6.6 Grounded Conductor Identification, Switches & Panelboards

Identifying the Grounded Conductor — Article 200

200.6(A) Sizes 6 AWG or Smaller. An insulated grounded conductor of 6 AWG or smaller shall be identified by one of the following:

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 with their outer covering finished to show a white or gray colour but having coloured tracer threads distinguishing the source of manufacture;
5. Where the grounded conductor is part of a cable assembly and is not larger than 6 AWG, identification by means of a white or gray outer finish, or by a readily distinguishable marking at its terminations at the time of installation;
6. Fixture wire as specified in 402.8;
7. For aerial cable, the identification shall be as above or by means of a ridge located on the exterior of the cable.

200.6(B) Sizes 4 AWG or Larger. An insulated grounded conductor 4 AWG or larger shall be identified by a continuous white or gray outer finish, three continuous white or gray stripes, or at the time of installation by a distinctive white or gray marking at its terminations, encircling the conductor or insulation.

So above 4 AWG you may use black insulation with white tape at each end. Below that size the conductor itself must be white or gray.

200.6(D) 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: (1) one system grounded conductor with a continuous white outer finish and the other with a continuous gray outer finish; (2) a continuous white or gray outer finish with a different coloured stripe; (3) other identification allowed by 200.6(A) or (B) that distinguishes each system. The identification method must be documented in a manner that is readily available or permanently posted where the conductors are terminated.

200.7 Use of Insulation of a White or Gray Colour. The general rule is that white and gray are reserved for grounded conductors. 200.7(C)(1) permits a cable containing an insulated conductor with a white or gray outer finish to be used for single-pole, three-way, or four-way switch loops if the conductor with white or gray finish is used for the supply to the switch but not as a return conductor from the switch to the switched outlet, and the conductor is permanently reidentified to indicate its use as an ungrounded conductor by painting or other effective means at its terminations and at each location where the conductor is visible and accessible.

200.10 covers identification of terminals: the terminal for the grounded conductor shall be white in colour, and identification shall be by a metal or metal coating that is substantially white in colour or by the word white or the letter W.

200.11 Polarity of Connections. No grounded conductor shall be attached to any terminal or lead so as to reverse the designated polarity.

Article 408 — Switchboards, Switchgear, and Panelboards

Circuit Directories — 408.4

408.4(A) Circuit Directory or Circuit Identification. Every circuit and circuit modification shall be legibly identified as to its clear, evident, and specific purpose or use. The identification shall include an approved degree of detail that allows each circuit to be distinguished from all others. Spare positions that contain unused overcurrent devices or switches shall be described accordingly. The identification shall be included in a circuit directory that is located on the face or inside of the panel door in the case of a panelboard, and located at each switch or circuit breaker in a switchboard or switchgear. No circuit shall be described in a manner that depends on transient conditions of occupancy — "Bob's office" is not acceptable identification.

408.4(B) Source of Supply. All switchboards, switchgear, and panelboards supplied by a feeder in other than one- or two-family dwellings shall be permanently marked to indicate each device or equipment where the power supply originates.

Panelboard Overcurrent Protection — 408.36

In addition to the requirement of 408.30, a panelboard shall be protected by an overcurrent protective device having a rating not greater than that of the panelboard. This overcurrent protective device shall be located within or at any point on the supply side of the panelboard.

Exception No. 1: Individual protection shall not be required for a panelboard used as service equipment with multiple disconnecting means in accordance with 230.71. In panelboards protected by three or more main circuit breakers or sets of fuses, the circuit breakers or sets of fuses shall not supply a second bus structure within the same panelboard assembly.

Exception No. 2: Individual protection shall not be required for a panelboard protected on its supply side by two main circuit breakers or two sets of fuses having a combined rating not greater than that of the panelboard.

408.36(A) Snap Switches Rated at 30 Amperes or Less. Panelboards equipped with snap switches rated at 30 amperes or less shall have overcurrent protection not in excess of 200 amperes.

408.36(B) Supplied Through a Transformer. Where a panelboard is supplied through a transformer, the overcurrent protection required in 408.36 shall be located on the secondary side of the transformer. An exception permits a panelboard supplied by the secondary side of a transformer to be considered as protected by the overcurrent protection provided on the primary side of the transformer where that protection is in accordance with 240.21(C)(1).

408.36(D) Back-Fed Devices. Plug-in-type overcurrent protection devices or plug-in type main lug assemblies that are backfed and used to terminate field-installed ungrounded supply conductors shall be secured in place by an additional fastener that requires other than a pull to release the device from the mounting means on the panel.

Grounded Conductor Terminations — 408.41

Each grounded conductor shall terminate within the panelboard in an individual terminal that is not also used for another conductor.

An exception permits grounded conductors of circuits with parallel conductors to terminate in a single terminal if the terminal is identified for connection of more than one conductor. This is the rule that prohibits doubling up neutrals under one lug — an extremely common inspection finding, and dangerous because removing one circuit's neutral opens the other's.

Note the asymmetry: equipment grounding conductors may be doubled where the terminal is identified for it, but grounded (neutral) conductors may not, because a floating neutral is a shock and equipment hazard while a momentarily loosened EGC is not.

High-Leg Marking — 408.3(E) and (F)

408.3(E)(1) Phase Arrangement. The phase arrangement on three-phase buses shall be A, B, C from front to back, top to bottom, or left to right, as viewed from the front of the switchboard, switchgear, or panelboard. The B phase shall be that phase having the higher voltage to ground on three-phase, four-wire, delta-connected systems.

408.3(F)(1) High-Leg Identification. A switchboard, switchgear, or panelboard containing a 4-wire, delta-connected system where the midpoint of one phase winding is grounded shall be legibly and permanently field marked: "CAUTION — _____ PHASE HAS _____ VOLTS TO GROUND."

110.15 separately requires the high leg to be durably and permanently marked by an orange outer finish or by other effective means at each point of connection where the grounded conductor is also present.

408.3(F)(2) Ungrounded Systems. A switchboard, switchgear, or panelboard containing an ungrounded electrical system shall be legibly and permanently field marked: "CAUTION — UNGROUNDED SYSTEM OPERATING — _____ VOLTS BETWEEN CONDUCTORS."

Other Article 408 Rules

• 408.5 Clearance for Conductor Entering Bus Enclosures. Where conduits or other raceways enter a switchboard, switchgear, floor-standing panelboard, or similar enclosure at the bottom, the conduits shall not rise more than 3 inches (75 mm) above the bottom of the enclosure, and specified wire-bending space must be available.
• 408.7 Unused Openings. Unused openings for circuit breakers and switches shall be closed using identified closures or other approved means that provide protection substantially equivalent to the wall of the enclosure.
• 408.30 General. All panelboards shall have a rating not less than the minimum feeder capacity required for the load calculated in accordance with Part III, IV, or V of Article 220.
• 408.40 Grounding of Panelboards. Panelboard cabinets and frames, if of metal, shall be in physical contact with each other and shall be connected to an equipment grounding conductor. Where the panelboard is used with nonmetallic raceway or cable, or where separate equipment grounding conductors are provided, a terminal bar for the equipment grounding conductors shall be secured inside the cabinet, and the terminal bar shall be bonded to the cabinet. The equipment grounding conductor terminal bar shall not be connected to the grounded conductor of the system unless permitted elsewhere in the Code — that is, unless the panelboard is service equipment or supplies a separately derived system.
• 408.55 Wire-Bending Space Within an Enclosure Containing a Panelboard sets top, bottom, and side wire-bending space requirements per Table 312.6(B).