Thhn Wire

  • According to UL Standard
  • PVC & Nylon
  • Rated Voltage:
  • Temperature:
    -40 ℃~60 ℃

THHN/THWN electrical wire is meant for use as general-purpose wiring for installation in conduit or other recognized raceway. THHN may also be used for machine tool, appliance and control circuit wiring.

thhn Wire data sheet

Conductor: Bare Copper

Insulation: PVC

Sheath Layer: Nylon

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Electrical Wires

THHN Wire Buyers Guide: Getting the best value for money

Why is it important to know what THHN wire is, and what it can do for a project? When electrical engineers design the wiring specification for plant, machinery or buildings, they must understand what types of wiring are best for the job. Knowing the capabilities of THHN vs THWN cables and wires, and understanding which one to buy may often determine success or failure of the project. Why is that?

That’s because each projects’ wiring specs differ. For instance, THHN wire size of one application may not be suitable for another application. Similarly, your specifications might work better with THHN aluminum wire, but it might not perform optimally if you substitute it with THHN copper wire. 

In this ZW Cable THHN Wire Buyers Guide, we’ll address some key factors about THHN electrical wire, and discuss various points to consider when making procurement decisions. Remember, THHN wire price isn’t the only consideration for which wire to use. We’ll tell you what else you should factor into these decisions.

  • What is thhn wire?

Electrical projects use various types of wiring. And within a project too, there might be different types of cables and wires necessary for various applications. THHN wire is a wire or cable produced per certain specifications. North American wire types must follow certain standards, including those defined by institutions such as Insulated Cable Engineers Association (ICEA), American Society for Testing and Materials (ASTM) and the National Electrical Manufacturers Association (NEMA).  One of those standards laid out is for thhn wire.

Thhn Wire

THHN is an acronym for “Thermoplastic High Heat-resistant Nylon-coated.” THHN electrical wire defines specific temperature ratings, insulation materials and condition of use. Typically, this type thhn wire is ideal for projects in dry, damp locations.

THHN electrical wire is very common in building electrical transmission. Electrical projects may opt for either THHN copper wire, or they may choose THHN aluminum wire. Because of its high transmission rating – up to 600 volts – THHN cable is the ideal choice for industrial as well as residential and commercial projects.

  • What is the difference between AWG and Thhn wire?

Both AWG and THHN refer to certain manufacturing standards for producing electrical wires and cables. Manufacturers must certify their cables per these standards so engineers and project managers can choose the right product for their application. Both are acronyms defining those standards, and both specifications come from industry groups or certification bodies.

AWG stands for American Wire Gauge, and it governs the thickness of the wire. THHN cable, on the other hand, stands for “Thermoplastic High Heat-resistant Nylon-coated. It is a designation of the characteristics of the cable, including the rated temperature of the application, the insulation material of the cable, and what conditions the wire operates safely to deliver optimal value to the project.

AWG wire gauge governs the thickness (cross-sectional dimension) of the conducting copper or aluminum conductor used in the manufacture of THHN wire. It (the AWG rating) governs the amperage (or number of amps) that a type THHN wire may safely transmit. Generally, the higher the AWG rating (number), the less amps it can carry.

THHN wire size may also be measured in AWG scale, but THHN primarily relates to the insulation of the cable. The purpose of insulation is to ensure current does not flow outside the confines of the insulation, but travels within the THHN aluminum wire or copper conductor.    

  • What’s the difference between thhn and thwn?

As noted earlier, different types of electrical cabling and wiring standards exist to guide engineers about which products are best for specific applications. When preparing to wire a building or appliance, it is important to understand which cable to buy and use for the application. That’s where an understanding of THHN Vs THWN is vital.

THHN is an acronym for “Thermoplastic High Heat-resistant Nylon-coated”, while THWN is an acronym for “Thermoplastic High and Water-resistant Nylon-coated.”


A variety of electrical installations extensively use both type THHN wire as well as THWN wire. THHN is a common choice when engineers want to connect branch circuits and for appliance wiring. THWN wire evolved from THHN wire, and like its counterpart is a nylon-coated but water-resistant wire. It (THWN) can function in similar operating environments as THHN, but without additional installation prerequisites to operate in wetter climates.

The major difference, therefore, between THHN Vs THWN, is the water-resistant feature of the latter over the former. Due to this additional characteristic (water-resistance), THWN has a clear advantage over type THHN wire:  Due to its PVC coating, it doesn’t require additional conduiting for safe installation. It may be laid out without a conduit, unlike THHN, which requires ducting.

As a result of this major difference between THHN Vs THWN, and because both types of cables have similar applications, many contractors simply carry THWN, instead of also hauling huge reels of THHN wire to job sites.  Usually, if the contractor provides appropriate conducting for the application, it’s possible to substitute type THHN wire instead of using THWN wire. That’s because the specification for THWN allows it to function better in wet conditions where, unless you run it through a conduit, THHN cable might not be appropriate.

  • What is thhn wire used for?

Like it’s THWN wire counterpart, THHN wire comprises of a flame-retardant conductor and a heat-resistant thermoplastic insulation. Manufacturers typically use extruded nylon – or similar materials – to produce the jacket.  Depending on THHN wire size, it may be used for numerous applications, including control circuits, the wiring of machine tools, or in the electrical systems of various residential, commercial or industrial appliances.

THHN cable is often a critical component in North American AC electrical distribution systems, and are a good fit for voltage between 110 to 600 volts. Depending on the type of application and THHN wire size, project engineers may either use wires with stranded or solid conductors. Electrical project managers may choose to use either THHN aluminum wire or THHN copper wire. 

Many wires may be dual-rated as THHN wire or THWN wire. These may work either for wet locations with temperatures up to 75°C (167°F), or in temperatures of up to 90°C (194°F) for dry applications.

  • What does thhn stand for?

THHN wire meaning stands for “Thermoplastic High Heat-resistant Nylon-coated.”. Type THHN wire is designated based on specific characteristics of the wire. These include temperature ratings, insulation materials used, and the permissible conditions for their use. Based on various criteria, including THHN wire size and the type of project, engineers may prefer THHN wire for both dry and wet conditions. Because of this dual usage (dry and wet)), most cable manufacturers label their THHN wire as THHN / THWN meaning they are good in either dry or wet conditions.

One characteristic of THHN cable is that its PVC insulation is comparatively (to other cables and wires0 is thinner, which influences the cables’ electrical properties. Under certain conditions, such as environmental exposure or contact with chemicals, current leakage may occur with THHN wire meaning it compromises the project. Toxic smoke might form when PVC burns, so THHN electrical wire might not be ideal in some applications.

The “N” in the THHN spec stands for “Nylon”. And because it uses a nylon coating, type THHN wire isn’t very flexible. Some contractors may prefer that feature, while others may not. However, THHN wire price is often more competitive than other equivalent alternate wires, such as XHHW building wire.

  • What features does a typical THWN and THHN cable have?

Depending on which type THHN wire you order, the cable may look slightly different. Typical choices include THHN aluminum wire or THHN copper wire. These come in either solid or stranded versions.


THHN wire size is determined according to the American Wire Gauge (AWG) size standards, which indicates the thickness of the conductor. Typically, THHN wire has three components to it. There is the inner core, which comes as either stranded or solid, depending on the THHN cable you choose.  There is an insulation that sheathes the core (conductor), and that insulation may be of PVC or similar material. Finally, most reputable THHN electrical wire manufacturers provide an outer jacket, often made from nylon.

The outer nylon jacket offers better handling capability to the THHN (or THWN wire) product. It (nylon) does not provide any great resistance to the overall cable against friction or moisture resistance. However, because PVC is moisture resistant, it protects the THHN copper wire or aluminum core from water or other forms of dampness.

Finding the right THHN Cable Manufacturer

If you go online, you’ll probably find many sites that offer “amazing” THHN wire price. Don’t let that fool you!  When looking for wiring for a critical project, it’s vital that you also remain focused on success of the project. Yes, price is an important consideration. But, when making THHN electrical wire procurement decisions, never underestimate the importance of quality. 

In this ZW Cable THHN Wire Buyers Guide, we’ve highlighted some of the critical qualities in wire manufacturing. Before placing your order, make sure the wire you purchase meets the highest manufacturing specs. If you order cables from a manufacturer without proper credentials or someone who has no expertise in THHN cable manufacturing, they may offer you a great THHN wire price, but poor quality could result in fire hazards to your project.

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