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KNOB & TUBE WIRING
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UNDERGROUND SERVICE LATERALS
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WIND ENERGY SYSTEMS
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ZINSCO SYLVANIA ELECTRICAL PANELS
How to make proper & safe electrical wiring splices & connections: this article answers basic questions about how splices (connections between two or more electrical wires) are made to connect & secure electrical wires together in residential or commercial building electrical wiring systems. We describe different types of connectors used to join two or more electrical wires, and we include installation details inclucing use of electrical tape. Sketch at page top courtesy of Carson Dunlop Associates.
Green links show where you are. © Copyright 2013 InspectAPedia.com, All Rights Reserved. Author Daniel Friedman.
Twist the electrical wires together tightly starting at or near the first bit of exposed wire. Always twist the wires in a clockwise direction. That way when you screw on a twist-on connector (which also is tightened by turning it clockwise) you won't be un-twisting your wires. We describe just how we twist wires together for a twisted splice just below in this article.
Trim off sharp points protruding from the end of the twist. Solder the twisted wires at the point where the twist began.
Secure the completed electrical wire splice with an approved twist-on connector as we discuss below.
Splicing three or more wires
The pigtail type of splice is best when joining three or more wires. The thing to guard against when more than two wires are involved in the twist is the tendency for one or more of the wires to remain fairly straight while the others are wrapped around it. When this happens the straight conductors can be pulled free of the splice fairly readily.
The way to prevent this is to make certain the twist is started with all the wires bent at approximately a right angle. (Don't bend current-conducting electrical wires at a sharp angle however.) Then if the bent wires are interlocked and held with pliers, the twist will continue as started.
For light wire, such as stereo speaker wires, when two wires are joined, cross about two inches of each end of prepared wire. Bend the ends of the wires over each other at right angles and twist them around each other.
For intermediate-sized electrical wires such as #14 copper wire (a 15-Amp electrical circuit) or #12 copper wire (a 20-Amp electrical circuit), you can usually strip about 3/4" of bare wire (special stripping tools are available that won't damage the wire or you can work carefully with wire cutters or a knife), and you can twist your wires together (clockwise) by holding the wires in one hand and twisting the bare ends using a single pair of pliers.
For heavy-gauge wire, two pairs of pliers are needed to make sure the connection is tight. Use one pair of pliers to hold the wires at the beginning of the twist.
Use the other pliers to twist the wires. Use wire cutters to trim off the excess wire so that no sharp ends can penetrate the tape. Solder the wires
The twist-splice in electrical circuit wires in a building must be capped or mechanically secured using an approved wiring connector.
Twist-on Electrical Connectors - "wire nuts" & MAAR Connectors
Other Types of Electrical Wire Splices & Wire Connectors: AlumiConn, AMP COPLAUM and other crimp connectors, Wago Wall Nuts,
Lugs which use a screw to bind wire into a holding device, and bus-bars which use a similar approach are used inside of electrical panels to join multiple neutral or ground wires together or to secure large-diameter wires.
Screw terminals are used on circuit breakers to secure electrical wires to these overcurrent protection devices.
Splices to Use When Extending Knob and Tube Electrical Wiring
Wires used in the electrical circuit of a home are not normally joined using soldering except where knob and tube wiring has been installed. These joints are taped as described above.
If your wires are not carrying any meaningful electrical current, such as stereo speaker wires, you can simply bend the wires parallel to one of the conductors and tape the bare splice from the end of the insulation on one side to the beginning of the insulation on the other side.
Spliced and soldered wire splices such as in stereo wires should always be taped. The right amount of tape to use on a joint is the amount that will provide insulation about as thick as the original insulation on the wire. A good brand of plastic electrical tape is best for wire joints.
How do we apply tape to a wire splice?
Apply the tape by wrapping it diagonally along the joint starting on the insulation at one end
Plastic tape sticks best if it is kept taut while wrapping. Continue the tape for an inch or so on the insulation at the other end.
Make as many wraps as necessary to build the tape to the proper thickness. Cut or tear the tape at the end of the last wrap and press it smooth around itself.
U.S. Building Electrical Wiring Color Codes & Conventions for 120V or 240V A/C Circuits
For our complete electrical wiring color code guides see ELECTRICAL WIRING COLOR CODES. Excerpts for the U.S. only are given just below.
Frequently Asked Questions (FAQs) about 120V and 240V electrical wiring splices & connections
Questions & answers or comments about electrical wiring splices, connections, connectors.
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Technical Reviewers & References
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