Does positive wire go to Black or white?

In standard North American electrical systems, the positive (hot) wire connects to black, while the white wire is neutral. However, this applies primarily to alternating current (AC) circuits like household wiring. For direct current (DC) systems (e.g., batteries, automotive), red typically denotes positive and black negative. Always verify polarity with a multimeter before connecting wires, as color codes vary globally—white may serve as a phase conductor in some European systems.

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What’s the difference between AC and DC wire color standards?

AC systems use black for hot, white for neutral, and green/bare copper for ground. DC systems standardize red as positive and black as negative. Industrial three-phase power may employ brown/orange/grey phases. Pro Tip: Never assume wire colors—check documentation or use a voltage tester.

In residential 120V AC circuits, black delivers current to outlets, while white returns it to the panel. European systems use brown (L1), black (L2), and grey (L3) for phases with blue as neutral. Automotive DC systems prioritize red for battery positive and black for chassis ground. For example, connecting a car radio incorrectly—red to black—could short-circuit the head unit. Warning: Mixing AC/DC color conventions risks equipment damage or fire hazards.

Why do some systems use white as a hot wire?

White wires become hot when used in switch loops or 240V circuits. NEC permits reidentifying white with colored tape when repurposed. Older knob-and-tube wiring lacked standardization. Pro Tip: Wrap black tape around white wires functioning as hot conductors for safety.

In three-way switch setups, the white wire often carries switched hot current between devices—a notable exception to standard neutral use. Multiwire branch circuits may share a white neutral between two hot legs. For instance, kitchen split receptacles use black/red hots with a shared white neutral. Always verify with non-contact voltage testers, as legacy systems might have reversed colors.

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