Five types of electrical wiring pinned to a wall

Test Your Knowledge: Types of Electrical Wiring

When you open a service panel or look behind a light switch, you may see a tangle of cables or a neatly organized arrangement of home electrical wiring. Depending on your knowledge, your perspective changes! When you know a few basic things about residential electrical wiring, you can more confidently find problems and diagnose solutions.

Residential Electrical Questions

Whether you’re an electrical student who is already attending residential electrical wiring classes or you’re thinking about enrolling because you have an interest in the trade, it’s always a good time to test your knowledge and learn something new! Explore the residential electrical questions below to find out how much you know about identifying and understanding the different types of electrical wiring.


Related: Residential Electrical FAQs
An electrician repairs home electrical wiring behind a light switch

What is residential electrical wiring vs. cable?

Electrical wire is a material that conducts electricity, and it is usually made of copper or aluminum. Most residential wires are wrapped in a nonconductive plastic coating. The plastic coating is sometimes called a jacket. A combination of two or more wires is called a cable. These are also wrapped inside a jacket to insulate the wires from touching other objects.

How do you read labels on electrical wiring?

The jacket, or insulation on an electrical wire is stamped with a code. This special code tells you what type of electrical wiring it is, as well as characteristics about its performance. THHN and THWN are the most common types of electrical wire used in residential construction. These letters stand for:

  • T: Thermoplastic, a heat-resistant plastic
  • H: Heat-resistant up to 167F
  • HH: Heat-resistant up to 194F
  • W: Moisture-resistant
  • N: Nylon-coated to resist damage from oil and gasoline

Nonmetallic cables also have codes and lettering on them, indicating the number and size of wires inside the jacket, or plastic coating. Common labels on nonmetallic cables include:

  • Nonmetallic Sheathed Cable (NM-B): Standard for dry indoor locations
  • Underground Feeder (UF): Suitable for outdoors and in-ground
  • Service Entrance (SE): Suitable for above-ground appliances and bringing power from a transformer to a house
  • Underground Service Entrance cable (USE): Suitable for outdoors and in-ground, similar to SE cables

Finally, the numbers on a nonmetallic cable tell you about the wiring size and number of wires inside the jacket. For example, a jacket with “12/2” contains two 12-gauge insulated wires.
Color coded residential electrical wiring

What is cable jacket color coding?

In addition to lettering and numbering, electrical wiring and jackets come in different colors to indicate how to use them. Color coding is a valuable tool in the electrical trade because it makes wires easily identifiable and promotes safer jobsites.


  • Black
  • Red

Sometimes Hot

  • Blue
  • Yellow


  • White
  • Gray


  • Green
  • Bare copper

Residential Electrical Wiring Classes

Now that you’ve learned more about residential electrical wiring, take your curiosity further. Check out our Electrical and Advanced Electrical program page, and find out if electrical classes are a good fit for your goals. Have questions? Contact Apex to learn more.



*Apex Technical School and its instructors are licensed by the State of New York, New York State Education Department.

Disclaimer: Apex Technical School provides training for entry-level jobs. Not everything you may read about the industry is covered in our training programs.

Components needed for rewiring a house wall socket

Residential Electrical FAQs

Electrical problems can be unsettling for most homeowners. Electricity powers many appliances in the home—and when it’s not working, it can be an inconvenience. Some electrical issues can also pose a potential fire hazard. These should be addressed right away by an electrician. In fact, all electrical problems, from a short circuit to rewiring a house, should be handled by a qualified individual with electrical skills and knowledge. Check out these common questions homeowners might ask about the electricity used to power items in their homes. 

What uses the most electricity in your home?

This basic electrical question is one of the first questions homeowners may ask. Residential energy consumption is the third-largest use of energy in the United States. These are the 10 most common sources of electricity consumption in 2019, as projected in the Annual Energy Outlook 2020: 

  1. Space cooling
  2. Space heating
  3. Water heating
  4. Refrigeration
  5. Lighting
  6. Clothes dryers
  7. Televisions
  8. Computers
  9. Furnace fans
  10. Freezers

Sometimes, homeowners don’t know when appliances are actively consuming electricity in their homes. In fact, some appliances use electricity even when they are switched off or not in use! These include printers, microwaves, routers and modems, and gaming consoles. 

Why does aoutlet spark when I plug in a device or appliance?

It’s normal to see the occasional small flash of electricity when you plug in a lamp, hair dryer or other appliance. However, if there is a spark every time you use the outlet—there might be a problem. The outlet could be short circuiting. Short circuits break down insulation and wires, and they are a potential fire hazard. An individual who works in the electrical trade can help diagnose the problem and recommend a solution. 

Why are plugs falling out of my wall outlet?

An electrician helps install a home electrical outlet

Over time and with frequent use, the outlet loosens and wears down. When this occurs, homeowners should have it fixed it right away. Like outlets that short circuit, loose outlets can spark too. These sparks are a potential fire hazard. If a socket is worn out, it is best to replace it right away to stay as safe as possible. Replacing an outlet requires rewiring part of the home’s electrical wiring. Make sure to call a qualified electrician who has the knowledge and hands-on skills to rewire a house wall socket easily and quickly. 



My circuit breaker trips all the time. Why?

This likely occurs when you use too many appliances at one time. And it may be an indication that your electrical circuits were not designed or installed correctly. Some powerful appliances, such as refrigerators and clothes dryers, require their own powerful circuits. An electrician can inspect the home’s circuitry to determine if too many appliances share a circuit, and ultimately make repairs to stop breaker trips.

An outlet with too many wires plugged into the socket

What is GFCI protection?

A GFCI outlet is designed to protect against electrical shock if it gets wet. GFCI outlets are required in bathrooms, garages, crawl spaces, basements, laundry rooms and other areas where water is present. They have a test button to turn off the GFCI, and a reset button to turn it back on after it has tripped. Having trouble getting a GFCI outlet to turn back on? Call an electrician who will be able to diagnose and fix the issue. 

Interested in learning if an electrical career path is right for you? Check out this blog post or contact us to learn more about the Electrical & Advanced Electrical program at Apex.


*Apex Technical School and its instructors are licensed by the State of New York, New York State Education Department.

Disclaimer: Apex Technical School provides training for entry-level jobs. Not everything you may read about the industry is covered in our training programs.

An electrical instructor shows a student how to take electrical measurements in shop class

A Day in the Life at Electrical School

Electrical programs help beginners in the electrical trade learn the basics for a fulfilling path in an exciting industry. From learning how to install a switch or an outlet, to finding a loose neutral in a wiring circuit, your days in an electrical school are spent obtaining skills that can help you grow your knowledge in the electrical field.

The average time in Apex’s electrical program involves splitting your time between both theory class – where you’ll learn about electrical theory, past methods and basic fundamentals – and shop class, where you’ll get hands on experience and tips of the trade to use in an entry- level position.

Meet the Instructors

Once students enroll at Apex, they meet their day to day instructors. These individuals have experience in the electrical trade and will introduce students to the concepts and practices of the trade. Instructors take the time to support students and give them space to practice wiring, splicing, grounding and the proper use of over current protection devices.

Tools of the Electrical Trade

Day-to-day learning in an electrical school involves knowledge of industry tools and equipment. Trades people use a variety of trade tools to complete the task at hand, including, but not limited to:

  • Digital multimeter
  • Tape measure
  • Conduit bender
  • Wire stripper
  • Wire crimper
  • Screwdrivers
  • Pliers

Basic tools are required to perform installation, repairs and routine maintenance. Instructors teach students the proper use and handling of electrical tools by giving them the opportunity to practice using tools in the shop with their peers. Students will also learn which tools they should keep on hand in their toolbelt at all times on jobsites.


Discover more about the electrical program when you visit the Apex campus. Contact us online for a tour.



*Apex Technical School and its instructors are licensed by the New York State Education Department. 

Disclaimer: Apex Technical School provides training for entry-level jobs. Not everything you may read about the industry is covered in our training programs.


plumbing versus electrical promo image

Trade Programs: Plumbing & Pipefitting vs. Electrical

Plumbing has delivered clean water and protected people from disease for centuries, starting with the Roman Empire. Today, plumbing allows people to enjoy the comforts of daily living, including hot water, showers, toilets, dishwashers and washing machines. Similarly, electricity helps power many plumbing appliances in homes, as well as refrigerators, computers, air conditioning systems and lighting. Without these technological advancements—and the skilled tradespeople who install, repair and maintain them—modern living would be very different.

At Apex Technical School, we offer training programs focused on helping students build technical knowledge and skills in plumbing and electrical. Interested in learning which program is a good fit for you? Discover the difference between these programs in the infographic below.

Plumbing and pipefitting versus electrical trade program infographic

*Apex Technical School and its instructors are licensed by the State of New York, New York State Education Department.


Disclaimer: Apex Technical School provides training for entry-level jobs. Not everything you may read about the industry is covered in our training programs.


What Are the 7 Trade School Programs at Apex?

There’s no one size fits all when it comes to school. Some students attend a traditional college to earn a two- or four-year degree. Many others discover a combination of knowledge, skills and technical training is the right path for them. A vocation education at trade school provides students with a variety of positive benefits. If you’re interested in attending trade classes, keep reading to learn about our programs.


Automotive Service Repair

At Apex, the automotive service repair program helps students learn to repair vehicles, help vehicles operate safely and get specialized training for an entry-level position. It provides a foundation of technical skills students use to evaluate mechanical systems and make repairs, as well as:


  • Fix and maintain the inner parts of the vehicle
  • Test major components when a vehicle breaks down
  • Work on engines, transmissions and brakes
  • Perform basic car care and maintenance, including oil changes


Students spend time in the classroom and shop where instructors incorporate diagnostic procedures, proper tool usage and much more. Auto mechanic classes are often a good fit for individuals who enjoy hands-on learning and have a passion for cars. Discover four signs auto mechanic school is right for you.


Air Conditioning, Refrigeration, Appliance/Controls

This vocational program focuses on teaching skills related to repairing and troubleshooting air conditioners, refrigeration systems, electrical control panels, major home appliances and gas-fired heating systems. Students in the HVAC program at Apex learn how to:


  • Use the basics of electricity for installation, service and maintenance
  • Repair and maintain domestic and commercial units
  • Learn about cooling towers, piping and ductwork
  • Follow codes and safety practices


HVAC training classes include both basic and advanced segments where students split their learning time between the classroom and shop. Interested in the HVAC field? Learn more about


Auto Body Repair

From preparing a car for body repairs to learning how to weld and retexture plastic, students in this vocational program train to enter the auto body repair industry. Students not only learn to improve a vehicle’s appearance but also:


  • Work on collision repairs, windshields and window glass
  • Fix structural, safety and cosmetic issues, such as dented doors and bumpers
  • Use paint and welding techniques
  • Restore older cars damaged by rust and age


In auto body repair classes, experienced instructors teach students techniques for fixing everything from minor to major auto collision damage. Explore the differences between the


Combination Welding Technology

Apex’s trade classes give students hands-on experience and teach a range of welding knowledge. Students learn techniques for welding repair and maintenance as well as how to use some forms of advanced welding equipment. Apex instructors focus on helping students:


  • Read blueprints and interpret welding symbols
  • Perform the four major welding processes, including SMAW, GMAW, GTAW and FCAW
  • Weld plates and pipes in multiple positions


Welding has been used for centuries to join two pieces of material together and continues to be a viable modern career option. Interested in learning if combination welding classes might be a good fit for you? Here are three signs you should consider welding training.


Electrical and Advanced Electrical

This trade school program prepares students to perform a variety of electrical tasks—from reading circuit diagrams and installing wiring for lighting to learning about green energy systems and more. Apex students learn with instructors and peers, study theories in the classroom and get hands-on experiences in the shop. Students training in the electrical program learn to:


  • Use basic tools and equipment to repair electrical conductors and components
  • Perform splices, bonding and grounding
  • Install circuit breakers, fuses and wiring
  • Install security systems, fire alarms, intercoms and other electronic systems


Electrical and advanced electrical classes span six segments and help students earn 900 hours of trade school training. Interested in exploring a bright future in the electrical field? Discover four reasons the electrical trade could be the path for you.


Construction and Building Skills

Individuals in the construction and building trade program touch upon a variety of skills—ranging from carpentry and electrical familiarity to plumbing, kitchen and bath knowledge. These tradesmen and women use their hands-on skills to:


  • Troubleshoot and repair electrical boxes and fittings
  • Frame windows and doors
  • Install light fixtures, wiring and countertops
  • Use power tools and plumbing blueprints


At Apex, students prepare to enter the construction field by taking six segments of carpentry and building skills classes, as well as learning to build a model house in the shop. Think you might be a good fit? Explore five signs a construction career path is right for you.


Plumbing and Pipefitting

Students in this vocational program learn how to install water heaters, water supply and waste disposal systems found in private kitchens and bathrooms. They also learn the basics and practice real techniques, including:


  • Assemble pipe sections, tubing and fittings
  • Locate leaks and repair pipes, fixtures and drainage systems
  • Follow blueprints, codes and safety specifications
  • Use a variety of hand and power tools, levels and other materials


Plumbing classes give students the opportunity to learn how to find the source of a problem, as well as what it takes to solve the problem. Wondering if you’re ready to pursue the plumbing trade? Here are four signs a plumbing career could be a good fit.


*Apex Technical School and its instructors are licensed by the State of New York, New York State Education Department.


Disclaimer: Apex Technical School provides training for entry-level jobs. Not everything you may read about the industry is covered in our training programs.

Student at Apex’s trade school for electricians is learning the electrical trade

What Is the Electrical Trade?

Electricity grew popular in the late 19th century, and this demand led to the formation of the electrical profession. In fact, many skilled electricians—such as Thomas Edison and Nikola Tesla—became famous for their electrical inventions.

The electrical trade consists of three areas: industrial, commercial and domestic. Throughout history, tradesmen have often specialized in one electrical discipline, but many have knowledge of more than one. Today, electricity powers nearly everything we use in our daily lives, and there are more exciting electrical trends on the horizon.

If you’re curious about trade schools for electricians or interested in basic training for electricians, you might be a good fit for the electrical trade. Learn more by exploring some common questions of the electrical trade.

    1. What does an individual in the electrical trade do?

      An electrical tradesperson installs, maintains and repairs power and lighting in homes and businesses. Some focus on construction or maintenance, while others specialize in both. Common tasks include:

      • Reading technical diagrams
      • Installing and connecting wires to circuit breakers, outlets, transformers or other systems
      • Using basic electrical tools of the trade
      • Repairing and replacing equipment when it breaks
      • Making quick repairs, often in small or dark areas
      • Correcting potential problems before they occur
      • Fixing motors, generators, and other machines
      • Taking proper safety precautions to avoid injury and electric shock

      All individuals in the electrical trade must follow local and state building codes and the National Electric Code.

    2. Where does an electrical tradesperson work?

      Many work in residential homes, installing wiring and solving electrical problems for homeowners who don’t have a tradesperson’s hands-on skills or knowledge in electrical theory, math and power distribution. However, many men and women in the electrical trade work in factories, warehouses or business buildings, applying their skills on a larger scale.

    3. How long is electrical trade school?

      Basic electrical training at a trade or vocational school involves students learning core electrical skills—both in the classroom and in the shop. Students spend many hours learning electrical safety, residential wiring, breakers and fuses, grounding, bonding, splicing, currents and outlets.

      Because learning a new skill is a time investment, students dedicate weeks and months to brightening their futures. At Apex Technical School, students in the electrical program gain 900 hours of entry-level electrician-skill training in as little as seven months.

      After studying several hundred hours in a classroom and shop setting, many students go on to apprenticeships and entry-level positions in the electrical industry.

      Learn more about the electrical trade at Apex, including classes and areas of study.

    4. What tools does an electrical tradesperson use?

      Learning how to use the right tools is an important part of basic electrical training programs. A tradesperson uses many tools to install, maintain and repair electrical boxes, fuses and wiring. Some valuable tools on your tool belt include:

      • Digital multimeter
      • Tape measure
      • Fish tape
      • Wire stripper
      • Wire crimper
      • Screwdrivers
      • Pliers

      As you learn about working in the electrical industry, read more about electrical tools of the trade and how to use them.

    5. How do I gain electrical skills in New York?

      Enrolling in an accredited trade school is a great place to start if you want to learn entry-level electrical skills. Because every vocational school for electricians has its own look, feel and personality, it’s a good idea to visit the school to see if you feel comfortable there. This is also an ideal time to ask questions you may have about technical school training, classes and instructors.

      At Apex Technical School in Long Island City, Queens, we meet one-on-one with you to discuss your goals and to explain what our school offers:

      • Seven 900-hour certificate courses
      • Hands-on technical training
      • Day and evening classes
      • Job placement assistance
      • Financial aid and work-study to those who qualify


Find out if Apex Technical School in New York is right for you. Contact us today to learn more about our trade school for electricians.


*Apex Technical School and its instructors are licensed by the State of New York, New York State Education Department.


Disclaimer: Apex Technical School provides training for entry-level jobs. Not everything you may read about the industry is covered in our training programs.

An Apex student uses electrical tools to install a light fixture

Electrical Tools of the Trade

Tradesmen in the electrical industry evaluate issues and diagnose problems using math, technical knowledge, blueprints and hands-on training. However, they require basic electrical tools to perform and complete installations and repairs. Discover how common tools for electrical work help many individuals diagnose and correct electrical problems in homes and businesses.

Common Electrical Equipment List

The right electrical tools are important to performing safe installation, maintenance and repair work. While technology and innovation have greatly improved electrical wiring tools over the years, there are some basic electrical tools tradesmen need, regardless of the work they do. These tools help individuals in the electrical industry work smarter, simpler and safer:

  • Digital multimeter
  • Tape measure
  • Fish tape
  • Wire stripper
  • Wire crimper
  • Screwdrivers
  • Pliers

Before you choose your tools, consider how each tool functions, its range of use and other components that make it a valuable item in your tool belt.

Digital Multimeter

A digital multimeter is an all-in-one tester for measuring voltages, currents and resistance in an electrical circuit. It helps tradesmen locate fluctuations in power due to bad wiring and prevent unintended electrical shocks. Individuals in the electrical industry consider this a standard diagnostic tool for taking electrical measurements.

Tape Measure

Many individuals in the electrical trade carry one or more tape measures. Tape measures help determine accurate heights for outlet and switch placement, assist with centering light fixtures and much more.

Fish Tape

Also known as draw wire or draw tape, fish tape routes new wiring through walls and electrical conduits. Tradesmen maneuver its narrow band of steel—along with a guide string—through tight spaces inside walls. Eventually, the guide string pulls wires and cables through the wall cavity.

Wire Stripper

Electrical tradesmen often need to strip or cut off insulation wires. Wire strippers are designed with various-sized teeth for cutting a variety of wire sizes. Some wire strippers feature ergonomically designed handles and curved blades that provide clean, precise cuts through tough wire and cable.

Wire Crimper

When an individual joins two pieces of metal wire, he or she generally uses a wire crimper to deform the pieces so they hold together. Wire crimpers allow electrical tradesmen to repair wires causing faulty circuit connections by providing a long-lasting seal.


Most individuals in the electrical industry need a variety of screwdrivers, including Phillips 1 and 2, straight blade screwdrivers, magnetic screwdrivers and screwdrivers with interchangeable tips.


A set of pliers is one of the most common tools of the electrical trade. Diagonal pliers specifically cut wires in tight spaces, while a set of do-it-all pliers with a squared-off tip are ideal for twisting, cutting and pulling wires.

Want to learn more about electrical? Explore the Electrical program at Apex.


*Apex Technical School and its instructors are licensed by the New York State Education Department.

Disclaimer: Apex Technical School provides training for entry-level jobs. Not everything you may read about the industry is covered in our training programs.


Electrical student using electrical technology on wall outlets

3 Top Trends in the Electrical Technology Industry

Increasingly, homeowners are turning to home alternative energy sources and smart technology to save money on electrical costs. They want electrical technology that is better for the environment and their pocket books. As electrical trends continue to evolve, it’s important to know which innovations are rising to the top of this exciting industry.

Residential Solar Electricity

Solar electricity isn’t a new invention. In fact, it’s been around since 1954 and has been used to power everything from space satellites to calculators and wristwatches.

Today’s homeowners, businesses, and governments are installing rows of solar cells on rooftops, hill sides, and farm fields. These solar cells—also called photovoltaic (PV) cells—convert sunlight into electricity. This feature makes solar power for homes highly desirable to individuals looking to save on electric costs over time.

As technology improves and demand for solar electricity goes up, systems such as solar hot water, solar heating and cooling, and solar electricity are becoming more cost effective for homeowners to install. According to the National Renewable Energy Laboratory, “Because of their flexibility, thin film solar cells can double as rooftop shingles and tiles, building facades, or the glazing for skylights.”

USB Wall Outlets

Grounded outlets have been a necessity in American homes since the 1960s. However, with modern devices like phones, tablets and computers, homeowners want faster, easier ways to charge their batteries.

Outlets designed specifically for USB ports can be installed by swapping out a traditional outlet. A new receptacle can mean homeowners don’t have to choose between the table lamp, charging their phone, and turning on the A/C window unit. Additionally, homeowners can rest easy knowing that as technology evolves, USB outlets are replaceable.

Lighting Upgrades

Many homeowners choose to incorporate more functional and modern lighting in their new homes and remodeling plans. Recessed and under-cabinet lighting offer a practical solution to dark kitchens or bathrooms while adding to the aesthetic of the room. Similarly, focused track lighting is a chance for homeowners to illuminate specific areas of the home, from portraits to art and more.

Tech-smart homeowners, however, choose upgrades that may require specific products and installation techniques. Home automation enthusiasts may want to install wireless lightbulbs, switches, dimmers, or outlets, which they can control by using Alexa, Amazon Echo’s virtual assistant.

Finally, homeowners with electrical panels and systems more than 20 years old generally opt to upgrade their amperage. With older systems, there is the potential for electrical fire. In order to safely provide enough power to a home, someone in the electrical field will inspect and make the proper conversions to ensure the system accommodates appliances in modern homes, including air conditioners, TVs, computers, stoves, refrigerators and lamps.


Disclaimer: Apex Technical School provides training for entry-level jobs. Not everything you may read about the industry is covered in our training programs.<

Nikola Tesla appears on a US stamp for his alternating current induction motor, which outperforms Edison’s direct current.

Tesla vs. Edison: Who Had the Better Electrical Career?

Thomas Edison and Nikola Tesla were contemporaries, and even rivals, as inventors in the late 19th and early 20th Centuries. In fact, Tesla was even an employee of Edison early in his career.

While there’s no doubt that Thomas Edison had a more financially prosperous career as an inventor, historians and engineers could argue that Tesla’s innovative electrical ideas make him the better inventor. Let’s review his accomplishments and career to find out how he impacted today’s electrical industry.

Alternating Current vs. Direct Current

Easily Tesla’s most important electrical contribution, the alternating current (AC) rivaled the direct current (DC) used in Edison’s power plants. Direct current was invented in 1800 by Alessandro Volta and evolved slowly over the years, becoming an everyday utility with Edison’s invention of the household lightbulb in 1882. Direct current refers to the flow of electricity in only one direction and is used by the following:

  • Batteries
  • Power supplies
  • Solar cells

While he was studying math and physics at the Technical University of Graz in 1882, Tesla came up with an alternating current idea. After moving to the United States, working at Edison’s headquarters, and his alternating current idea being rejected by Edison, Tesla pursued AC on his own. While AC had been invented in 1884, Tesla designed and invented an induction motor, which became today’s commonly used three-phase form. The difference between AC and DC is that DC is usually contained within a cell like a battery, and can be drained, while AC electricity flows in both directions and is used when you plug an appliance into an outlet.

With alternative currents the standard today, and considered more efficient than direct current, Tesla’s AC can be called the superior electrical invention. He had the foresight to pursue this complex form of electrical conduction, while Edison dismissed the invention, considering it unworthy of pursuit. As LiveScience explains, “Tesla’s inventions are the backbone of modern power.”

What Held Tesla Back?

LiveScience continues to explain that many of Tesla’s inventions did not outlive him, and he was unsuccessful financially. While extremely intelligent, notes his obvious mental illness, which resulted in debilitating obsessions. Additionally, financial backing was difficult to come by for Tesla’s large-scale innovations.


But despite mental and financial instability, Tesla’s legacy lives on, and his electrical genius cannot be discredited or overshadowed by the business success of Edison.


*Apex Technical School and its instructors are licensed by the New York State Education Department.
Disclaimer: Apex Technical School provides training for entry-level jobs. Not everything you may read about the industry is covered in our training programs.