How do you identify ungrounded conductors?
Under the 2011 NEC, the requirements took up about 1/6th of a page. The 2014 NEC includes those verbatim (with changes to the numbering of the subsections), but also includes nearly half a page of additional requirements. The new requirements pertain to branch circuits supplied by DC systems operating at over 50V.
Let’s begin with the older set of requirements. These apply when the premises wiring system has branch circuits supplied from more than one nominal voltage system 210.5(C)(1). The idea is to distinguish the voltages; this applies, for example, where both 120V and 208V circuits are used.
Where differing branch voltages coexist, you must identify each ungrounded conductor of each branch circuit by system and phase (or line). This has to be done at all termination, connection, and splice points.
You can provide this identification by separate color coding or marking tape, among other means [210.5(C)(1)(a)]. Whatever identification means you use must be documented [210.5(C)(1)(b)].
This documentation must be readily available; for example, included in the legend section of the system drawings (assuming anyone working on the system can readily get access to those drawings). If it can’t be made readily available, you need to permanently post the identification information at each branch-circuit panelboard or similar distribution equipment.
