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Article 200

Use and Identification of Grounded Conductors

  1. Scope. This article provides requirements for the following:
    1. Identification of terminals
    2. Grounded conductors in premises wiring systems
    3. Identification of grounded conductors
    Informational Note: See Article 100 for definitions of Grounded Conductor, Equipment Grounding Conductor, and Grounding Electrode Conductor.
  2. General. Grounded conductors shall comply with 200.2(A) and (B).
    1. Insulation. 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 1000 volts or less, or impedance grounded neutral 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).
    2. Continuity. The continuity of a grounded conductor shall not depend on a connection to a metallic enclosure, raceway, or cable armor.
    Informational Note: See 300.13(B) for the continuity of groun‐ ded conductors used in multiwire branch circuits.
  3. Connection to Grounded System. 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 connec‐ ted so as to be capable of carrying current, as distinguished from connection through electromagnetic induction.Exception: Listed utility-interactive inverters identified for use in distributed resource generation systems such as photovoltaic and fuel cell power systems shall be permitted to be connected to premises wiring without a grounded conductor where the connected premises wiring or utility system includes a grounded conductor.
  4. Neutral Conductors. Neutral conductors shall be instal‐ led in accordance with 200.4(A) and (B).
  1. Installation. Neutral conductors shall not be used for more than one branch circuit, for more than one multiwire branch circuit, or for more than one set of ungrounded feeder conductors unless specifically permitted elsewhere in this Code.
  2. Multiple Circuits. Where more than one neutral conduc‐ tor associated with different circuits is in an enclosure, groun‐ ded circuit conductors of each circuit shall be identified or grouped to correspond with the ungrounded circuit conduc‐ tor(s) by wire markers, cable ties, or similar means in at least one location within the enclosure.

Exception No. 1: The requirement for grouping or identifying shall not apply if the branch-circuit or feeder conductors enter from a cable or a raceway unique to the circuit that makes the grouping obvious.

Exception No. 2: The requirement for grouping or identifying shall not apply where branch-circuit conductors pass through a box or conduit body without a loop as described in 314.16(B)(1) or without a splice or termination.

200.6 Means of Identifying Grounded Conductors.

  1. Sizes 6 AWG or Smaller. An insulated grounded conduc‐ tor of 6 AWG or smaller shall be identified by one of the follow‐ ing means:
    1. A continuous white outer finish.
    2. A continuous gray outer finish.
    3. Three continuous white or gray stripes along the conduc‐ tor’s entire length on other than green insulation.
    4. 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.
    5. 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.
    6. 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 all terminations.
    7. Fixture wire shall comply with the requirements for grounded conductor identification as specified in 402.8.
    8. For aerial cable, the identification shall be as above, or by means of a ridge located on the exterior of the cable so as to identify it.
  2. Sizes 4 AWG or Larger. An insulated grounded conductor 4 AWG or larger shall be identified by one of the following means:
    1. A continuous white outer finish.
    2. A continuous gray outer finish.
    3. Three continuous white or gray stripes along the conduc‐ tor’s entire length on other than green insulation.
    4. At the time of installation, by a distinctive white or gray marking at its terminations. This marking shall encircle the conductor or insulation.
  3. 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.
  4. 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 system. Identification that distinguishes each system grounded conductor shall be permitted by one of the following means:
    1. One system grounded conductor shall have an outer covering conforming to 200.6(A) or (B).
    2. The grounded conductor(s) of other systems shall have a different outer covering conforming to 200.6(A) or
      1. ARTICLE 200 — USE AND IDENTIFICATION OF GROUNDED CONDUCTORS
        200.6(B) or by an outer covering of white or gray with a readily distinguishable colored stripe other than green running along the insulation.
    3. Other and different means of identification allowed by 200.6(A) or (B) shall distinguish each system grounded conductor.
    The means of identification shall be documented in a manner that is readily available or shall be permanently posted where the conductors of different systems originate.
  5. Grounded Conductors of Multiconductor Cables. The insulated grounded conductors in a multiconductor cable shall be identified by a continuous white or gray outer finish or by three continuous white or gray stripes on other than green insulation along its entire length. Multiconductor flat cable 4 AWG or larger shall be permitted to employ an external ridge on the grounded conductor.

Exception No. 1: Where the conditions of maintenance and supervision ensure that only qualified persons service the installation, grounded conductors in multiconductor cables shall be permitted to be perma‐ nently identified at their terminations at the time of installation by a distinctive white marking or other equally effective means.

Exception No. 2: The grounded conductor of a multiconductor varnished-cloth-insulated cable shall be permitted to be identified at its terminations at the time of installation by a distinctive white marking or other equally effective means.

Informational Note: The color gray may have been used in the past as an ungrounded conductor. Care should be taken when working on existing systems.

  1. Use of Insulation of a White or Gray Color or with Three Continuous White or Gray Stripes.
  1. General. The following shall be used only for the groun‐ ded circuit conductor, unless otherwise permitted in 200.7(B) and (C):
    1. A conductor with continuous white or gray covering
    2. A conductor with three continuous white or gray stripes on other than green insulation
    3. A marking of white or gray color at the termination
  2. Circuits of Less Than 50 Volts. A conductor with white or gray color insulation or three continuous white stripes or having a marking of white or gray at the termination for circuits of less than 50 volts shall be required to be grounded only as required by 250.20(A).
  3. Circuits of 50 Volts or More. The use of insulation that is white or gray or that has three continuous white or gray stripes for other than a grounded conductor for circuits of 50 volts or more shall be permitted only as in (1) and (2).
  1. If part of a cable assembly that has the insulation perma‐ nently reidentified to indicate its use as an ungrounded conductor by marking tape, painting, or other effective means at its termination and at each location where the conductor is visible and accessible. Identification shall encircle the insulation and shall be a color other than white, gray, or green. If used for single-pole, 3-way or 4-way switch loops, the reidentified conductor with white or gray insulation or three continuous white or gray stripes shall be used only for the supply to the switch, but not as a return conductor from the switch to the outlet.
  2. A flexible cord having one conductor identified by a white or gray outer finish or three continuous white or

gray stripes, or by any other means permitted by 400.22, that is used for connecting an appliance or equipment permitted by 400.10. This shall apply to flexible cords connected to outlets whether or not the outlet is supplied by a circuit that has a grounded conductor.

Informational Note: The color gray may have been used in the past as an ungrounded conductor. Care should be taken when working on existing systems.

  1. Means of Identification of Terminals. The identifica‐ tion of terminals to which a grounded conductor is to be connected shall be substantially white in color. The identifica‐ tion of other terminals shall be of a readily distinguishable different color.Exception: Where the conditions of maintenance and supervision ensure that only qualified persons service the installations, terminals for grounded conductors shall be permitted to be permanently identified at the time of installation by a distinctive white marking or other equally effective means.
  2. Identification of Terminals.
    1. Device Terminals. All devices, excluding panelboards, 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.Exception: Terminal identification shall not be required for devices that have a normal current rating of over 30 amperes, other than polarized attachment plugs and polarized receptacles for attachment plugs as required in 200.10(B).
    2. Receptacles, Plugs, and Connectors. Receptacles, polar‐ ized attachment plugs, and cord connectors for plugs and polarized plugs shall have the terminal intended for connec‐ tion 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.
      2. If the terminal is not visible, the conductor entrance hole for the connection shall be colored white or marked with the word white or the letter W.
      Informational Note: See 250.126 for identification of wiring device equipment grounding conductor terminals.
    3. Screw Shells. For devices with screw shells, the terminal for the grounded conductor shall be the one connected to the screw shell.
    4. 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 a solid color that will not be confused with the white or gray finish used to identify the grounded conductor.Informational Note: The color gray may have been used in the past as an ungrounded conductor. Care should be taken when working on existing systems.
    5. Appliances. Appliances that have a single-pole switch or a single-pole overcurrent device in the line or any line-connected screw shell lampholders, 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 equip‐

    ment grounding conductor), shall have means to identify the terminal for the grounded circuit conductor (if any).
  3. Polarity of Connections. No grounded conductor shall be attached to any terminal or lead so as to reverse the designated polarity.

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