SPRK starts out with 4 life. After one frame, it loses one life and transfers to another conductive material within a certain range, and turns it into a 4-life SPRK. Then, it loses one life per frame, and disappears at 0. When two (or more) sparks have 4 life and have contradicting locations, it starts passing to multiple particles. This can be caused by PSCN/NSCN/METL conflict, or moving conductive stuff like WATR or BRMT, or parts of a conductor melting.