Types of Electrical Wire: How to Choose the Right One for Your Home

If you’re still building your foundation in basic electricity, start with this beginner-friendly overview: 🔹 “Electricity 101: The Complete Beginner’s Guide to How Power Really Works”
After reading it, the concepts in this article will make a lot more sense.

Watch first: types of electrical wire – how to choose the right one

You walk into a home center or big-box store to run a new circuit for an A/C or replace an extension cord.
The clerk asks:

“What gauge do you need? Solid or stranded? NM-B or flexible cord?”

A lot of people guess, grab something that “looks right”, and hope for the best.

This video and article are here to change that. I’ll connect the most common types of electrical wire and cable to the devices you use every day, so you can finally see which types of electrical wire are actually safe for the job you’re trying to do.

Along the way, you’ll see how different wire types actually differ, and why picking the right electrical wire matters for both safety and comfort.

Types of electrical wire: what you’re actually choosing

When you’re wiring or upgrading a home in the U.S., picking the right wire type is one of the most important decisions you make.

Most wires look similar on the outside. But inside, they differ in:

• structure (solid vs stranded, single conductor vs multi-conductor cable)
• material (copper, aluminum, copper-clad aluminum)
• insulation and jacket (indoor, outdoor, high-temperature, etc.)
• voltage and temperature rating

Choosing wrong doesn’t just mean “it might trip the breaker”. It can lead to overheating, damaged insulation, and fire risk.

This guide will walk you through, in plain English:

• the main types of electrical wire and cable you’ll see in U.S. homes
• common conductor materials and where each makes sense
• how to match wire size, voltage rating, and environment to your project
• typical home wiring scenarios and what pros usually use
• key safety tips for installing and handling electrical wire

Basic types of electrical wire and cable you’ll see in U.S. homes

Let’s start with the big picture. When people say “electrical wire” in the U.S., they might mean:

• single conductors (THHN/THWN, solid or stranded)
• multi-conductor cables (NM-B like Romex, MC cable, flexible cords)
• signal cables (coax, Ethernet, etc.)
• and, increasingly, fiber optic cable for data

Below are the core categories you should recognize.

Solid wire (single solid conductor)

• What it is: One solid copper conductor with insulation around it. Very common in residential branch circuits when pulled in conduit.
• Pros:
  • holds its shape once bent
  • connections in screw terminals and wirenuts are very stable
  • ideal for permanent wiring hidden in walls, ceilings, and conduit
• Common uses:
  • THHN/THWN solid conductors in conduit for indoor circuits
  • individual conductors inside NM-B cable (e.g., 14/2, 12/2)

Stranded wire (flexible conductors)

• What it is: Many thin copper strands twisted together and covered with insulation.
• Pros:
  • much more flexible than solid wire
  • resists breakage under vibration, bending, or movement
• Common uses:
  • flexible cords on appliances and tools
  • stranded THHN/THWN conductors in conduit for longer runs or larger sizes
  • control wiring in panels and equipment

You’ll see both solid and stranded copper in residential work. For the same gauge, stranded takes slightly more space but is easier to pull and route.

Nonmetallic sheathed cable (NM-B, often called “Romex”)

• What it is: Multiple insulated conductors plus a bare ground, all wrapped in a nonmetallic outer jacket.
• Pros:
  • very common and cost-effective for indoor residential wiring
  • easy to route through studs and joists
  • widely documented in DIY guides and inspector expectations
• Common uses:
  • standard home branch circuits: lighting, general-purpose receptacles, small appliances
  • typical sizes: 14/2 (15-amp circuits), 12/2 (20-amp circuits), 12/3 (multi-wire or 3-way switch circuits)

Note: NM-B is not rated for wet locations or direct exposure to sunlight. For outdoor or damp locations, you need different cable types and methods.

Flexible cords and power cables

• What they are: Multi-conductor, stranded copper cords with a flexible outer jacket.
• Pros:
  • highly flexible, designed to be moved and handled
  • good for plugging and unplugging equipment frequently
• Common uses:
  • extension cords
  • power cords on appliances, computers, and tools
  • portable equipment and temporary power

The key thing: extension cords are not permanent wiring. We’ll come back to that in the FAQ.

Coaxial cable (coax)

• What it is: A central conductor, insulating layer, metallic shield, and outer jacket, arranged concentrically.
• Pros:
  • excellent for high-frequency signals
  • strong resistance to electromagnetic interference
• Common uses:
  • cable TV and satellite feeds
  • security cameras and some internet connections

Bare or insulated stranded conductors

• What they are: Multiple strands twisted together, sometimes bare, sometimes insulated.
• Common uses:
  • equipment grounds and bonding jumpers (often bare or green)
  • short connections inside panels and enclosures
  • automotive and low-voltage control wiring

Fiber optic cable (carrying light, not current)

Strictly speaking, fiber isn’t an “electrical” wire, because it carries light, not current. But in modern homes and buildings, it sits in the same pathways and raceways as power and data cables.

• What it is: Glass or plastic fibers inside protective jackets used to transmit light pulses.
• Pros:
  • extremely high bandwidth
  • long distances with low loss
  • immune to electromagnetic interference
• Common uses:
  • fiber-to-the-home internet connections (FTTH)
  • backbone links between network racks and data rooms
  • long-distance communication links

Common conductor materials: copper, aluminum, and CCA

Beyond structure, what the conductor is made of has a big impact on safety, performance, and price.

Copper wire

• Pros:
  • excellent conductivity
  • strong, ductile, and resistant to corrosion
  • forgiving at terminals when properly installed
• Common uses:
  • almost all standard residential branch circuits (outlets and lighting)
  • panelboard feeders in many homes
  • wiring inside appliances and equipment

For most homeowners and DIYers, copper is the default recommendation for branch circuits and small projects.

Aluminum wire

• Pros:
  • lighter and cheaper per amp carried than copper
  • common in larger sizes for long feeders
• Cons:
  • lower conductivity than copper (needs larger size for same ampacity)
  • more prone to oxidation at connections
  • requires special connectors and installation practices
• Common uses:
  • service entrance conductors and large feeders
  • some large appliances and subpanels, when installed to code

If you’re not familiar with aluminum, let a licensed electrician handle any aluminum feeder work. Aluminum can be safe, but only when all the details are done right.

Copper-clad aluminum (CCA)

• What it is: An aluminum core with a thin copper coating on the outside.
• Pros:
  • lighter and cheaper than full copper in some applications
• Concerns:
  • can be hard to identify visually
  • different mechanical and electrical behavior than solid copper
  • not generally recommended for standard household branch circuits

CCA can appear in some low-voltage or communication cables, but for 120/240 V house wiring, your safest bet is to stick with solid copper or properly installed aluminum feeders—not copper-clad aluminum branch-circuit cable marketed as a “cheap” alternative.

How to choose the right electrical wire

When you actually need to buy wire, it helps to slow down and think through the types of electrical wire you’re choosing between. In most home projects, you can think in four steps:

1. How much current (amps) will it carry?
2. Where will it be installed? (indoor, outdoor, wet, hot, etc.)
3. What voltage and system? (typical U.S. homes: 120/240 V)
4. What safety standards and approvals does it need?

Let’s break those down in plain language.

1. Current and wire size (ampacity)

If a wire is too small for the current, it overheats, insulation ages faster, and you increase fire risk.

In U.S. homes, a rough, common pattern is:

• 15-amp lighting and receptacle circuits
  → usually 14 AWG copper (in NM-B or conduit)
• 20-amp general-purpose receptacle circuits
  → usually 12 AWG copper
• High-power loads (electric water heaters, ranges, heat pumps, EV chargers, dryers, etc.)
  → often 10 AWG or larger, depending on amperage and length of run

Important: The correct size is determined by breaker rating, load, cable type, and installation conditions. Always check the National Electrical Code (NEC) ampacity tables and local amendments, or have a licensed electrician size the conductors for you.

If you’re running a new circuit, the safest approach is:

• follow the label on the appliance (minimum circuit ampacity, required breaker size), and
• match wire size to the breaker and code, not just “what somebody online said”.

2. Installation environment (indoor, outdoor, special conditions)

Where the wire lives matters as much as how big it is.

• Dry indoor walls and ceilings
  • commonly use NM-B cable (Romex-style) or copper THHN/THWN in conduit
  • protected from sunlight and moisture
• Outdoor or wet locations
  • require cable or conduit systems specifically rated for wet locations
  • e.g., UF-B cable for direct burial, THWN conductors in conduit, appropriate boxes, and waterproof fittings
• High temperature, oil, or chemical exposure
  • may require special insulation types (high-temp, oil-resistant, etc.)
  • don’t “force” standard indoor cable into places it was never designed for

If a label says “indoor dry locations only”, believe it.

3. Voltage rating

Every cable and conductor has a voltage rating. In a house with 120/240 V service, you want cable that is rated at or above that voltage.

• Typical U.S. residential circuits
  • NM-B and THHN/THWN conductors are commonly rated 600 V
  • this is more than enough for 120/240 V use
• Higher voltages (commercial/industrial)
  • use different cable types and system designs
  • should be handled by qualified professionals

Bottom line: never use cables with a voltage rating lower than the system they’re connected to.

4. Safety listings and code compliance

Wire isn’t just “wire”. It’s a safety product.

For U.S. installations, look for:

• UL Listed or ETL Listed marks on cable and devices
• proper labeling of:
  • gauge (AWG)
  • material (copper, aluminum)
  • cable type (NM-B, UF-B, THHN/THWN, etc.)
  • voltage and temperature rating

If a “too-cheap” cable on a marketplace site has unclear markings or no listing at all, treat that as a big red flag—especially for permanent household wiring.

Typical home wiring scenarios and what pros usually use

Let’s connect this back to real projects you might be thinking about.

Indoor home wiring (walls and ceilings)

• Typical choice:
  • 14/2 NM-B copper for 15-amp lighting or receptacle circuits
  • 12/2 NM-B copper for 20-amp receptacle circuits
• Why:
  • designed for indoor dry locations in wood-framed houses
  • easy to route and staple to studs
  • familiar to inspectors and electricians

Larger loads and equipment

• Typical choice:
  • 10/2, 8/2, or larger copper or aluminum cable for high-load circuits
  • exact size depends on breaker rating and distance
• Why:
  • heavy loads like electric ranges, heat pumps, tank water heaters, and EV chargers draw more current
  • voltage drop and conductor heating must both be considered

These circuits should be designed and installed to code, not just guessed.

Outdoor and outbuildings

• Typical choice:
  • UF-B cable rated for direct burial
  • or THWN conductors in PVC or metal conduit with outdoor-rated boxes
• Why:
  • UV light, moisture, and temperature swings are harsh on insulation
  • indoor-only cable outside will have a much shorter, less safe life

Communication and networking

• Typical choice:
  • Category 6 (Cat 6) twisted-pair cable for Ethernet
  • coaxial cable for TV and some internet feeds
  • fiber optic for high-speed backbone or ISP feeds
• Why:
  • data cares about bandwidth, interference, and distance
  • power wire is not a safe or effective substitute for proper data cabling

Safety tips when installing electrical wire

Choosing the right wire is only step one. How it’s installed decides whether it stays safe for decades.

Keep these principles in mind—whether you’re doing light DIY or supervising a contractor:

• Respect amp limits
  Don’t pack too many high-wattage devices onto the same circuit. Warm or hot faceplates and breakers are warning signs.
• Avoid kinks and excessive bending
  Forcing cable around very tight corners or pulling too hard can damage insulation or break conductors inside the jacket.
• Make solid, enclosed connections
  All splices should be inside approved junction boxes, with wirenuts or listed connectors, and no bare copper exposed.
• Secure and support the cable
  Use staples, straps, or cable clamps to keep wires from sagging, rubbing, or resting on sharp edges.

If you want an official, homeowner-friendly overview of common home wiring hazards and good habits, the Electrical Safety Foundation International has a helpful guide: Electrical Safety for Homeowners and Consumers.

And most importantly:

If you’re not sure what you’re doing, or a project touches the service panel, main feeders, or large loads, bring in a licensed electrician. It’s cheaper than a fire.

Frequently asked questions about electrical wire (U.S. homes)

Summary: learn wire types once, use that knowledge for years

Choosing the right electrical wire isn’t just about “will this melt?”. It shapes:

• how safely your home runs
• how long your devices and appliances last
• how often you deal with nuisance trips and weird electrical issues

If you understand:

• the main types of electrical wire and cable (solid vs stranded, NM-B vs flexible cords, coax, fiber)
• how those types of electrical wire interact with current, voltage, and environment,
• the difference between copper, aluminum, and CCA
• how current, voltage, and environment affect your choice
• and the installation details that keep wiring safe for decades,

you’ll be in a much better position the next time you’re planning a remodel, reviewing an electrician’s quote, or just thinking about adding that one more circuit in the garage.

Further reading

If you want to build a solid foundation in basic electricity before diving deeper into wiring, you might also like:

• “What Is Electric Current? The Basics You Actually Need”
  A friendly walkthrough of voltage, current, and resistance so you know what your wires are really carrying.
• “Voltage Explained: How It Pushes Current Through a Circuit”
  Understanding voltage makes it much clearer why some circuits run at 120 V and others at 240 V, and what that means for wire size.
• “Copper vs Aluminum Wire: Pros, Cons, and Real-World Applications” (coming soon)
  A more systematic comparison of conductor materials and where each makes sense in practice.

If this guide helped you feel more confident about electrical wire, consider subscribing to Engineer Tsai’s blog or YouTube channel. I’ll keep breaking down home electricity and practical wiring skills in clear, no-nonsense language—so you don’t have to guess the next time you’re standing in the wire aisle.