On 8 Dec 2003 at 2:20, Lee Jones wrote: > > Telephone standard practice has used the same color code for > at least 25 years (that I've been working with it). It is an > extensible standard that goes up to (at least) 625 pairs. I > think it goes beyond that, but I've never worked with a cable > larger than 600 pairs (or even nearly that big). > > There are 5 wire colors -- blue (bl), orange (or), green (gr), > brown (br), & slate (sl) -- and 5 group colors -- white (wh), > red (rd), black (bk), yellow (yl), & violet (vi). mnemonic crutch - got it from a Texan. A city guy might replace Varmint with Vermin. Boys On Girls Brings Sex wire Why Run Backwards You Varmint group Mike > > 25-pair is the primary unit. Each pair is identified by the > combination of a group color plus a wire color. For example, > the 1st pair is white/blue (wh/bl), 2nd pair is white/orange > (wh/or), ... 5th pair is white/slate (wh/sl), 6th pair is > red/blue (rd/bl), ... & 25th pair is violet/slate (vi/sl). > > If a cable has more than 25 pairs in it, each 25 pair bundle > is held together with a colored binder over-wrap. The binder > is the group color (or group+wire) color. First 25 pairs use > a white (or white-blue) binder. Second 25 pairs use a red > (or white-orange) binder. You can easily extend this up to > 625 pairs (25 bundles of 25 pairs). > > For example, a 100 pair cable will have 4 bundles of 25 pairs. > First bundle will usually be wrapped in white+blue nylon binder. > Second bundle is in white+orange binder. Third bundle is in a > white+green binder. Fourth bundle is in a white+brown binder. > > > Old cables had solid color wires. The first pair was a solid > white wire twisted with a solid blue wire. You never untwisted > a pair until you were ready to punch it down because you lost > the "pairing". > > New cables (last 20 years or so) have each wire more uniquely > marked. Each has a primary color with a spiral marker color. > The first wire of first pair is mostly white with a blue spiral. > Second wire is mostly blue with a white spiral. Much nicer to > work with since you can untwist and fan out an entire cable > without losing information. > > [ Practical note: tiny spirals of orange and brown look an > awful lot alike in a dimly lit, dusty telco closet. Have > a bright flashlight or a work light handy. :-) ] > > > To identify individual wires, the group color wire is first. > 1st wire of 25 pr bundle is white wire of white/blue (1st) pair. > 2nd wire of 25 pr bundle is blue wire of white/blue (1st) pair. > 13th wire of 25 pr bundle is red wire of red/orange (7th) pair. > 14th wire of 25 pr bundle is orange wire of red/orange (7th) pair. > 50th wire of 25 pr bundle is slate wire of violet/slate (25th) pair. > Individual wires are almost NEVER used -- use is _always_ in pairs. > > Normally, 25 pair cable is terminated on a punch-down block; > either 66B style (6 position wide x 50 wire long), 66M block > (4 position wide x 50 wire long), or 110 block (various types). > > Usually, a 66M block is vertically oriented. Commonly each > 66M block in a telco closet or central office, containing 25 > pair (50 wires), is punched up as follows from top to bottom: > > 1 white/blue wh/bl > blue/white bl/wh > 2 white/orange wh/or > orange/white or/wh > 3 white/green wh/gr > green/white gr/wh > 4 white/brown wh/br > brown/white br/wh > 5 white/slate wh/sl > slate/white sl/wh > 6 red/blue rd/bl > blue/red bl/rd > 7 red/orange rd/or > orange/red or/rd > 8 red/green rd/gr > green/red gr/rd > 9 red/brown rd/br > brown/red br/rd > 10 red/slate rd/sl > slate/red sl/rd > 11 black/blue bk/bl > blue/black bl/bk > 12 black/orange bk/or > orange/black or/bk > 13 black/green bk/gr > green/black gr/bk > 14 black/brown bk/br > brown/black br/bk > 15 black/slate bk/sl > slate/black sl/bk > 16 yellow/blue yl/bl > blue/yellow bl/yl > 17 yellow/orange yl/or > orange/yellow or/yl > 18 yellow/green yl/gr > green/yellow gr/yl > 19 yellow/brown yl/br > brown/yellow br/yl > 20 yellow/slate yl/sl > slate/yellow sl/yl > 21 violet/blue vi/bl > blue/violet bl/vi > 22 violet/orange vi/or > orange/violet or/vi > 23 violet/green vi/gr > green/violet gr/vi > 24 violet/brown vi/br > brown/violet br/vi > 25 violet/slate vi/sl > slate/violet sl/vi > > The binder over-wrap, cut off during the punch-down process, is > frequently tied around one of the top corners of each 25 pair > block to identifiy each bundle in a 50 or 100 pair cable. > > > 25 pair cables used to be quite common in offices when each desk > phone was a 1A2 key system multi-button phone. This took a 25 pair > cable going from the telco closet out to each desk! Now, the desk > phone signalling is all digital on 1 or 2 pairs. The 25-, 50-, and > 100-pair cables are only used between distribution frames, between > floors, and on backhauls to the central office. > > Notice that normal 4 pair UTP cable used for Ethernet shows it's > telephone company heritage because it follows the color code of > the first four pairs as listed above. > > Lee Jones > > -- > http://www.piclist.com hint: PICList Posts must start with ONE topic: > [PIC]:,[SX]:,[AVR]: ->uP ONLY! [EE]:,[OT]: ->Other [BUY]:,[AD]: ->Ads -- http://www.piclist.com hint: PICList Posts must start with ONE topic: [PIC]:,[SX]:,[AVR]: ->uP ONLY! [EE]:,[OT]: ->Other [BUY]:,[AD]: ->Ads