The wiring standard used in CAT 5 cabling originates with
AT&T, and uses the Bell System color code to identify wire
pairs. This color scheme identifies the pair numbers, and
conductor polarity, and applies to the WIRE, not the connec-
tor. It is important to know which pairs are which, and the
function of the pins on the RJ-45 connector.
The colors are BLUE, ORANGE, GREEN and BROWN for
the first four pairs. The color code extends well beyond that,
but since we are only dealing with four pairs of wire, you
don’t need to know the entire Bell System color code for ter-
minating a 900 pair distribution trunk! What is often con-
fusing is that the pair numbers do not line up with the pin
numbers on the RJ-45 connector. In other words, conductor
1 of the cable (White w/Blue Strip) is NOT terminated to
PIN ONE of the connector. The AT&T connecting standard
always uses the middle pins for the first pair. After that, they
are staggered around, primarily to prevent crosstalk between
adjacent pairs. It is very important that you build the cable
with ALL PAIRS properly terminated. This will prevent any
confusion later, and give your cable a solid mechanical con-
nection.
In accordance with the AT&T standard, there is a positive
and negative conductor for each pair, indicated by the color
code. In Bell parlance, positive is labeled as the “Tip”, and
negative as the “Ring”. It is important to know this, since a
lot of documentation on the subject still uses this terminolo-
gy.
Notice on the chart that the order of the wire pairs does not
follow the connector pins, as mentioned earlier. Don’t let
that confuse you. The first wire of a given pair is always the
white wire with a colored stripe and is the positive (Tip)
conductor. The corresponding colored wire with the white
stripe is the negative (Ring) conductor for that pair.
If you follow these standards for building your own CAT 5
cables, you should have no problems. Get yourself a high
quality crimping tool, an inventory of RJ-45 connectors and
stock up on CAT 5 wire.
CAT 5 Cables
Page 41
Peavey Electronics Corporation
CAT 5 Cabling & Terminations
Pins (1-8)
Conductors
RJ-45 Shell
Jacketed Cable
Fig. 9, Standard CAT 5 cable
Fig. 11, CAT 5 cable and RJ-45 termination details
Fig. 10, CAT 5 Wire/Connector cross reference chart
White w/blue stripe
Blue w/white stripe
White w/orange stripe
Orange w/white stripe
White w/green stripe
Green w/white stripe
White w/brown stripe
Brown w/white stripe
Conductor
1
1
2
2
3
3
4
4
Wire Pair
5
4
1
2
3
6
7
8
Connector Pin
Blue Pair
Orange Pair
Green Pair
Brown Pair
Pin 1
Pin 8
Pin 8
Pin 1
Blue Pair
Brown Pair
Green Pair
Orange Pair
