- Grounding Conductor Definition: A grounding conductor is defined as a wire intentionally connected to the earth, often referred to as a “ground conductor” or “case ground”.
- Safety Purpose: The primary function of the grounding conductor is to offer a safe path for fault currents, preventing electrical hazards by diverting current away from people and equipment.
- Grounded vs. Grounding: Understanding the difference between “grounding” and “grounded” conductors is crucial; the former relates to earth connection for safety, while the latter completes the electrical circuit.
- Color Identification: Grounding conductors can be recognized by their color—either green or green with yellow stripes, according to various international standards.
- Calculation Basics: When sizing a grounding conductor, it should be at least 25% of the phase conductor’s capacity, an essential basic electrical knowledge for safety in installations.
What is a Grounding Conductor?
A grounding conductor is defined as a wire or conductor intentionally connected to the earth. The grounding conductor is commonly known as a “ground conductor” or “case ground.”
Typically, the ground wire connects to the outer casing of electrical boxes, appliances, or tools. This is why the grounding conductor is also called a case ground.
The grounding conductor is used for safety purposes. In normal conditions, the grounding wire does not carry current.
During a fault condition, the grounding wire offers a path of low resistance, serving as an alternative route for the current.
As a result, the current flows through the grounding conductor, preventing it from passing through a human or the internal components of equipment.
The term “grounding conductor” is different from the “grounded conductor.” The term “grounded conductor” is correctly referred to as “grounded neutral conductor.”
However, it is often simply called a “grounded conductor” or “neutral conductor.”
The grounded conductor is used to complete the path of a circuit. Under normal conditions, the current will flow through the grounded conductor to complete the path.
What Color Wire is a Grounding Conductor?
The grounding conductor does not require insulation. It can be installed as a bare conductor. And if the insulated wire is used as a grounding conductor, the color of this conductor is green or green-yellow stripes.
Per standards like IEC-60446, AS/NZS 3000:2007 3.8.3, and BS-7671, grounding conductors are marked with green-yellow stripes.
In Brazil, India, and Canada, only green color is used for grounding conductors.
How to Calculate the Size of a Grounding Conductor
The grounding conductor is used to provide a low-impedance fault current path that reduces electrical equipment to near-zero electrical potential (voltage).
As a thumb rule, the size of a grounding conductor should not be less than 25% of the capacity of the phase conductor or over-current device.
According to NEC (National Electrical Code Academic and Science), a minimum size of a grounding conductor is decided as per the below table.
| NEC Table 250.122 | ||
| Rating or setting of automatic overcurrent device in the circuit ahead of equipment, conduit, etc. Not Exceeding (Ampere) | Size (AWG or kcmil) | |
| Copper | Aluminum or copper-clad aluminum | |
| 15 | 14 | 12 |
| 20 | 12 | 10 |
| 60 | 10 | 8 |
| 100 | 8 | 6 |
| 200 | 6 | 4 |
| 300 | 4 | 2 |
| 400 | 3 | 1 |
| 500 | 2 | 1/0 |
| 600 | 1 | 2/0 |
| 800 | 1/0 | 3/0 |
| 1000 | 2/0 | 4/0 |
| 1200 | 3/0 | 250 |
| 1600 | 4/0 | 350 |
| 2000 | 250 | 400 |
| 2500 | 350 | 600 |
| 3000 | 400 | 600 |
| 4000 | 500 | 750 |
| 5000 | 700 | 1200 |
| 6000 | 800 | 1200 |
