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How do I tell which wire is hot?

Electrical wiring can seem intimidating to homeowners without much experience working with it. Determining which wire is hot (live) versus neutral or ground is an essential safety skill when doing any electrical work. This guide will walk through several methods both experienced electricians and DIYers can use to reliably tell which wire is hot in various situations.

What Does “Hot” Mean?

In electrical terms, a “hot” wire is one that is energized and carries an electrical current from the power source. This is in contrast to a neutral wire which completes the circuit back to the panel or a ground wire which provides a safe path for stray electrical current. A hot wire has dangerous voltage running through it and contact can result in painful shock or electrocution.

Why Identifying the Hot Wire Matters

There are a few key reasons why correctly identifying which wire is hot matters:

  • Safety – Accidentally contacting a live wire can cause injury or death. Knowing which wire NOT to touch prevents electrical hazards.
  • Equipment connections – Most electrical equipment like lights, outlets, switches etc. must be wired properly by attaching the hot wire to the right terminal.
  • Troubleshooting – When diagnosing electrical problems, identifying the hot wire helps pinpoint issues like loose connections, damaged insulation, faulty components.
  • Electrical testing – Certain tests like checking voltage drop require probing the hot wire to get accurate measurements.

In short, properly determining the hot wire is vital both for personal safety and correctly working with electrical systems.

How to Tell if a Wire is Hot

There are several techniques both pros and amateurs use to reliably determine which wire is hot. Here are some of the most common methods:

Circuit Breaker Panel

The circuit breaker panel (or fuse box) that distributes power throughout the electrical system is the first place to start identifying hot wires. Here’s how:

  1. Locate the correct circuit you’ll be working on in the breaker box.
  2. Shut off the circuit breaker switch to cut power to that circuit.
  3. Go to the outlet, light fixture, or wiring you’ll be working on.
  4. The hot wire in the electrical box or cable will be the one that WAS connected to that circuit breaker before you shut it off.

This process isolates the hot wire by safely removing power from the circuit. The wire that was hot before shutting off the breaker is the hot conductor.

Voltage Tester

A non-contact voltage tester is handy, inexpensive tool every electrical DIYer should have. It detects if a wire is energized by sensing the electromagnetic field around it rather than directly contacting it. To use:

  1. Turn ON the power to the circuit you’re testing.
  2. Place the probe end of the tester near each wire in the electrical box one at a time.
  3. If the tester lights up, beeps, or displays a voltage value, that wire is HOT.

This method doesn’t require shutting off the power and quickly identifies the live wires in a circuit.


A digital multimeter (DMM) is another essential tool for any electrical work. Use it to directly measure voltage on individual wires:

  1. First shut OFF power to the circuit at the breaker panel for safety.
  2. Set the DMM to AC voltage mode – usually the V with a wavy line symbol.
  3. Touch the black probe to the neutral (white) wire or ground.
  4. Touch the red probe to one of the remaining wires.
  5. A 120-volt reading confirms the wire is hot.
  6. Repeat for the other wire(s). The one giving 120V is hot.

Multimeters provide definite hot wire verification but require safely disconnecting power first.

Clamp Meter

Clamp meters function similarly to multimeters but with one important advantage – they don’t require direct contact with wires. Current induces a magnetic field in any live conductor. The clamp’s jaws measure that field to detect current flow. To use:

  1. Clamp the jaw opening completely over one wire in the electrical box.
  2. Check the current reading on the display. Usually shown in amps (A).
  3. A non-zero current confirms that wire is hot.
  4. Repeat test on remaining wires. The conductor with current is the hot one.

Clamp meters are extremely handy for identifying live wires in cramped electrical boxes where probes can’t reach. They also don’t require powering down the circuit.

Terminal Screwdriver Test

A simple way to check for a hot wire in some situations is by quickly touching a screwdriver to the terminal screws:

  1. Make sure power is ON and the circuit is live.
  2. Touch the metal tip of an insulated screwdriver to the screw terminal of one wire.
  3. If you feel a tingle or the screwdriver is slightly drawn towards the terminal, that wire is HOT.
  4. Repeat for the other terminal(s). The one producing the effect is the hot conductor.

While not recommended on high-voltage circuits, this hands-on method can sometimes identify hot wires without tools.

Identifying Hot Wires by Color

In many electrical systems, the color of the wire insulation can indicate if a wire is hot, neutral or ground. Here is what the coloring typically signifies:

Wire Color Type
Black Hot / Live
White Neutral
Green / Bare Ground
Red Hot / Live (#2)
Blue Hot / Live (#3)
Orange Hot / Live (#4)
Yellow Hot / Live (#5)
Purple Hot / Live (#6)
Pink Hot / Live (#7)
Brown Hot / Live (#8)

So in most cases, a black wire can reliably be assumed to be hot. However, you should still verify with a tester or meter before touching. Some very old wiring doesn’t follow standard color codes.

When Wire Colors Don’t Help

While wire color is an indicator, you should never assume. There are some cases where it doesn’t reveal anything:

  • Old wiring – Very aged wiring often used whatever color insulation was available. Can’t rely on color alone.
  • Switched wires – In a switched circuit, the hot wire is sometimes spliced to a white neutral wire at the switch box.
  • Altered circuits – If wiring has been modified or extended, original color codes may not hold true.
  • Appliance cords – Cords on equipment like dryers often don’t follow standard hot, neutral, ground colors.

The only sure way to confirm a wire is hot is testing it with a meter, probe, or clamp. Never solely depend on color when dealing with electricity.

Important Safety Tips

When identifying hot wires, keep these critical safety guidelines in mind:

  • De-energize circuits at the breaker panel before wire testing when possible. Working on live wires is dangerous.
  • Wear electrical gloves and avoid jewelry when handling wires.
  • Only use insulated tools and always double-check for exposed metal or frayed wires.
  • Keep both hands behind your back or in your pockets when probing wires.
  • Never assume a circuit is off – always test wires for voltage first.
  • Stop work immediately if you feel a shock or tingle.
  • Have an experienced electrician handle any complex or high-voltage wiring.

Proper precautions are critical anytime you work near electrical hazards like identifying hot wires. Safety should always come first!


Identifying hot electrical wires is a crucial skill any time you work on electrical projects or repairs. While wire color provides clues, the only surefire way is testing with a meter, voltage probe, or clamp. Safety is paramount when checking for live wires. Following proper procedures and using insulated tools prevents electrical shock and accidents. Knowing which wire is hot and treating it with respect allows you to safely handle electrical systems.