The wiring for some PBG Pickups is sometimes causing confusion so I thought I would create a thread on this topic.
The problem is associated with the 4-wire Humbuckers sometimes being used instead of the 2-wire variety. The other issue is that there is not a "standard" for the colours of the wires from the manufacturers.
With the 4-wire pup shown below:
the Red wire is "hot",
the black is the "ground/Earth" which is soldered to the bare Shielding wire,
and the green and white wires (which are soldered together) link the two coils in the humbucker. These are normally taped to prevent them shorting on the other components.