Cabletron Systems 100BASE-FX, Cabling Manual

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Cabling Devices
13-6 Cable Termination
Punchdown Block
A punchdown block is another means of attaching raw strands of facility cable to
a single jumper cable. The punchdown block allows the actual metal strands of
facility UTP cable to be punched down, using a special tool, onto bayonet pins.
These bayonet pins are connected to one another through the punchdown block’s
internal wiring. Most punchdown blocks wire the leftmost column of pins to the
left inside column, and the rightmost column of pins to the inside right column.
Punchdown blocks are also available which provide a prewired 50-pin RJ21
connector for connection to 25-pair facility UTP.
Punchdown blocks are commonly used in the same way patch panels are. They
provide an access point for connecting and repairing cables. The exposed,
conductive bayonet pins provide an easily accessible testing point for checking
the operation of a cable after installation.
Punchdown blocks are often identified by a model number. A very common type
of punchdown block is the AT&T 66 block.
Figure 13-5. AT&T 66 Punchdown Block
Mounting
Bracket
(detail)
"Bayonet" pins
Punchdown
Tool
1845n33