Avoid excessive untwisting of pairs in Category 5 cable

When terminating Category 5 cable to a 110 block, installers often leave more than 1/2 inch of each wire pair untwisted. This practice is in conflict with installation recommendations included in the tia/eia-568a commercial building wiring standard.

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Roger Epperson,

Net-Comm Cabling Systems

Problem

When terminating Category 5 cable to a 110 block, installers often leave more than 1/2 inch of each wire pair untwisted. This practice is in conflict with installation recommendations included in the tia/eia-568a commercial building wiring standard.

Solution

Careful cable-stripping and termination practices will allow you to produce a clean and even termination without excessive untwisting.

Procedure

1) Cut the cable to the desired length.

2) Strip approximately 11/2 inches of the jacket off the cable.

3) Untwist all four wire pairs to the tip of the cable jacket.

4) Place the two center wires in the center positions on the 110 block, leaving 1/8 to 3/16 inch of the wire between the termination point and the tip of the cable jacket. For a T568B termination, the two center wires would be the orange and white/green ones.

5) Fan out the remaining wires to the left and to the right of the center wires.

6) Punch down all the wires in their proper positions, one at a time.

This method will give you a centered and neatly terminated cable with less than 1/2 inch of the wire untwisted.

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With the two center pairs in the center position of the 110 block, fan out the remaining two pairs.

Roger Epperson is a telecommunications technician with Net-Comm Cabling Systems (Acworth, GA).

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