Electrician's Licensing Practice Exam

What wire does NEC specify for referencing voltages in a circuit to Earth ground?

1. Black wire

2. Red wire

3. Green wire

4. White wire

The correct answer is: Green wire

The National Electrical Code (NEC) specifies that the green wire is used for grounding purposes, which connects electrical systems to Earth ground. Grounding wires are essential for safety, as they provide a path for fault current to flow safely to the ground, reducing the risk of electrical shock and fire hazards. In electrical installations, the green wire is specifically designated for grounding, and it is often used for bonding various parts of the electrical system to establish a common reference point to the Earth. This reference helps in stabilizing the voltage levels in the system and enhances protection against electrical surges or faults. Other wire colors, such as black, red, and white, serve different purposes. Black and red wires are typically used for hot wires that carry current, while the white wire is used for neutral, which provides a return path for current. However, they do not provide the same safety function as the green wire in relation to referencing voltages to earth ground.