Twist on connectors connecting both ground and hot wire ends at a ceiling light (C) Daniel FriedmanElectrical Wire Splice Procedure
Step by Step details show how to join electrical wires or make splices

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Six steps to good electrical wiring splices & connections at electrical boxes or devices:

This article shows how to joint electrical wires using twist-on connectors at an electrical box.

This article series answers most 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 also discuss the use of electrical splices or wiring connectors outside of electrical boxes.

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Six Easy Tips for Successful Installation of A Twist On Connector Make a Good Electrical Wire Splice

Damaged wire (C) Carson Dunlop AssociatesIn making copper wire splices using a twist-on connector you should watch all of the six details we describe and illustrate below.

  1. Cut away damaged or nicked wire ends that might break off, causing a splice failure and a dead circuit or fixture that can be difficult to diagnose later. Sketch provided courtesy of Carson Dunlop Associates, a Toronto home inspection & education & report writing tool company.
  1. Strip back insulation 3/8" to 7/8" - depending on wire size and connector size

Watch out: If you don't strip enough insulation the insulation that is up under the twist-on connector cap may prevent a tight electrical connection between the wires even though the connector itself feels "tight" - you'll have a loose connection and flickering lights or overheating or even a fire.

Watch out: if you strip away too much wire insulation you'll see bare wire extending out below the bottom of the twist-on connector - inviting a shock or short circuit.


  1. Be sure the wire ends are straight and un-damaged and of equal length (photo below)

Electrical wires to be joined by a wire nut (C) Daniel Friedman

  1. If one of the wires is a multi-stranded wire such as for a light fixture, let that end extend about 1/8" past the solid wires.

    In my photo below I've extended the light-fixture's multi-strand ground wire about 1/8" past the end of the solid copper ground wire before installing the twist-on connector.

Electrical ground splice in the box (C) Daniel Friedman

  1. Hold the wires closely together. In my photo below I don't have the white neutral wires fully touching and close together but I'm working on it. Also I need to extend that white multi-strand lamp wire about 1/8" out past the solid copper wires before I start installing the twist on connector. If the wires are not straight I will use my pliers to make them as straight as I can before inserting them into the twist on connector.

Holding the neutral wires in position before splicing with a twist on connector (C) Daniel Friedman

  1. Twist on the twist-on connector (clockwise) until tight. Some electricians (and I) twist firmly until the wires themselves begin to twist together below the connector. My photo below shows all three sets of wires connected using orange twist-on connectors: white netural, black or hot wires connected using the twist-on connector, and the light fixture's ground wire connected to my circuit ground.

    At ELECTRICAL BOX GROUND WIRING we point out that if this had been a metal electrical box I'd also have had to bond the ground wire to the box itself.

Wire splices completed for a ceiling light fixture (C) Daniel Friedman

Some electricians, to make a particularly secure connection, perhaps where they feel there is extra risk, also wrap the assembly in electrical tape - a step not discussed in any of the manufacturer's instructions or catalogs we reviewed. I do this too, particularly when working with old house wiring installations.

See complete details on wire spicing given at ELECTRICAL SPLICES, HOW TO MAKE

References on twist on connector or Wire Nut® connector choices, wires, applications

On 2017-07-03 by vb - do I have to pre-twist wires before installing a wire-nut?

If you splice 2 number 12 wires in A J Box do they have to be twisted before you put a wire nut On


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