Pigtail connections are very handy if there is more than one wire to be connected to a device such as an outlet receptacle or light fixture. Making electrical connections to a device in an electrical box is easy if there is only one cable in the box—you simply attach each circuit wire to a screw terminal on the device. It is more complicated, though, if the device needs to be connected to two or more circuit wires. Connecting them all under one screw terminal isn’t an option and should never be attempted. The proper installation method is to connect the wires using a short additional wire, known as a pigtail.
Pigtails are also useful if you need to extend the length of a circuit wire that is too short. If circuit wires are too short to easily connect to a device, adding a pigtail can lengthen the wires enough to make the wire connections.
How a Pigtail Works
A pigtail wire is a short length of wire that connects at one end to a screw terminal on an electrical device, with the other end joined to circuit wires that are connected together with a wire connector (wire nut). The most common application is when grounding a switch or receptacle, where green grounding pigtails are used to link the metal box and the device to the circuit grounding wires.
There are other applications for pigtails. For example, where a wall switch needs to control two or more light fixtures fed by different cables leading from the switch box, a short black pigtail wire is used to connect the screw terminal on the switch to the hot wires leading to the light fixtures. This links the switch to both outgoing hot wires in a code-approved manner.
It is important that the pigtail wires match the wire gauge of the circuit wires. This ensures that the pigtail can handle the amperage carried by the electrical circuit. The National Electric Code requires that a pigtail wire be at least 6 inches long. Electricians often cut their own pigtail wires from scrap wire they have on hand, but green grounding pigtails are also available with preattached grounding screws at one end for connection to metal electrical boxes.
When making a pigtail, choose a scrap of wire with insulation that is the same color as the circuit wires you are connecting: white pigtails when connecting to neutral wires, red or black when connecting to hot wires, green or bare copper when connecting to grounding wires.
Tools and Supplies You Will Need
Pigtailing is typically done within the context of other electrical repairs and replacements. Make sure you understand the overall requirements of the project when you are making pigtail connections.
Make Sure Power Is Shut Off
As with any electrical repair installation, always make sure that the circuit power has been turned off before connecting a pigtail. Use a circuit tester to verify that the power is off before proceeding.
Make the Pigtail Wire
Using a combination tool or wire cutters, cut a piece of scrap wire 6 to 8 inches long, the same color and wire gauge as the circuit wires. Strip about 3/4 inch of insulation from each end of the wire, using a combination tool or wire stripper.
Connect the Pigtail to the Device
Loop the bare wire at one end of the pigtail around the screw terminal on the device in a clockwise direction. Tight the screw terminal down to secure the wire loop. The loop of wire should fit tightly around the screw shaft, with no copper wire exposed.
Connect the Pigtail to the Circuit Wire
At the other end of the pigtail, connected the bare end to the circuit wires, using a wire nut or push-fit wire connector. Make sure no bare copper wire is exposed. Tug on the wires to make sure they are secure.
If connecting a green grounding pigtail to a metal electrical box, thread the green grounding screw attached to the pigtail into the threaded screw opening in the back of the electrical box. The free end of the grounding pigtail attaches to the other grounding wires with a wire connector. When metal boxes are used, there may be two grounding pigtails: one attached to the metal box, and one attached to the device, with the free ends of both pigtails joined to the circuit grounding wires using a wire connector. With plastic electrical boxes, there will be only a single grounding pigtail attached to the device.
Complete the Work
Once all wire connections are complete, tuck the wires back into the electrical box, secure the device to the box, and mount the cover plate. Turn on the power and test the operation of the device.