Article 200 — Grounded Conductors

Purpose

Article 200 of the National Electrical Code® (NEC®) defines the rules for identifying, connecting, and using grounded conductors — commonly known as neutral conductors.

These rules ensure that electrical systems remain safe, properly referenced to earth, and free from unwanted current flow on equipment grounding paths.

Key Concepts

1. Definition A grounded conductor is a system or circuit conductor that is intentionally connected to earth (ground) — typically the neutral in a single-phase or wye system.
2. Identification (200.6)
   • Grounded conductors must be distinctly identified throughout their length.
   • Common identification methods:
     • White or gray insulation
     • Three continuous white stripes on other color insulation
   • Re-identification is allowed only in conductors 4 AWG or larger and must be done at terminations.
3. Polarity (200.11)
   • Connections must maintain correct polarity — the grounded conductor must not be switched or fused in a way that breaks the return path before disconnecting the ungrounded (hot) conductor.
4. Use and Connection (200.2, 200.3, 200.4)
   • Grounded conductors must be connected only at authorized points, such as the service disconnect or separately derived system.
   • They must not be used for grounding or bonding equipment.
   • Each grounded conductor must have a dedicated path (no sharing between circuits unless specifically permitted).
5. Prohibitions
   • Never use the neutral (grounded conductor) as a grounding conductor.
   • Avoid parallel neutrals in multiwire branch circuits unless sized and installed per code.

⚙️ Key Takeaways

• The neutral conductor (white or gray) is vital for completing return current safely.
• Proper identification prevents reverse polarity and shock hazards.
• Neutral and equipment grounds must stay separate except at the service disconnect point.
• Misidentifying or misusing the grounded conductor can cause serious safety issues or code violations.

Equipment grounding conductor (EGC) is also known as “Grounding Conductor”, “Equipment (EGC)” is used to perform bonding between electrical equipment.

In the U.S. (NEC), the Equipment Grounding Conductor (EGC) is referred to as the Earth Continuity Conductor in BS 7671 and IEC-compliant countries. The function and purpose are the same; only the terminology differs.

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Special Conditions and Exceptions for GEC

• For rod, pipe, and plate electrodes, the maximum required GEC size is 6 AWG Copper or 4 AWG Aluminum. NEC 250.66(A)
• For Concrete-Encased Electrodes (Ufer Ground), the maximum required GEC size is 4 AWG Copper – 250.66(B)
• For grounding ring, the minimum required GEC size is 2 AWG Copper – 250.66(C)

GEC Sizing Table

The minimum grounding electrode conductor size based on 250.66 table is given below.

Here is the GEC sizing table in the image format for reference.

Examples of GEC Sizing and Calculations

Article 250.66 and Table 250.66 in NEC 2023 are used to properly size a Grounding Electrode Conductor (GEC) for AC system based on the largest ungrounded service-entrance conductor. Consider the following solved examples.

Example 1: The required size of main breaker in the main panel is 100-amp based on Table – 310.12(A) and 310.15(B)16 – NEC. What will be the suitable size of grounding electrode conductor (GEC)?

Solution:

Based on the determined size of 100-amp main breaker for a single story dwelling unit, the required size of service entrance or feeder to the subpanel is #4 AWG copper or #2 AWG aluminum (NEC – Table 310.12(A for Sizing Service/Feeders).

To determine the correct size of grounding electrode conductor (GEC) for 100-amp panel, refer to the NEC Table 250.66.

Therefore, the required ground wire size is #8 AWG copper or #6 AWG aluminum or copper-clade aluminum for #4 AWG copper or #2 AWG aluminum service feeding a 100-amp main panel.