- - AGRICULTURE CORE CURRICULUM - - (CLF2000) Advanced Core Cluster: AGRICULTURAL MECHANICS (CLF2650) Unit Title: ELECTRICITY ___________________________________________________________________________ (CLF2654) Topic: Wire Splices Time Year(s) 2 hours 1 / 2 / 3 / 4 ___________________________________________________________________________ Topic Objectives: Upon completion of this lesson, the students will be able to: Learning Outcome #: (N-1) - Use approved safety measures in electrical wiring. (N-5) - Make four different splices. (N-7) - Exhibit safe habits when working around electricity. Special Material and Equipment: Electrician's pliers, knife, solid single 14 gauge wire, soldering iron, 50-50 resin-core solder, electrician's tape References: Cooper, E. L. (1987). AGRICULTURAL MECHANICS: FUNDAMENTALS AND APPLICATIONS. Albany, NY: Delmar Publishers. Erpelding, L. H. (1971). AGRIBUSINESS ELECTRICAL LESSON PLANS. Danville, IL: Interstate Printers & Publishers. Gustafson, R. J. (1980). FUNDAMENTALS OF ELECTRICITY FOR AGRICULTURE. Westport, CT: AVI Publishing Company. Phipps, Lloyd J., & Reynolds, Carl L. (1990). MECHANICS IN AGRICULTURE (4th ed.). Danville, IL: Interstate Publishers. Evaluation: Quiz by instructor. TOPIC PRESENTATION: Wire Splices A. Wire Splicing Fundamentals 1. Definition of a Good Wire Splice a. A wire splice is one wire connected to another wire. b. The splice should be made so that it will conduct electricity as well as the unspliced wire. c. The insulation applied over the splice should also be just as good as the insulation on the unspliced wire. 2. Splice Standards in the National Electrical Code a. Connectors and splices must be enclosed in a box. b. All splices or connections must be soldered or fastened with a solderless connector. c. Splices with soldered connections must be wrapped with electrician's tape equivalent in an amount to the original insulation. 3. Cutting and Stripping Wires a. If a knife is used to remove the insulation from the wire to be spliced, make sure the knife is sharp. b. The knife blade should cut through the insulation at a 30 degree angle, and then moved parallel to the wire. c. The blade should not be held at a 90-degree angle to the wire and run around the wire, for this may nick the wire. d. The cut should leave the end of the insulation tapered. 4. Soldering Splices a. Solder needs flux to help it stick to copper wires. 1) Resin is a good flux for electrical soldering. 2) Acid fluxes should not be used, because they are corrosive. b. Use a resin-core, 50-50 (50% lead, 50% tin) solder that has a lower melting temperature than solder used in plumbing. c. Place the soldering gun or soldering iron directly against the bare splice joint, keeping the wire on top of the iron. d. When the wire is finally hot enough, apply the solder from above to the wire allowing it to flow into every opening between the turns of wire to insure good electrical conduction. 5. Replacing the Insulation with Plastic Electrician's Tape a. Place the tape over the tapered end of the insulation and wind it spirally to the other end, allowing the turns to overlap a little. b. Keep the tape tight so it will come together and seal out moisture and dirt. c. Apply as many layers of tape as needed to build up the insulation to match what was taken off. B. Four Common Wire Splices 1. End Splice (Western Union Splice) a. The end splice is the most common type of small wire splice and is used to join to wires together so that the splice is as strong as the unspliced wire. b. The end splice can be completed in six easy steps: 1) Remove about three inches of insulation from the ends of the two wires. Remember to make a tapering cut on the insulation. 2) Clean the exposed wire by scraping or sandpapering. 3) Halfway down the length of its exposed section, bend each wire 90 degrees and hook the two together at the bends. 4) Holding the wires securely with a pair of pliers, twist them in opposite directions around each other. Make sure the ends of the wires are wrapped as tight as possible so their sharp points will not cut through the tape insulation applied later. 5) Solder the splice to insure proper conduction of electricity. 6) Properly insulate the splice with electrician's tape. 2. Tap or Branch Splice a. A tap splice is used when one wire must be tapped into another wire somewhere other than its end. b. The tap splice can be completed in six easy steps: 1) Remove at least two inches of insulation from the wire to which the tap is to be made. 2) Remove at least three inches of insulation from the end of the tap wire. 3) Clean the exposed wire by scraping or sandpapering. 4) Cross the wires holding them securely while the tap wire is wrapped tightly around the bare section of the other wire. 5) Solder the splice to insure proper conduction of electricity. 6) Properly insulate the splice with electrician's tape. 3. Rat-tail Splice a. The rat-tail splice is used on joints where there will be no strain on the wires, such as connecting wires in lighting fixtures, outlet boxes, and junction boxes. b. A rat-tail splice can be completed in six easy steps: 1) Remove about two inches of insulation from the ends of the two wires to be spliced. 2) Clean the exposed wires by scraping or sandpapering. 3) Cross the wires holding them securely with a pair of pliers and twist them together. 4) Fold the sharp wire ends back along the twist to prevent a sharp point from cutting through the insulation tape. 5) Solder the splice or use a twist on solderless connector (which provides its own insulation) to insure proper conduction of electricity. 6) Properly insulate the splice if it is soldered. 4. Two-Conductor Cord Splice a. This splice uses two staggered end splices to join twin conductors together. b. It can be completed in six easy steps: 1) Remove about six inches of insulation from each end of the two conductors. 2) Clean the exposed wire by scraping or sandpapering. 3) Make two staggered end splices, one for each conductor. a) The splices are staggered so that each splice is made alongside the insulation on the parallel conductor. b) If the splices are made side by side, there would be the danger of a short, and the splice would be bulky. c) Stagger the splices by cutting one wire of each set of conductors three inches shorter than its parallel wire. d) When making the splice, match the short end of one wire with the long end of the other conductor and join them. 4) Solder the splice to insure proper conduction of electricity. 5) Properly insulate the splice with electrician's tape. _________________________________________________________ ACTIVITY: 1. Practice doing each of the four different splices. _________________________________________________________ 6/26/91 OLR/tf #%&C