In the United States, what circuit does black wire insulation indicate in a three-wire 120 V cable?
Neutral
Incorrect. Neutral wires in a three-wire 120 V cable are typically white or gray, not black.
Hot
Correct. In the United States, black wire insulation indicates the ‘hot’ or ‘live’ wire in a three-wire 120 V cable.
Equipment ground
Incorrect. Equipment ground wires are usually green or bare copper, not black.
Black insulation is never used
Incorrect. Black insulation is commonly used in electrical wiring to indicate ‘hot’ wires, so this statement is incorrect.
Explanation
In the United States, electrical wiring follows a standardized color code to ensure safety and consistency. In a three-wire 120 V cable, the black wire typically indicates the ‘hot’ or ‘live’ wire. This wire is responsible for carrying the current from the power source to the electrical device. The importance of correctly identifying wire insulation colors cannot be overstated, as improper connections could lead to dangerous situations such as electrical fires or electrocution. Knowing that the black wire is ‘hot’ helps individuals safely perform installations and repairs while adhering to the National Electrical Code (NEC) standards.
T0A03 2022-2026