Originally Posted by: Washaare all humbuckers split into four wires

[font=trebuchet ms]That's the most useful configuration, in terms of offering the most switching options. A 4-wire humbucker brings both ends of both coils out for connection to your circuit. You can do Series/Parallel, coil-tap, or coil-splitting.

A 3-wire humbucker has a wire from one end of one coil ('in'), another one from the other end of the other coil ('out'), and a wire from the connection between the coils. This allows you to short out one of the coils, leaving a single-coil pickup. This is called a coil-tap connection.

The simplest configuration is a 2-wire setup, which just has the 'in' and 'out' wires of the coil connections.[/font]