How to Identify Basic Electrical Wiring (Is White Or Black Wire Hot?)

Anytime you are doing any kind of electrical home repairs it is best to have a general understanding of what you are looking at! 

In this guide, you will learn:

  • What those wire colors mean!
  • How to identify if your outlet is in the middle of a circuit or at the end
  • Basic safety tips to keep you safe
  • And more!
how to identify basic electrical wiring

The most common question that homeowners have is whether the white or black wire is hot! The simple answer is that the black wire is the default 'hot wire' and the white is neutral.

As a licensed electrician, I ask, if you are uncomfortable or run into problems at any time while working on your project, please stop and call a local electrician to come finish the job.

Keep reading to learn about the black and white electrical wires, basic outlets, switches, and more!

Make Sure To Turn Off Power And Be Safe!

It is very important before beginning you turn off the power.  Electrical shocks can be very dangerous, and safety needs to be a priority! Use a non-voltage contact tester or voltage meter to verify the power is truly turned off.

Most jurisdictions require you to get an electrical permit to work on any electrical in your home, which will come with a small fee.  This ensures that it gets inspected to make sure it has been done safely and properly.

A good practice when doing electrical work is to wear rubber-soled shoes, a pair of clean leather gloves, and use hand tools with rubber grips.  Use a non-metallic ladder. Avoid standing in any wet spots while working.  Check with your local ordinances to find out what their electrical codes are.

Read Also >> How To Wire A 3-Way Light Switch?

Supplies You May Need For Wire Identification

  • Voltage Meter - Used to verify power is off
  • Non-contact Voltage Tester - Also used to verify power is truly off
  • Screwdriver - Used to remove outlet covers to see visible wiring

6 Steps To Identifying The Most Common Electrical Wiring

  1. Type of Outlet
  2. Types of Cables Used in General House Wiring
  3. Is The White Or Black Wire Hot? (Different Wire Colors)
  4. Identifying A Middle of the Run Outlet
  5. Identifying an End of the Run Outlet
  6. Identifying Switches

1 - Type of Outlet 

Identify what type of outlet are you working on:

  • Single Pole Switch - Controls lights from one location.
  • 3-Way Switch - Controls lights from 2 locations. 
  • 4-Way Switch - A switch that is in-between two 3-way switches allowing control of a light from 3 or more locations. 
  • 15 Amp Receptacle - Has a long slot (neutral), a shorter slot (hot), and a half-round grounding hole. 
  • 20 Amp Receptacle - Has a long slot with a horizontal slot coming off it (neutral), a shorter slot (hot), and a half-round grounding hole. 

It is important that the wire you are using is no smaller than the amperage rating of the outlet you are wiring.

Read Also >> How To Wire A 220-Volt Well Pressure Switch?

2 - Types of Cables Used in General House Wiring

For general wiring around the house NM cable is typically used; named for the non-metallic outer jacket. The size of the conductor cable should always match the size of the breaker at the panel.

  • NM #14/2 - 15 amp rating.  A white outer jacket enclosing 2 current carrying conductors and a ground
  • NM #14/3 - 15 amp rating.  A white outer jacket enclosing 3 current carrying conductors and a ground. This is used for wiring 3-way switches 
  • NM #12/2 - 20 amp rating.  A yellow outer jacket enclosing 2 current carrying conductors and a ground 
  • NM #12/3 - 20 amp rating.  A yellow outer jacket enclosing 3 current carrying conductors.  This would be used for wiring 3-way switches.
  • NM #10 -30 amp rating.  An orange outer jacket and is typically used for larger appliances such as an electric stove. 

3 - Is The White Or Black Wire Hot? (Different Wire Colors)

Lets look at what each individual wire color means:

The black wire is known as the hot wire; this is a current carrying conductor.  Its job is to carry power from the breaker to the outlet. 

The neutral wire color is white; this is also considered a current carrying conductor.  Its job is to carry any excess or stray voltage safely back to the electrical panel. Is the white wire hot? The answer is sometimes. If the white wire is wrapped in electrical tape, it is being used as hot wire instead. Home inspectors report mis-wired outlets that have reversed hot & white conductors as a defect.

The ground wire color is green or bare wire; this is not considered a current carrying conductor.  Its job is to protect, so it takes any short circuit current safely back to the ground rod outside of the house.  This helps to prevent you from getting a shock.  

Sometimes you will find a red wire; this typically is used for wiring 3-way switches and is called a traveler.  

4 - Identifying A Middle of the Run Outlet

When there is more than one cable coming into a box, this is an indicator power feeds more outlets down line.  The wires should be tied together with a pigtail so the outlet can be removed with out interrupting any other outlets down stream.

Read Also >> How To Wire A 220-Volt Outlet With 3 Wires?

5 - Identifying an End of the Run Outlet

An end of the run outlet will only have one wire coming into the box.  There will be no other power being sent to any other outlets.  

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Step 6 - Identifying Switches

A single pole switch has 3 wires connected to it; two black wires and a ground wire.  

A 3-way switch has 4 wires connected to it; two black, one red, and a ground.  It is important to note what wires hook to the lighter brass-colored screws; these are your travelers.  

A 4-way switch has 5 wires connected to it; two black, two red, and a ground.  It is important to keep the black and the red wires directly across from one another in pairs. These are the travelers from the 3-way switches. 

Frequently Asked Questions

How Do I Identify Electrical Wires?

Electrical cables are identified by the gauge of the wire and the number of current carrying conductors then separated by a hyphen.  For example, 14-2, the wire is a 14-gauge wire with 2 current carrying conductors and a ground.  

What Is Basic Electrical Wiring?

Typical household wiring is a cable with a non-metallic outer sheath.  Inside are at minimum 3 conductors, black and white wires, and a bare copper wire. The black is the hot, the white is the neutral, and the copper wire is the ground wire.

How Do I Identify A Neutral Wire?

The neutral wire is white in color.  It lands on the silver screw of a light fixture.  It will be wire nutted with other white wires in a switch box.  It will not have power on it. 

How Do You Identify Different Types of Wires?

On the outer sheath there will be markings on the entire length.  The type of insulation the outer sheath is made of will be a series of letters, for example THHN. The gauge and number of conductors will also be listed; for example, 14/2.

Read Also >> How To Convert Watts To Amps?

Final Thoughts On Identifying Basic Electrical Wiring 

By familiarizing yourself with basic electrical wiring, you will be able to easily work on your own wiring! Be sure to make safety your priority and follow good electrical safety practices! 

If you have any doubts about working on your electrical projects, please call a licensed electrician to come give you a hand! 

I hope you enjoyed this Home Inspector Secrets guide!

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