Terminals and device screws are rated for one or two wires, so techs splice several conductors together with a wire nut or crimp and run one short lead, the pigtail, to the terminal. In HVAC panels and thermostat wiring, pigtails keep common and power connections tidy and code-compliant. A loose or overheated pigtail is a classic intermittent no-heat or no-cool fault.
Three commons on one screw at the board, make a pigtail and land one wire, that's why it keeps dropping out.
Also heard as
- pig tail
Related terms
Contactor
A heavy-duty relay that uses a 24 volt control signal to switch line voltage to a compressor and condenser fan.
Whip
The short length of flexible conduit and wire running from the disconnect to an outdoor unit or air handler.
Cap
Short for capacitor, the part that gives compressor and fan motors the phase shift they need to start and run.
Same word, different worlds
Short length of wire spliced to several conductors so only one lead goes to a device terminal.
Boilers & BurnersA looped siphon pipe between a steam boiler and its pressure gauge or control, filled with condensate to block live steam.
Fiber OpticsA short fiber with a factory connector on one end and bare fiber on the other, spliced onto a cable to terminate it.