17.1 Wiring Layout

    ......Wiring Closet..............                ....User Work Area....
    [HUB]<=====>[PANEL]+=====+[BLOCK]+==============+[WALL]<=====>[STATION]

    Where ...
   HUB = concentrator
   PANEL = RJ-45 Modular Patch Panel

   BLOCK = Telco Splice Block (Typically 25-pair)

   Crossconnect: NorTel BIX1A, AT&T 110 and similar crossconnect 
   blocks accommodate 4-pair, 25-pair or larger cables on the 
   same mount. The same type of mount can be used for the voice 
   field as well as data.
  
   Telephone-only (66) blocks are seldom used except for 
   low-speed data circuits such as are used for IBM 3270 terminals. 
   The newer types of crossconnect mentioned above cost about the 
   same and accommodates growth much better. (The standard AT&T 110 
   and its BIX equivalent are rated at Cat 5).

   LOBE CABLE = Cable run from user wall plate to wiring closet
   WALL = User area wall face plate
   STATION = User workstation network adapter
   =====>  = RJ-45 connector
   =====+  = Punch down termination (also called an insulation-
      displacement/displacing connector, or IDC).

     17.2 Crossconnect Field Colors
     The color of label used on a crossconnect field identifies the
     field's function. The cabling administration standard (CSA T-528
     & EIA-606) lists the colors and functions as:

   Blue  Horizontal voice cables
   Brown  Interbuilding backbone
   Gray  Second-level backbone
   Green  Network connections & auxiliary circuits
   Orange Demarcation point, telephone cable from Central Office
   Purple  First-level backbone
   Red  Key-type telephone systems
   Silver or
   White  Horizontal data cables, computer & PBX equipment
   Yellow Auxiliary, maintenance & security alarms