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5 Means Of Identifying Grounded Conductors By NEC 200 Article
5 Means Of Identifying Grounded Conductors By NEC 200 Article (photo credit: inspectorsjournal.com)

Determining grounded conductors // NEC 200

Latest NEC requirements state at least five means of identifying grounded conductors. So, let’s go through each of them //

  1. Sizes 6 AWG or smaller
  2. Sizes 4 AWG or larger
  3. Flexible cords
  4. Grounded conductors of different systems
  5. Grounded conductors of multiconductor cables

1. Sizes 6 AWG or Smaller

An insulated grounded conductor of 6 AWG or smaller must 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 conductor’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 must be considered as meeting the provisions of this section.
  5. The grounded conductor of a mineral-insulated, metal-sheathed cable (Type MI) must 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 (article about permitted wiring methods), must be identified at the time of installation by distinctive white marking at all terminations.
  7. Fixture wire must comply with the requirements for grounded conductor identification as specified in 402.8 (see below)
  8. For aerial cable, the identification must be as above, or by means of a ridge located on the exterior of the cable so as to identify it.

Article 402.8 Grounded Conductor Identification – Fixture wires that are intended to be used as grounded conductors must be identified by one or more continuous white stripes on other than green insulation.

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2. Sizes 4 AWG or Larger

An insulated grounded conductor 4 AWG or larger must 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 conductor’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 must encircle the conductor or insulation.

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3. Flexible Cords

An insulated conductor that is intended for use as a grounded conductor, where contained within a flexible cord, must be identified by a white or gray outer finish or by methods permitted by 400.22.

400.22 – Grounded Conductor Identification //
One conductor of flexible cords that is intended to be used as a grounded circuit conductor must have a continuous marker that readily distinguishes it from the other conductor or conductors. The identification must consist of one of the methods indicated in 400.22(1) through (6) as shown below //

  1. Colored Braid
  2. Tracer in Braid
  3. Colored Insulation
  4. Colored Separator
  5. Tinned Conductors
  6. Surface Marking

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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 must be identified by system.

Identification that distinguishes each system grounded conductor must be permitted by one of the following means //

  1. One system grounded conductor must have an outer covering conforming to 200.6(A) or (B).
  2. The grounded conductor(s) of other systems must have a different outer covering conforming to 200.6(A) or 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 as allowed by 200.6(A) or (B) that will distinguish each system grounded conductor.

The means of identification must be documented in a manner that is readily available or must be permanently posted where the conductors of different systems originate.

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5. Grounded Conductors of Multiconductor Cables

The insulated grounded conductors in a multiconductor cable must 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 must 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 must be permitted to be permanently 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 must 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.

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Reference // NFPA 70: National Electrical Code (NEC), 2014 Edition (Purchase Now)

About Author //

author-pic

Edvard Csanyi

Edvard - Electrical engineer, programmer and founder of EEP. Highly specialized for design of LV high power busbar trunking (<6300A) in power substations, buildings and industry fascilities. Designing of LV/MV switchgears.Professional in AutoCAD programming and web-design.Present on

2 Comments


  1. Sam Taylor
    Feb 17, 2016

    A couple of things I see in the first photo, one aluminum conductor and one copper conductor under the same lug, and two copper conductors under the same lug, neither is probably listed for multiple wires.


  2. David Renshaw
    Feb 14, 2016

    Edvard,
    The title of the article is …”means of identifying grounded conductors”, and quite rightly it refers to the neutral (which in North American practice, would also include the mid-point conductor of a 240/120v. split-phase supply). But it completely omits to mention the presence of the circuit-protective wire – which is also a “grounded conductor”. The writer evidently assumes that everyone knows how this wire is colored or identified. And he also doesn’t deal with the case where the neutral & the protective functions are combined in a single wire. For the benefit of readers who might get the impression that in North America EVERY conductor with a deliberate connection to earth is white, he should say a bit more.

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