How to Identify Basic Electrical Wiring

Whether you’re changing an outlet, light fixture or switch, the first thing you need to know is what all those different colored wires are for.

September 29, 2021

Safety First

Before you start any electrical work, turn off the power from the home’s electrical panel to the outlet you will be working on. Place some tape over the switch in the breaker box so no one accidentally flips the breaker. Use a voltage tester or voltage meter to confirm power is disconnected.

Breaker Box

Changing a Light Fixture: Turn Off Power

Before beginning any electrical project, you should turn the power off at the breaker. It’s not enough to simply cut the power off at the light switch. Once the appropriate breaker is turned off, flip the light switch on and off to make sure there’s no power running to the light.

Photo by: Jalynn Baker

Jalynn Baker

What do the Different Color Wires Mean?

Here's a rundown of electrical wires:

The black wire is the "hot" wire, it carries the electricity from the breaker panel into the switch or light source.

The white wire is the "neutral" wire, it takes any unused electricity and current and sends it back to the breaker panel.

The green wire (or it can sometimes be uncolored) wire is the "ground" wire, it will take electricity back to the breaker panel, then outside to a rod that's buried in the ground. This is to prevent the electricity from running through you!

End-of-Run Outlet

When there's only one cable entering an outlet box, it means the outlet is the last fixture on the circuit. Power comes from the service panel along the black (hot) wire through other outlets, switches and light fixtures on the circuit and begins its return to the source through the white (neutral) wire. The black wire attaches to a brass terminal; the white wire, to a silver terminal.

CFI101wirea_s3x4

CFI101wirea_s3x4

Middle-of-Run Outlet

Two cables entering an outlet box indicate that the outlet is not the last fixture on a circuit. One of the black wires receives power from the service panel; the other sends it on to other loads on the circuit. The white wires allow current passing through the outlet and the other loads on the circuit to return to the panel.

CFI101wireb

CFI101wireb

Electrical Safety Rules

  • Wear rubber-soled shoes
  • Avoid wet floors
  • Use nonmetallic ladders
  • Use tools with rubber grips
  • Check with your local electrical-codes department to make sure you're doing any DIY project properly.

If you’re apprehensive about doing electrical work, have a licensed electrician do your updates or repairs. Licensed electricians will make sure that your home’s electrical system meets all required safety codes.

How to Replace a Standard Outlet With a GFCI Outlet

Ground fault circuit interrupter (GFCI) outlets block electrical power to prevent potentially dangerous shocks — they should be installed in any area that water is present such as bathrooms, kitchens and laundry rooms. Changing a standard outlet to a GFCI is a fairly easy and inexpensive project that will help protect you and your family.

Next Up

How to Change a Light Fixture

With 30 minutes and some basic tools, you can easily switch out a light fixture yourself. Follow these steps to tackle this simple yet high-impact project.

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