In the United States, what circuit does black wire insulation indicate in a three-wire 120 V cable?

• A. Ground
• B. Neutral
• C. Hot
• D. Return

Answer: (C)

Black wire insulation in a three-wire 120 V cable indicates a "hot" circuit. In electrical wiring, the hot wire carries the current from the power source to the load, such as an appliance or device. Identifying the hot wire is crucial for safe installations and maintenance, as it's the wire that can deliver electrical energy.

In standard wiring color codes, the black wire is typically used for one of the two hot conductors in a 120/240 V configuration. Recognizing black as the hot wire helps ensure proper connections are made and assists in understanding the overall electrical system, which is essential knowledge for anyone engaging in electrical work or amateur radio operations that involve wiring. The other wires in the configuration would typically include a white wire for neutral and a green or bare wire for ground, emphasizing the importance of correct identification to avoid potential hazards such as electrocution or short circuits.