Information Technology Reference
In-Depth Information
preinstalled mounting brackets, into which the appropriate 66M block can be
snapped. The frames may also have plastic stand-offs (sometimes called “mush-
rooms”) and brackets for cable and cross-connect wire management. Frames are
available in various sizes and can be used to implement full intermediate or main
distribution frame (IDF or MDF) facilities.
Various wiring color codes for the 66 block are shown in Fig. 7.9. The cables
are terminated on the 66 block according to these standard color codes. The 4-pair
code may be used to implement a TIA-568-C wiring system.
The overall color pattern is laid out in five “groups” of five pairs (10 wires) each.
Each group of five pairs has one primary color that is the same for all the pairs. (Note
that these are not “primary” colors, as taught in art class; rather, the term refers to the
first color in a pair of wires.) The primary colors, in order, are white, red, black, yellow,
and violet (sometimes called purple) and are commonly abbreviated W, R, BK, Y, V (or
P), although other abbreviations are sometimes used for readability, such as WHT, RED,
BLK, YEL, and VIO or PUR. The first wire group, for example, has a white wire in each
pair, along with a second wire of a different color. The secondary wire colors are blue,
orange, green, brown, and slate (sort of a silver/gray) and are abbreviated BL, O, G, BR,
and S (or sometimes BLU, ORG, GRN, BRN, and SLT). Note that TIA-568-C uses the
shortened abbreviations (the first letter of each color where there is no ambiguity and a
second letter where needed). For example, for a 4-pair cable, the color abbreviations are
W (the primary color) and BL, O, G, and BR (the secondary colors).
Each wire in a pair bears a helical or round stripe that is the same color as its
mate. The pair is referred to by its primary and secondary colors. Thus, the first pair
of the first group is the W/BL pair (said “white-blue”) and consists of a white wire
with a blue stripe and a blue wire with a white stripe. The primary-colored wire is
always punched down first (from top to bottom of the block). Thus, the top row of
the punchdown block will have a W/BL wire, the second row a BL/W wire, the third
row a W/O, and so forth.
Four-pair wires are a special case because they only use four pairs from the first
primary color group. Because of this, there is no confusion if the pairs are referred
to by their secondary color only, such as “the blue pair” or “the green pair.” Just
make sure you punch down each pair's white wire first. TIA-568-C also allows an
alternative color coding for patch cords. See Chapter 8.
Other Connecting Systems
We will mention two other connecting systems that are beginning to be used in more
and more installations. One is the NORDX/CDT (formerly Nortel Northern
Telecom) BIX system and the other is the Krone system.
