Backbone-cable punchdowns made easy

Bernard J. Sinkiewicz, Rutgers University

Problem

When you are punching down unshielded twisted-pair backbone cables that contain between 100 and 300 pairs, accessing the rear of the punchdown blocks can be a nightmare because the blocks sit so close to the wall.

Solution

Avoid reaching behind a block by placing the backbone cables, stripping their outer jackets, and separating the pairs before you mount the block onto the wall. The process requires a couple of extra steps initially, but ultimately saves a lot of time and aggravation.

Procedure

1) Fasten the backbone cables to the wall.

2) Measure the cables on the wall and, for each one, strip the jacket at the point at which the connecting block will be mounted to the wall.

3) Separate the wire pairs into groups. For example, separate a 100-pair cable into four separate 25-pair bundles.

4) Tape the end of each bundle and fan the bundles out from the cable.

5) Mount the block to the wall, feeding each bundle through the legs at the appropriate places so the pairs can be terminated onto the block.

6) As you punch down the pairs, take the tape off one bundle at a time so all the unterminated wire pairs are still neatly organized.

In this illustration, three 100-pair cables have each been stripped at the appropriate point on the wall and the wires have been separated into 25-pair bundles.

Feeding the taped bundles through the legs of the connecting block when installing the block on the wall allows you to keep the wire pairs in order as you are punching them down.

Bernard J. Sinkiewicz is an electronics technician at Rutgers University`s New Brunswick, NJ, facility. This tip was submitted for the Cabling Installer Tips` Contest at Cabling Installation Expo `98, held last October in Atlanta, GA.