When working with electrical wiring—whether you're installing a light fixture, replacing an outlet, or just curious—knowing which wire is hot is essential for safety and functionality.
In this article, we'll explain:
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What “hot” wire means
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Which wire colors are typically hot
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How U.S. electrical wire color codes work
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Common mistakes to avoid
🔥 What Is a Hot Wire?
A hot wire carries electrical current from the power source to the device (e.g., light, outlet, appliance). It's the live or energized wire and can cause shock if touched.
⚠️ Hot wires are dangerous. Always turn off power at the breaker box before working with any electrical wiring.
what color wires are hot
🟠 Common Hot Wire Colors in the U.S.
| Wire Color | Function | Hot? | Notes |
|---|---|---|---|
| Black | Hot | ✅ Yes | Most common hot wire color |
| Red | Hot (secondary) | ✅ Yes | Often used in 240V circuits or 3-way switches |
| Blue / Yellow | Hot (switched) | ✅ Yes | Used in switch legs or travelers |
| White (with tape) | Hot (re-identified) | ✅ Yes | Must be marked with black/red tape if used as hot |
| White | Neutral | ❌ No | Only hot if re-identified |
| Green / Bare | Ground | ❌ No | Never used as a hot wire |
🧰 Examples of Hot Wire Use
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Black wire in your light switch? → That’s likely the hot.
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Red wire in a 3-way switch circuit? → Also hot, but often a traveler.
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White wire with black tape in your outlet box? → It’s been repurposed as a hot wire.
💡 Pro Tip: Always Use a Voltage Tester
Wire colors are guidelines, but never assume. Especially in older homes or DIY installations, wires may not follow code.
✅ Use a non-contact voltage tester or multimeter to confirm which wire is hot before touching or disconnecting anything.
🏠 Typical Residential Circuit Example (120V)
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Black wire: Hot
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White wire: Neutral
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Bare or green wire: Ground
In this setup, the black wire delivers power, the white wire completes the circuit, and the bare/green wire ensures safety.
🔌 What About 240V Circuits?
For electric dryers, ovens, or HVAC systems:
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Black and Red wires: Both are hot (each carries 120V → combined 240V)
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White wire: Neutral
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Ground wire: Safety ground
🔧 A 240V circuit may have two hot wires—so both black and red are live!
🧯 Common Mistakes to Avoid
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Mistake #1: Assuming white is always neutral → Not true if re-identified!
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Mistake #2: Using green or bare wire as a hot wire → Never allowed by code.
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Mistake #3: Not labeling modified wires → Always use colored tape for re-identification.
🧠 Summary: Which Wires Are Hot?
| Hot Wire Colors | Black, Red, Blue, Yellow, or White with tape |
|---|---|
| Neutral Wire | White (unmarked) |
| Ground Wire | Green or bare copper |
📞 Need Help Choosing the Right Electrical Wire?
At TOT Wire & Cable, we supply color-coded THHN, NM-B, MC, and other residential and industrial cables—always up to code and ready for your project. Contact us for expert advice and bulk pricing.
