Introduction to Wiring Techniques
A. Bhatia, B.E.
The satisfactory performance and continuous reliability of electrical system greatly depends on the quality of wiring. Improperly or carelessly installed wiring systems can be potentially dangerous and may result in electrocution and fire. This course will assist you in learning the basic skills of proper wiring techniques. It explains the different ways to terminate and splice electrical conductors. It also discusses various soldering techniques and many of the techniques used to cut, strip and crimp the wire. The course ends with a discussion of the procedure to be followed when you lace wire bundles within electrical and electronic equipment.
This 4-hr course is based entirely on Naval Education and Training Materials (NAVEDTRA 14176), Electricity and Electronic Training Series; Module-4 and covers Chapter-2 titled “Wiring Techniques”.
The course includes a multiple-choice quiz at the end, which is designed to enhance the understanding of course materials.
At the conclusion of this course, the student will be able to:
This course is aimed at students, professional electrical & electronics engineers, service technicians, energy auditors, operational & maintenance personnel, facility engineers and general audience.
Conductor splices and connections are an essential part of any electrical circuit. When conductors join each other or connect to a load, splices or terminals must be used. Therefore, it is important that they be properly made. Any electrical circuit is only as good as its weakest link. The basic requirement of any splice or connection is that it should be both mechanically and electrically as sound as the conductor or device with which it is used. Quality workmanship and materials must be used to ensure lasting electrical contact, physical strength, and insulation. The most common methods of making splices and connections in electrical cables is explained in this course.
Note that the electrical wiring practices vary greatly by locality and may vary depending on the differing state codes and interpretations, materials, tools and individual skills. This course is solely for educational purposes and it do not provide or imply certification for licensed electrical wiring activities.
In this course, you are required to study Naval Education and Training Materials (NAVEDTRA 14176), Electricity and Electronic Training Series; Module-4, Chapter 2 titled “Wiring Techniques”:
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In this course you have learned conductor splices and terminal connections, basic soldering skills, and lacing and tying wire bundles.
The first step in splicing or terminating electrical conductors is to remove the insulation. The preferred method for stripping wire is by use of a wire-stripping tool. The hot-blade stripper cannot be used on such insulation material as glass braid or asbestos.
A simple connection known as the Western Union splice is used to splice small, solid conductors together. After the splice is made, the ends of the wire are clamped down to prevent damage to the tape insulation. The staggered splice is used on multi-conductor cables to prevent the joint from being bulky. A splice that is used in a junction box and for connecting branch circuits; wiring is placed inside conduits. When conductors of different sizes are to be spliced, such as fixture wires to a branch circuit, the fixture joint is used. Knotted Tap Joint is used to splice a conductor to a continuous wire.
The terminals used in electrical wiring are either of the soldered or crimped type. The advantage of using a crimped type of connection is that it requires very little operator skill, whereas the soldered connection is almost completely dependent on the skill of the operator. Some form of insulation must be used with non-insulated splices and terminal lugs.
The wire to be soldered must be stripped to 1/32 inch longer than the depth of the solder cup of the terminal, splice, or connector to which it is to be soldered. This is to prevent burning the insulation. It also allows the wire to flex at the stress point. When you tin the wire, it should be done to one-half of the stripped length. When soldering a connection, take precaution to prevent movement of the parts while the solder is cooling. A "fractured solder" joint will result if this precaution is not taken.
The important difference in soldering iron sizes is not the temperature (they all produce 500º F to 600º F), but the thermal inertia. Thermal inertia is the ability of soldering tools to maintain a satisfactory soldering temperature while giving up heat to the joint to be soldered.
When using a soldering gun, do not press the switch for periods longer than 30 seconds. Doing so will cause the tip to overheat to the point of incandescence. You should never use a soldering gun on electronics components, such as resistors, capacitors, or transistors.
Ordinary soft solder is a fusible alloy of tin and lead used to join two or more metals at temperatures below their melting point. The metal solvent action that occurs when copper conductors are soldered together takes place because a small amount of the copper combines with the solder to form a new alloy. Therefore, the joint is one common metal.
The tin-lead alloy used for general-purpose soldering is composed of 60-percent tin and 40-percent lead (60/40 solder).
Flux is used in the soldering process to clean the metal by removing the oxide layer on the metal and to prevent further oxidation during the soldering process.
Always use non-corrosive, non-conducting rosin fluxes when soldering electrical and electronic components.
Solvents are used in the soldering process to remove contaminants from the surfaces to be soldered.
The purpose of lacing conductors is to present a neat appearance and to facilitate tracing the conductors when alterations or repairs are required. Flat tape is preferred for lacing instead of round cord. Cord has a tendency to cut into the wire insulation. When lacing wire bundles containing coaxial cables use the proper flat tape and do not tie the bundles too tightly. Never use round cord on coaxial cable. A double lace is required for wire bundles that are 1 inch or more in diameter.