Multi-pair cables (such as 25 pairs and 100 pairs) are often used in telephone systems or integrated wiring trunks, and their line sequence follows the international color spectrum standard:
1. Basic color code: a combination of primary colors (white, red, black, yellow, purple) and secondary colors (blue, orange, green, brown, and gray), for example, the first pair is white and blue, the second pair is white and orange, and the 25th pair is purple and gray.
2. Group identification: Every 25 pairs are a bundle, and the bundles are distinguished by cable ties or color rings. 100-pair cables are usually divided into 4 25-pair bundles, arranged in a counterclockwise spiral (standard ANSI/TIA-568-C.2).
3. Crimping specifications: When terminating the patch panel, a 110-type crimping tool must be used, and the line sequence is unified as T568B according to the B end (user side) to avoid crossover