our CAT5 Wiring Information

our CAT5 Wiring Information
CAT5 Network Wiring information
Orange on White
White on Orange
Green on White
White on Blue
Blue on White
White on Green
Brown on White
White on Brown
Transmit +ve
Transmit –ve
Receive +ve
Receive –ve
CAT5 wiring is based on FCC modular 8 pin
connectors usually called RJ45 or 8P8C plugs.
For data rates up to 100Mbps only two pairs are used.
One pair for transmit and one pair for receive. For
correct operation each pair is twisted upon itself and
around the whole bunch in the cable at predetermined rates. It is essential therefore to keep the pairing of the connections correct
within the cable.
Each pair is marked with a pair of colours in the cable, for instance
‘Blue with a white trace’ and ‘White with a blue trace ’ called: ‘The Blue Pair’.
In some cables you will find the ‘White with a trace’ wire is actually just white so you have to
identify it by the wire it is twisted with. On cables with lots of pairs the secondary colour will
vary from white, so for instance you will get a bunch based on red, grey etc.
In a normal CAT5 connection from a HUB to a COMPUTER each pin is just wired to its
counterpart at the other end. However, sometimes it is necessary to swap the transmit and
receive pair over, for instance to connect a COMPUTER to a COMPUTER, or a HUB to a
HUB. This type of connection is called a ‘crossover’. Some HUBs can detect the need for a
crossover automatically. Alternatively you can use a ‘crossover adapter’ or make up a
special cable. However, it would be unwise to do the crossover in a wall socket as this
would deviate from the standard.
Un-used pins can be used for other applications such as your telephone or ISDN
connections. However if you do use pairs for such things be sure they are not also
connected into your CAT5 devices as it cannot be assumed they are not internally grounded
or similar. Be aware also that these connections may be used for power-over-ethernet
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