ARRL Technician Practice Exam

What is connected to the green wire in a three-wire electrical AC plug?

1. Hot wire

2. Neutral wire

3. Safety ground

4. Negative terminal

The correct answer is: Safety ground

In a three-wire electrical AC plug, the green wire is designated as the safety ground. Its primary purpose is to provide a path for electrical current to safely dissipate into the ground in case of a fault, such as a short circuit or insulation failure. This grounding ensures that potentially dangerous voltages do not build up, reducing the risk of electric shock or fire hazards. By creating a safe path for excess current, the grounding wire helps protect both devices and users. It's a vital component of electrical safety in household and commercial electrical systems, ensuring that if a device develops a fault, the electricity has a direct route to ground rather than potentially passing through a person. In contrast, the hot wire carries the current to the device, while the neutral wire serves as a return path for the current. The negative terminal choice commonly applies to DC circuits rather than AC, making it irrelevant in this context.