Not sure, wether or not you switch the neutrals determines that...right? Or am I thinking of something else?
That's exactly what that means. :thumbsup:
Article 100 Definitions
Separately Derived System. A premises wiring system
whose power is derived from a source of electric energy or
equipment other than a service. Such systems have no direct
connection from circuit conductors of one system to
circuit conductors of another system, other than connections
through the earth, metal enclosures, metallic raceways,
or equipment grounding conductors.