Information Technology Reference
In-Depth Information
Insert wire between washers
(clockwise wrap)
Insert spade lug below washers
(above post)
FIGURE 6.10
Proper wire termination for screw terminals.
wire should be trimmed after the screw is tightened. It is also a good idea for LAN
circuits to try to maintain as much of the pair twist as possible, up to the point of
termination. Some authorities recommend trying to limit the untwist of Category 3
cable to no more than 1.5 to 2 in.
The other type of wire termination is the IDC contact. This contact avoids
stripping the insulation manually, by cutting through the insulation during the ter-
mination process. The wire, cut to length, is inserted into the contact area and
snapped into place, either by a special tool or by snapping a plastic cap onto the
IDC contact. Either action causes a small area of insulation to be pierced and elec-
trical connection made with the underlying contact. There are three common types
of IDC contact mechanisms: the 66 type, the 110 type, and the snap-in type. Other
proprietary mechanisms include BIX and Krone types.
An older type of IDC jack contact field is fashioned from a shortened version
of the traditional 66-type punchdown block. In this jack type, the wires of the mod-
ular connector are connected to positions on the block into which wires from the
station cable are punched. The amount of untwisted wire from the block to the con-
nector is usually too great for this type of jack to be certified above Category 4, if
indeed it is certified at all.
Another type of IDC jack contact incorporates the newer 110-type punchdown
strip as shown in Fig. 6.11. The 110 strip may be separate from the modular con-
nector and connected by wires, as with the 66-type jacks, or it may be an integral
part of the connector module. If discrete wires connect the strip, the same
untwisted-wire problem exists as with the 66 blocks, and certification above
Category 3 or 4 is rare. However, if this block is incorporated into the connector
