Electrician's Licensing Practice Exam

Is it true that all voltages in a circuit reference to Earth ground via a black wire?

1. True, that is the standard

2. False, it uses a green wire

3. True, but only in specific cases

4. False, it depends on the circuit design

The correct answer is: False, it uses a green wire

The common practice within electrical wiring standards designates the green wire as the protective ground, which serves the purpose of grounding the electrical system to Earth. This grounding helps ensure safety by providing a path for fault currents, which can prevent electrical shock and equipment damage in the event of a fault condition. In terms of referencing voltages in a circuit, not all circuits reference to Earth ground through a specific wire color, as wiring conventions can vary based on the design and specific requirements of the circuit. Other wire colors—such as black or red—may be used as hot conductors, carrying current but not typically serving as a ground reference. Furthermore, certain applications and circuits use different grounding methods and wire configurations that may not adhere to a strict color code or standard for grounding. Therefore, while the protective ground is indeed designated as green in most cases, it is not accurate to state that all voltages reference to Earth ground via the black wire, making the answer option denoting this false.