13 green
14th brown
15th Gray
16 yellow blue
17th orange
18th green
19th brown
20th Gray
21st violet blue
22nd orange
23 green
24 brown
25th Gray
Standardization on the RJ21 connector
Color code
(minor / major) 		(R) (T) Color code
(main / sub) 		Corresponding connection diagram on the connector
Contact
Wire blue white stripe.svg blue / white 1 26th Wire white blue stripe.svg white / blue RJ21-female-connector.jpg
Wire orange white stripe.svg orange / white 2 27 Wire white orange stripe.svg white / orange
Wire green white stripe.svg green / white 3 28 Wire white green stripe.svg white / green
Wire brown white stripe.svg brown / white 4th 29 Wire white brown stripe.svg white / brown
Wire gray white stripe.svg slate / white 5 30th Wire white gray stripe.svg white / slate
Wire blue red stripe.svg blue / red 6th 31 Wire red blue stripe.svg red / blue
Wire orange red stripe.svg orange / red 7th 32 Wire red orange stripe.svg red / orange
Wire green red stripe.svg green / red 8th 33 Wire red green stripe.svg red / green
Wire brown red stripe.svg brown / red 9 34 Wire red brown stripe.svg red / brown
Wire gray red stripe.svg slate / red 10 35 Wire red gray stripe.svg red / slate
Wire blue black stripe.svg blue / black 11 36 Wire black blue stripe.svg black / blue
Wire orange black stripe.svg orange / black 12 37 Wire black orange stripe.svg black / orange
Wire green black stripe.svg green / black 13 38 Wire black green stripe.svg black / green
Wire brown black stripe.svg brown / black 14th 39 Wire black brown stripe.svg black / brown
Wire gray black stripe.svg slate / black 15th 40 Wire black gray stripe.svg black / slate
Wire blue yellow stripe.svg blue / yellow 16 41 Wire yellow blue stripe.svg yellow / blue
Wire orange yellow stripe.svg orange / yellow 17th 42 Wire yellow orange stripe.svg yellow / orange
Wire green yellow stripe.svg green / yellow 18th 43 Wire yellow green stripe.svg yellow / green
Wire brown yellow stripe.svg brown / yellow 19th 44 Wire yellow brown stripe.svg yellow / brown
Wire gray yellow stripe.svg slate / yellow 20th 45 Wire yellow gray stripe.svg yellow / slate
Wire blue violet stripe.svg blue / violet 21st 46 Wire violet blue stripe.svg violet / blue
Wire orange violet stripe.svg orange / purple 22nd 47 Wire violet orange stripe.svg violet / orange
Wire green violet stripe.svg green / violet 23 48 Wire violet green stripe.svg violet / green
Wire brown violet stripe.svg brown / violet 24 49 Wire violet brown stripe.svg violet / brown
Wire gray violet stripe.svg slate / violet 25th 50 Wire violet gray stripe.svg violet / slate

Individual evidence

  1. ^ American Telephone And Telegraph Company: Even PIC Cables - Bell System Practices - Section G50.607.3, Issue 2 February 1959.

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