Technician exam question T0A03
Subelement T0, SAFETY· Group T0A
In the United States, what circuit does black wire insulation indicate in a three-wire 120 V AC cable?
- A.Neutral
- B.Hot (correct answer)
- C.Equipment ground
- D.Negative
WhyIn the United States, black wire insulation indicates the hot circuit in a three-wire 120 V AC cable. In standard US household wiring color coding, black insulation marks the hot (energized) conductor in a three-wire 120 V AC cable, answer B. White marks the neutral (A), green or bare copper marks the equipment ground (C), and "negative" (D) isn't a term used for AC wiring, that language applies to DC circuits instead.
Published 2026-08-28 · Last updated 2026-08-28 · Question text is verbatim from the 2026-2030 NCVEC Element 2 pool (public domain); the explanation above is original writing, see our methodology.
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