How to Identify a Hot Wire in a Light Fixture

How to Identify a Hot Wire in a Light Fixture

The hot wire carries electricity into the fixture, so use caution when handling

By Robert Ferguson

Three Exposed Wires
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Light fixtures have three wires to connect it to the junction box. The hot wire is the wire that carries electricity into the fixture. Common colors for hot wires are black, red or blue. The white wire is the neutral wire, which carries electricity away. If the neutral wire is interrupted for some reason, the ground wire, usually green, bare copper or silver, will prevent shock. Test the wires to verify which one is hot using a voltage meter. The meter will have two probes attached to it. Touching the ground wires with one probe while touching the other wires one at a time will identify the hot wire by activating the meter.

  • What You Need to Know
  • Safety is of the utmost concern when looking for a hot wire in a light fixture. You'll need a ladder or step stool, a set of screwdrivers, electrician's pliers, a voltage meter, electrician's tape and wire nuts before beginning such a project.

Step 1:

Turn on the light and find the circuit breaker panel box. Follow the label on the panel box to identify the correct breaker and turn it off. If there is no label, turn off the breakers one at a time until the light fixture goes off.

Step 2:

Place the ladder or step stool on a secure surface to gain access to the light fixture.

Step 3:

Loosen the light fixture cover plate from the junction box using a screwdriver to gain access to the wires. In some cases, it may be necessary to remove the entire light fixture.

Step 4:

Identify the black, red or blue wires in the junction box. Remove the wire nut holding the wires together. If more than one wire, separate them by untwisting the wires with electrician's pliers and spreading apart.

Step 5:

Identify the ground wires in the junction box. The wires are green, sliver or bare copper. Remove the wire nut holding the wires together. Make sure the all the ground wires are connected.

Step 6:

Identify the neutral white wires in the junction box. Remove the wire nut holding the wires together. Make sure all the neutral wires are connected.

Step 7:

Turn the circuit breaker back on. Make sure the light fixture switch remains in the "on" position.

Step 8:

Use a voltage meter to identify the wires. Purchase a voltage meter at electrical supply houses, a home improvement store or local hardware store.

Step 9:

Touch the ground "green, sliver or copper" wires or the neutral "white" wires in the junction box with one of the voltage meter probes. While maintaining contact with the grounds or neutrals, touch the common wires in the junction box one at a time with the remaining probe. The voltage meter will activate by making a clicking noise or lighting up when contacting the hot wire.

Step 10:

Repeat step 6 to verify that the identification of the hot wire is correct. Using caution is a priority when working around electric fixtures and their components because it can cause severe injury or death if not respected.

Step 11:

Mark the hot wire with electrician's tape or by screwing on a wire nut.

  • Tips & Warnings
  • Wear rubber soled shoes when working around electricity.
  • Do not touch bare wires with hands or fingers.
  • Test the voltage meter on a live wall outlet to verify that it is working properly.

About the Author

Robert Ferguson is a licensed building contractor with more than 30 years of experience, focusing primarily on residential remodeling, repair, renovation and construction.

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