Rat-tail splice

The bare splice can be insulated with electrical tape or by other means.

It can be made stronger by coating it with solder, which, however, renders the splice less mechanically flexible, or it can be twisted and then held in place by the internal metal spring or threads of a twist-on wire connector, also called a wire nut.

For safety reasons, neither covering the splice with tape only nor soldering the splice are permitted for 110 volts or higher by most, or all, North American building electrical codes.

The rat-tail 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.