A rat-tail splice, also known as a twist splice or a pig-tail splice, is an electrical splice done with both solid and stranded wire. It’s made with two or more bare wires and wrapping them together symmetrically around the common axis of both wires. The bare splice can be insulated with electrical tape or other means.

The splice is weak mechanically. It’s strengthened by coating it with solder, or it can be twisted and then held in place by the internal metal spring or threads of a twist-on wire connector. Because it is not very strong, the splice is not meant to connect wires that will be pulled or stressed. Rather, it is intended for wires that are protected inside an enclosure or junction box.^[1]