2017 National Electrical Code Article 200 Use and Identification of Grounded Conductors.
The grounded conductor, if insulated, shall have insulation that is..
(1) suitable, other than color, for any ungrounded conductor of the same circuit for systems of over 1000 volts, or (2) rated not less than 600 volts for solidly grounded neutral systems of over 1000 volts as described in 250.184(A)
Identification of terminals (A) device terminals.
All devices, excluding panel bards, provided with terminals for the attachment of conductors and intended for connection to more than one side of the circuit shall have terminals properly marked for identification, unless the electrical connection of the terminal intended to be connected to the grounded conductor is clearly evident.
Means of identifying grounded conductors, flexible cords.
An insulated conductor that is intended for use as a grounded conductor, where contained within a flexible cord, shall be identified by a white or gray outer finish or by methods permitted by 400.22.
Identification of terminals (c) Screw shells.
For devices with screw shells, the terminal for grounded conductor shall be the one connected to the screw shell.
Neutral Conductors (a) Installation
Neutral conductors shall not be used for more than one branch circuit, for more than one multiword branch circuit, or for more than one set of ungrounded feeder conductors unless specifically permitted elsewhere in this code.
Connection to grounded systems
Premises wiring shall not be electrically connected to a supply system unless the latter contains, for any grounded conductor of the interior system, a corresponding conductor that is grounded. For the purpose of this section, electrically connected shall mean connected so as to be capable of carrying current, as distinguished from connection through electromagnetic induction.
Identification of terminals (B) receptacles, plugs, and connectors.
Receptacles, polarized attachment plugs, and cord connectors for plugs and polarized plugs shall have the terminal intended for connection to the grounded conductor identified as follows. (1)identification shall be by a metal or metal coating that is substantially white in color or by the word white or the letter W located adjacent to the identified terminal.
Continuity of grounded conductors
Shall not depend on a connection to metallic enclosures, raceway, and cable armor.
Means of identifying grounded conductors 4 AWG or larger.
(1) continuous white OR gray outer finish (2)three continuous white or gray stripes along the conductors entire length on other than green insulation. (3) At the time of installation, by a distinctive white or gray marking at its terminations. This marking shall encircle the conductor or insulation.
Identification of terminals (D) Screw shell devices with leads.
For screw shell devices with attached leads, the conductor attached to the screw shell shall have a white or gray finish. the outer finish of the other conductor shall be of solid color that will not be confused with white or gray finish used to identify the grounded conductor.
Means of identifying grounded conductors at terminals
The identification of terminals to which a grounded conductor is to be connected shall be substantially white in color. the identification of other terminals shall be of a readily distinguishable different color.
Grounded conductors of different systems.
Where grounded conductors of different systems are installed in the same raceway, cable, box, auxiliary gutter, or other type of enclosure, each grounded conductor shall be identified by the system. Use separate identifiers conforming to 200.6 for each system.
Neutral conductors (b) Multiple circuits
Where more than one neutral conductor associated with different circuits is in an enclosure, grounded circuit conductors of each circuit shall be identified or grouped to correspond with the ungrounded circuit conductors by wire markers, cable ties, or similar means in at least one location within the enclosure.
Identification of Terminals (E) Appliances.
Appliances that have a single pole switch or a single pole over current device in the line or any line connected screw shell lamp holders, and that are to be connected by (1)a permanent wiring method or (2) field installed attachment plugs and cords with three or more wires (including the equipment grounding conductors), shall have means to identify the terminal of the grounded circuit conductor.
Polarity of connections.
No grounded conductor shall be attached to any terminal or lead so as to reverse designated polarity.
Means of Identifying Grounded Conductors (A) Sizes 6 AWG or smaller.
Shall be identified by one of the following (1) continuous white OR gray outer finish (2)three continuous white or gray stripes along the conductors entire length on other than green insulation. (3) Wires that have their outer covering finished to show a white or gray color but have colored tracer threads in the braid identifying the source of manufacture shall be considered as meeting the provisions of this section. (4) The grounded conductor of a mineral-insulated, metal-sheathed cable (type MI) shall be identified at the time of installation by distinctive marking at its terminations. (5) A single conductor, sunlight-resistant, outdoor-rated cable used as a grounded conductor in photovoltaic power systems, as permitted by 690.31, shall be identified at the time of installation by distinctive white marking at at terminations. (6)Fixture wire shall comply with the requirements for grounded conductor identification as specified in 402.8.