Ballast Wiring - Electrical 101 Series ballasts can only be wired in series according to the diagram on the ballast. Parallel ballasts can only be wired in parallel according to the diagram on the ballast. Changing the wiring on a fluorescent light fixture from series to parallel, involves changing the ballast from a series to a compatible parallel ballast.Fluorescent Ballasts · Parallel Ballast Wiring · Fluorescent Lampholder Wiring Magnetek 6409 Wiring Diagram Gallery Assortment of magnetek 6409 wiring diagram. A wiring diagram is a simplified traditional pictorial depiction of an electrical circuit. It reveals the parts of the circuit as streamlined forms, and the power and signal connections in between the tools.