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cable in an installation that otherwise uses 3-pair cables), then simply cut the extra
pairs flush at the point where the cable jacket was removed. You may be able to pull
the jacket back slightly before you cut off the excess pairs. Then push the jacket
back in place to make a neat installation.
The 66M block is designed to terminate unskinned solid copper conductors with
plastic insulation. Conductors from AWG 20 to 26 can be accommodated. The use of
stranded wire is not recommended under any circumstances. To terminate a wire, the
wire is pressed down into the slot between the fingers of the contact with a punch-
down impact tool, shown in Fig. 7.7. The tool causes the insulation to be displaced,
leaving the copper wire and phosphorous-bronze clip in direct, gas-tight contact.
The spring action of the tin-plated contact holds the wire in place. The tool
also trims off the excess wire after termination. Only one conductor may be termi-
nated in each contact slot. If a wire is removed from a contact slot, the slot may be
reused, but only if the new wire is the same or larger size. Using a smaller wire, using
a slot repeatedly, or punching two wires into a slot will cause the connection to fail,
sooner or later.
As we have said, station wires are punched down from both sides of the block.
Because the block has 48 usable row positions, that means that you can terminate
six station cables per side of the block, or a total of 12 cables per block, assuming
4-pair cables. On a standard (nonconnectorized) 66M block, you should punch
down the station wires on the outer contact of each dual pronged clip. (Some con-
nectorized blocks wire to the outer contacts, instead of using a wire-wrap clip.)
FIGURE 7.7
To terminate a wire, the wire is pressed down into the slot between the fingers of the 66-
block contact with a punchdown tool. The optional 110 blade is also shown. (Courtesy of The
Siemon Company.)
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