The article of this Circuit Conductors Identification and Phase Relations is to offer a method for identifying circuit conductors in an electrical system. This specification does not apply to wiring inside of manufactured panels or other manufactured equipment. Main keywords to be discussed here are Circuit Conductors Identification and Phase Relations. Power Cable Conductor Identification. Polyphase Circuits, ICEA Method Color Sequence, NEC Article 200, Grounding Conductor, Multi-Wire Lighting Branch Circuits.
Circuit Conductors Identification and Phase Relations in Plants
References
Insulated Cable Engineering Association (ICEA)
S-58-679 Control Cable Identification
International Electrotechnical Commission (IEC)
60227-1 PVC Cables of Rated Voltages Up to and including 450/750V
National Fire Protection Association (NFPA)
70 National Electrical Code (NEC)
Definitions
For the purpose of understanding this standard, the following definitions apply.
Grounded Conductor. A circuit conductor that is intentionally grounded.
Grounding Conductor. A conductor used to connect equipment Or the grounded circuit of a wiring system to a grounding electrode or electrodes.
The primary purposes for identification of circuit conductors and grounded conductor terminals are for safety of personnel during maintenance and for the ease of installation during new construction installations in process industry and plants.
Power Cable Conductor Identification
Grounded Conductor
An insulated grounded conductor of 18 mm2 (No. 6) or smaller shall be identified by a continuous white or natural gray outer finish or continuous white stripes embedded in the insulation along its entire length (NEC Article 200). An insulated grounded conductor larger than 18 mm2 (No. 6) shall be identified as above or by a distinctive white marking at its terminations (NEC Article 200). This distinctive marking may be white paint or white tape. White or natural gray color is not permitted for anything except a grounded conductor.
In branch circuit wiring, an important requirement concerns the use of two grounded Neutral conductors from different systems in the same enclosure, such as a conduit containing a 480/277-volt circuit and a 400/230 V or similar lower voltage circuit. In such instances, one system shall use the conventional white or natural gray color for the neutral, while the other system neutral shall be identified by the use of a white color with a colored stripe (not green) or other suitable and different means (such as labels) [NEC Article 210].
Grounding Conductor
A grounding conductor shall be identified by a continuous green color or a continuous green color with one or more yellow stripes unless it is bare [NEC Article 210]. No re-identification of a green-covered conductor is permitted. An insulated conductor larger than 18 mm2 (No. 6) shall, at the time of installation, be permitted to be permanently identified as a grounding conductor at each end and at every point where the conductor is accessible.
Identification shall be accomplished by one of the following means:
a. Stripping the insulation from the entire exposed length,
b. Coloring the exposed insulation green,
c. Marking the exposed insulation with green-colored tape or green-colored adhesive labels.
Ungrounded Conductor
An ungrounded conductor shall be identified by any color other than specified in above paragraph.
Multi-Wire Lighting Branch Circuits
The conductors of multi-wire lighting branch circuits and two-wire lighting branch circuits connected to the same system are recommended to conform to the following color code. The white or gray is mandatory.
The others are recommendations:
2-wire circuits: 1 black, 1 white (or gray)
3-wire circuits: 1 black, 1 white (or gray), 1 red
4-wire circuits: 1 black, 1 white (or gray), 1 red, 1 blue
The white or gray wire is considered to be the grounded conductor and shall be used for the “grounded neutral conductor” of the above circuits per NEC Article 210.
Polyphase Circuits
- Polyphase circuits shall be color coded to indicate voltage and phases as follows below.
- Conductor insulation shall be colored or provided with colored ribbon to indicate phases as follows:
- On three-phase, four-wire, delta circuits where the midpoint of one phase is grounded to supply lighting and similar loads, the phase conductor having the higher voltage to ground shall be identified by an outer finish that is orange in color or by tagging or other effective means. Such identification shall be placed at any point where a connection is made if the neutral conductor is also present.
Multi-conductor Control Cable Identification
ICEA Method Color Sequence
Multiconductor control cable conductors shall be identified (marked) per ICEA S-58-679, per Table 1 below for system without a grounded or grounding conductor.
Multiconductor control cable with a Neutral,or with a Grounding conductor, or with both a Neutral and Grounding conductor shall be identified (marked) per the modified ICEA S-58-679 color sequence per
Table above.
Multiconductor control cable manufactured outside the United States shall be identified (marked) per IEC 60227 paragraph 4.2 “Core Identification by Numbers”. The identification numbering system shall
begin with the number 1 and the numbers shall be printed in Arabic/english numbers. The numbers shall be in contrast to the color of the insulation of the conductor.
Phase Position Identification of 3 Phase, 3 Wire Service
- Phase rotation and identification in a three (3) Phase System shall be A, B, C, left to right, top to bottom, or front to back.
- Phase conductors which directly connect to the utility system or are in equipment subject to control and maintenance of the utility company shall be identified per the utility company’s requirements.