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Figure 2-17.—Aluminum terminal lug and splice | Up
Neets Module 04-Introduction to Electrical Conductors, Wiring Techniques, and Schematic Reading | Next
Table 2-2.—Color Coding of Copper Terminal Lug or Splice Insulation |
2-18
1. Carefully remove the conductor insulation. Do not cut or nick the aluminum conductors. Do not
wire-brush or scrape the aluminum conductor (the compound in the terminal or splice barrel will
clean it satisfactorily).
2. Remove the protective foil wrapping from the terminal or splice and check the amount of
compound in the terminal barrel. It should be one-fourth to one-half full.
3. Slip the spaghetti or heat-shrinkable tubing over the wire and back far enough to be out of the
way of the crimping operation. Insert the stripped conductor the full length of the terminal or
splice barrel. While doing this, leave the plug over the inspection hole. This allows the
compound to be forced in and around the strands.
4. Center the terminal lug or splice in the crimping tool.
5. Actuate the power crimping tool.
6. Wipe off the excess compound. Inspect the joint with a probe through the inspection hole. The
end of the conductor should come to the edge of the inspection hole.
7. Slip the tubular insulation down over the terminal or splice barrel. Tie it in place if spaghetti is
used. If using heat-shrinkable tubing, shrink with a heat gun.
Q15.
Should aluminum wire be cleaned prior to installing an aluminum terminal lug or splice?
Q16.
What tools should be used to install large aluminum terminal lugs and splices?
Q17.
Why should a lockwasher never be used with an aluminum terminal?
Improper crimping procedures eventually cause terminal failure. Be especially careful of
undercrimping, overcrimping, using wrong crimping tools, improper cleaning methods, and cutting or
nicking the conductors. A loose contact allows an oxide film to form between the wire and the terminal.
This results in increased resistance, and the resistance causes heat. The heat accelerates deterioration, and
eventually a failure results.
PREINSULATED COPPER TERMINAL LUGS AND SPLICES
The use of preinsulated terminal lugs and splices has become the most common method for copper
wire termination and splicing in recent years. It is by far the best and easiest method. There are many
tools used for crimping terminal lugs and splices.
Hand, portable power, and stationary power tools are available for crimping terminal lugs. These
tools crimp the barrel to the conductor and, at the same time, form the insulation support to the wire
insulation.
The power tools, both stationary and portable, are usually found in large shops where wire bundles
are made up. In the next paragraphs, we will discuss the more common hand-crimping tools you will most
likely be using in your day-to-day work.
TERMINATING COPPER WIRE WITH PREINSULATED TERMINAL LUGS
Small-diameter copper wires are terminated with solderless, preinsulated copper terminal lugs. As
shown in figure 2-19, the insulation is part of the terminal lug. It extends beyond the barrel so that it
covers a portion of the wire insulation. This makes the use of spaghetti or heat-shrinkable tubing
unnecessary. Preinsulated terminal lugs also have an insulation support (a metal reinforcing sleeve)
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