The correct modular plug facilitates crimping

Al Contarino

L-Com Inc.

Problem

Crimping modular plugs is an important and often overlooked task for the cable installer. Many varieties of modular plugs exist, however, and using the wrong type can result in open or intermittent terminations.

Solution

The first step in doing the job properly is to choose the correct plugs for your application.

Procedure

The following steps will help you purchase the plugs you need:

1) Determine whether solid- or stranded-conductor cabling will be used. Plugs intended for stranded wire have contacts that pierce into the center of the wire when crimped. Plugs for solid wire pierce through the wire insulator and then straddle the sides of the solid wire.

If stranded plugs are used with solid-conductor cable, the contact will either cut through the wire, creating an open circuitor, or go to one side of the conductor, creating an intermittent open connection. When you are not sure what type of cable you will use, buy plugs intended for solid conductors: These plugs are usually expensive, but they can be used on either solid or stranded wire.

2) Examine the outer diameter of the cable to help you determine which type of plug to choose?rectangular or round entryway. The basic rule is to use plugs with a rectangular entryway when terminating to flat telephone-type cable and use plugs with a round entryway when terminating to unshielded twisted-pair cable, which has a round jacket. A few exceptions to this rule exist, however.

For example in 10Base-T patch cords, you may need to terminate only two-pair UTP to an RJ-45 plug. The outer diameter of this cable is usually too small to make proper contact with the main strain relief of a round entryway plug; therefore, you should use a rectangular plug. Also, do not use rectangular-entryway RJ-45 plugs with four-pair UTP. This cable has a larger overall diameter, which can cause too much pressure between the main strain relief and the cable, resulting in broken wires inside the jacket.

The contacts on stranded-wire plugs pierce into the center of the wire when crimped.

Solid-wire plugs pierce through the wire insulator and then straddle the sides of the solid wire.