What is THHN?


THHN is the most popular style of copper building wire in the United States. THHN is an acronym which stands for “Thermoplastic High Heat-resistant Nylon-coated.”  

Specifically, THHN is a designation for a particular insulation material, temperature rating, and condition of use (suitable for both dry and wet locations) for electrical wire and cable.



THHN Wire Price, THHN Wire Specs, Buy THHN Wire








THHN Wire Prices


THHN Wire Prices are volatile. They’re volatile because they move up and down each day. Specifically, THHN Wire Prices move so frequently because they are tied to the metals market as THHN Wire is made from copper.


THHN Wire Prices usually only valid for 24 hours


Furthermore, THHN Wire Prices are usually only valid for 24 hours. As stated above, this is because metal prices change so frequently.  Specifically, Copper fluctuates with supply and demand, and the cost of production.


What moves Copper?


For instance, the price of copper could rise significantly during a housing boom, because builders demand record amounts of copper pipe and wiring to build millions of new homes. In a housing bust, the price of copper may drop. Copper and other metals are also tied to the strength of the stock market among many other factors. We have recently seen Copper over $4.00 per lb. The higher copper rises, the more THHN Wire will cost.


If you require THHN Wire Pricing now, contact your Unique Sales Agency salesperson or you can CONTACT US now for a quick price and availability. Thanks!



How is THHN Wire Used?


First, Copper Wire that is manufactured with THHN insulation is commonly used in Alternating Current systems. The USA and North America utilizes THHN building wire in “AC” systems between 150 volts and 600 volts.



THHN in Commercial & Residential Construction.


Typically, THHN building wire is used in commercial and residential construction. Electrical contractors use THHN every day in their projects from coast to coast. Specifically, it is commonly used because it is the cheapest of all the insulated copper building wires on the market.



THHN in Panel Building and Machine Tool Manufacturing.


Many times THHN will be dual rated as MTW. MTW stands for “Machine Tool Wire”. Furthermore, MTW conductors are usually used to connect control cabinets, or to wire up machine tool applications. Our manufacturer ABC Wire makes THHN that is all rated as MTW. It’s important to note that MTW wire complies with the National Electrical Code (NEC) and NFPA Standard 79.

It’s important to note, most THHN is also dual rated as THWN-2. Furthermore, when you order THHN from our manufacturer ABC wire your wire will be rated THHN-THWN-2-MTW.


THHN Wire Variations


First of all, THHN has a few variations that you may not think about too often including Solid or Stranded, Variation of Colors and Stripes, as well as well as a variety of reel sizes. Here’s what you need to know.



THHN Colors


Frequently, THHN is sold with a black jacket. However, more and more often, customers are ordering their wire in a variety of colors. This new trend is pushing the manufacturers to keep many different colors on hand to supply the demand.


  • Black.
  • White.
  • Red.
  • Blue.
  • Green.
  • Yellow.
  • Orange.
  • Brown.
  • Purple.
  • Gray.


Especially relevant, any of these color variations can also be combined with different colored stripes. Moreover, a common color that is often kept in stock is Green with a Yellow stripe.



Solid or Stranded THHN?


Important to note, Wire with THHN insulation comes in either solid or stranded, depending on the size you require. Typically, solid THHN is sold up to #10 AWG. AWG means American Wire Guage. AWG is a standardized wire gauge system used since 1857, mostly in North America for electrical wire. When #8 AWG or larger is required typically stranded THHN will be used for more flexibility.



Standard THHN-THWN-2 Reel Sizes  (Put Ups).


While ordering, keep in mind you can purchase your wire in many different standard sizes including:

  • 500 Foot Reels.
  • 1000 Foot Reels (Most Common).
  • 2500 Foot Reels.
  • 5000 Foot Reels.



THHN Sizes.


First, THHN wire starts at 14 AWG and can be manufactured through 1000 MCM. However, most customers usually only need up to 500 MCM or 600 MCM at the most. Specifically, MCM is an abbreviation for 1000 circular mils.1 MCM = 1 kcmil = 0.5067 square millimeters.


16 AWG and 18 AWG THHN?


When a customer calls asking for 16 AWG or 18 AWG THHN, they are actually looking for TFN (Solid), or TFFN (Stranded). Actually, yes, both of these are in the THHN family, but it’s important to note the difference.


Bigger than 1000 MCM THHN?


Usually, when sizes are required over 1000 MCM, we recommend XHHW-2 or XLP-USE building wire is used.

Specifically, Both XHHW and XLP have thicker insulation and jackets than THHN.  Below is a THHN Size chart from our manufacturer American Bare Conductor showing you all the THHN Sizes they stock, as well as the specifications.











American Bare Conductor THHN/MTW/THHN-2.

THHN - American Bare Conductor



  • 1– UL Standard 83 – Thermoplastic-Insulated Wires and Cables.
  • 2– UL Standard 1063 – Machine Tool Wires and Cables.
  • 3– UL Standard 66 – Fixture Wire.
  • 4– UL Standard 758 – AWM.



  • Specifically, Soft Annealed bare copper (per ASTM B-3) solid or standard (per UL 83).
  • Insulation of high-quality VW-1 or CT rated PVC (polyvinyl chloride) compound.
  • Dry rated 90°C, Wet rated 75°C for THWN.
  • Wet rated 90°C for THWN-2.
  • Outside jacket of clear, heat stabilized, abrasion resistant nylon.
  • Rating at 600 Volts.



  • Specifically, In accordance with National Electrical Code (NEC) 600-volt use in new construction, remodel or repair.
  • Used in applications where the maximum operating temperature does not exceed 75°C THWN, 90°C THWN-2 in wet locations and 90°C in dry locations.
  • First, THHN is Suitable for use in conduit and raceways installed underground, wet locations and/or where condensation and moisture may occur.
  • Second, THHN is Suitable for power and lighting in commercial, industrial and residential installations and appliance wire applications.
  • Third, THHN is Suitable for use in cable trays 1/0 and larger.
  • To be used in compliance with NEC article 310 – “Conductors for General Wiring” and article 210 – “Branch Circuits”.



THHN Wire Size Chart

Size(AWG or kcmil)Number of StrandsConductor Size(mm2)
Insulation Thickness(inches)
Outside Diameter
Approx. Net Weight(lbs./1000 ft.)
14 AWGSolid2.
12 AWGSolid3.
10 AWGSolid5.
14 AWG192.
12 AWG193.
10 AWG195.
8 AWG198.
6 AWG1913.
4 AWG1921.
3 AWG1926.
2 AWG1933.
1 AWG1942.
1/0 Ought1953.
2/0 Ought1967.
3/0 Ought1985.
4/0 Ought19107.050.007.62415.85195230260712
250 MCM37127.060.008.67817.23215255290851
300 MCM37152.060.008.73018.552402853201010
350 MCM37177.060.008.77719.742603103501170
400 MCM37203.060.008.82120.862803353801330
500 MCM37253.060.008.90222.913203804301650
600 MCM61304.070.0091.05126.703554204751985


About ABC Wire

Located in LaSalle, IL, American Bare Conductor, Inc. (ABC) offers comprehensive lines of bare copper and insulated wire and cable products for industrial applications as well as for special uses.

Furthermore, as one of the premiere wire and cable companies in the United States, ABC specializes in the improvement of production techniques and continuing development of our personnel. Most of all, we do this to meet the most demanding environments imaginable.

Important to note, For over 25 years, ABC leverages technology with traditional values, quality, reliability and customer service to assure long-term relationships with all clients. Moreover, It has made ABC one of the leaders in bare copper wire manufacturing.

Beginning in 2006, under new management, ABC has invested significantly in a new facility and state-of-the-art machinery. Specifically, this machinery lets us implement our expansion project which encompasses building wire manufacturing.

Additionally, ABCi Building Wire, a marketing trade division of American Bare Conductor, currently offers building wire for commercial and residential applications. Furthermore, These products meet all applicable Underwriters Laboratories, UL / cULus standards.

Finally, American Bare Conductor and its divisions strive to exceed the most stringent specifications and are committed to client satisfaction and service excellence.

For a quote on your THHN Wire from ABC please contact your Unique Sales Agency salesperson or you can CONTACT US now for price and availability. 



MM2 to AWG Conversion

Specifically, this is a list of European wire sizes coverted to United States Wire sizes. Additionally, if you require a size not listed just give us a call or send an email.

30 AWG = 0.05 MM2.

28 AWG = 0.08 MM2.

26 AWG =  0.14 MM2.

24 AWG = 0.25 MM2.

22 AWG = 0.34 MM2.

21AWG = 0.38 MM2.

22 AWG= 0.50 UL MM2.

20 AWG = 0.50 MM2.

19 AWG =  0.75 UL MM2.

18 AWG = 0.75 MM2.

18 AWG UL =  1.0 UL MM2.

17 AWG = 1.0 MM2.

16 AWG = 1.5 MM2.

14 AWG = 2.5 MM2.

12 AWG = 4 MM2.

10 AWG = 6 MM2.

8 AWG = 10 MM2.

6 AWG = 16 MM2.

4 AWG = 25 MM2.

2 AWG = 35 MM2.

#1 AWG & 1/0 =  50 MM2.

2/0 = 70 MM2.

3/0 = 95 MM2.

4/0 = 120 MM2.

300 MCM = 150 MM2.

350 MCM = 185 MM2.

500 MCM = 240 MM2.

600 MCM = 300 MM2.

750 MCM = 400 MM2.

1000 MCM = 500 MM2.






A Double shield is two shields, one over the other. Specifically, Maximum coverage of a double shield is 98%.



Duct, is an underground or overhead tube for carrying electrical conductors. Additionally, You may hear the term “In Duct”. Similar to Conduit.



Duplex is two conductors twisted together, usually with no outer covering. Because this word has a double meaning it is possible to have parallel wires and jacketed parallel wires and still refer to them as a duplex.



To apply rated voltage to a circuit or device, such as the coil of a relay, in order to activate it.



Abbreviation for ethylene propylene rubber. Also Important to note, EPR polymer is chemically cross-linked.



First of all, The ETL Testing Laboratory was originally founded by Thomas Edison and the ETL trademark is now owned by Intertek. Because of its importance, you can read more information about ETL and other nationally recognized testing laboratories in the article “It has to be UL or does it?”.



The process of continuously forcing both a plastic or elastomer and a conductor core through a die, thereby applying a continuous coating of insulation or jacket to the core or conductor. Additionally, You can see Extrusion in this video from “How it’s made”.






Filled strand is just as it sounds, with the strands being filled with a substance. Additionally, Conductors in which the interstices between the individual wires are filled with a compound to prevent moisture migration along the conductor.



a) First, fillers are used in a multi-conductor cable to occupy the voids formed by the assembled conductors. This is done so that the resulting configuration will be round. b) Second, An inert substance added to a compound to improve properties or decrease cost.



Flame Resistance is the ability of a material not to propagate flame once the heat source is removed. Essentially, it is the wire’s ability to stop from burning.


Flame Retardance is the ability of a material to prevent the spread of combustion. Additionally, the more flame retardant, the safer the wire.



CSA designation for vertical tray flame test.



Gauge is a term used to denote the physical size of a wire. Additionally, see AWG above.



An object that makes an electrical connection with the earth; a large conducting body (as the earth) used as a common return for an electrical circuit and as an arbitrary zero potential; synonym for “earth”. Specifically, In THHN, the ground is often Green. Additionally, the ground may also be a Bare Copper Conductor.



A Hard Drawn conductor is “work hardened” in the drawing process. Furthermore, Hard drawn refers to the temper of conductors that are not annealed after drawing. Additionally, You will most often hear this term when asked for Hard-Drawn Bare Copper.



A material that shrinks when heated. Heat shrink tubing is used for insulation, sealing, and protecting wire connections, terminations, and splices.



There are many definitions of what high voltage means. It just depends on who you are talking to! First, high voltage can mean a wire or cable with an operating voltage over 600 volts. Second, 5KV through 35KV is coined by many in the electrical industry as “High Voltage”, although its technical term is Medium voltage. Finally, High voltage is actually most accurately any voltage over 35KV. Furthermore, USA represents Hanhe Cable, one of the world’s best high voltage cable manufacturers for HV Utility Type cable.



Hook-Up Wire is usually a wire used for low current, low voltage (under 1,000 volts) applications within enclosed electronic equipment. Typically, usually 12 AWG and smaller is used for Hook-Up Wire. Furthermore, there are also high voltage hook up wire’s that we provide up to 35KV.



Specifically, Impact Strength is the determination of the mechanical punishment a cable can withstand without physical or electrical breakdown. This is important because cable needs to be protected from abuse. Impact Strength is measured by impacting with a given weight, dropped a given distance, in a controlled environment.



Insulation is the portion of a cable which is relied upon to segregate the cable. Also, the insulation protects the conductor from the other conductors, conducting parts, or from ground. Specifically, THHN has Thermoplastic insulation.



A Jumper is usually a temporary connection. Additionally, a jumper cable is a short length of conductor to connect between terminals, across a break in a circuit, or around an instrument. Furthermore, USA sells Jumper cable in red and black most frequently. Usually, a jumper cable will be 5KV or 15KV.



Abbreviation for kilovolt (1,000 volts). One thousand (1,000) volts


Abbreviation for kilovolt ampere (1,000 volt ampere). One thousand (1,000) volts x amperes.



Lay is the length measured along the axis of a wire or cable required for a single strand (in stranded wire) or conductor (in cable) to make one complete turn around the axis of the conductor or cable.



The linear supporting member, usually a high strength steel wire, used as the supporting element of a suspended aerial cable. Additionally, the messenger may be an integral part of the cable or exterior to it.



Military cable specification.



Abbreviation for military specification.


Abbreviation for military standard.


Military wire specification.


Min is the Abbreviation for “minimum”. Furthermore, You will often hear it stated during the quoting process if an item has a Minimum order quantity. Specifically, “What’s the Min.”?



Abbreviation for Mining Safety and Health Administration.



Abbreviation for machine tool wire, plastic insulated, 600 volt, varies 90° C to 105° C.



Abbreviation for National Electric Code.



Abbreviation for National Electrical Manufacturers Association. Additionally, NEMA Maintains standardization of electrical motors, gear reducers, and wire and cable specifications.



Abbreviation for outside diameter. Specifically, you will hear your customer ask “What’s the O.D.”. Now you know.



A Pair is two insulated wires of a single circuit associated together.



A.) Two insulated conductors in parallel in a cable.  B.) Specifically, in THHN your customer will ask you for a “Parallel”, meaning multiple colors or sizes are reeled together on one reel, making the “Pull” easier for the installer.



A put up is the packaging of finished wire or cable. Additionally, we discovered above that typical put ups for THHN are 500 feet, 1000 feet, 2500 feet, and 5000 feet.



Important to note, a family of insulating compounds whose basic ingredient is either polyvinyl chloride or its copolymer with vinyl acetate, in combination with appropriate plasticizers, stabilizers, fillers, and pigments. Additionally, Like many other plastic materials, these insulations can be compounded to provide a wide variety of properties for various applications. Furthermore, among the properties obtained are resistance to moisture, cold, heat, flame, oils, solvents, chemicals, and ozone. Electrical properties are adequate for low voltage power applications. Specifically, Temperature ratings up to 105° C are recognized by UL for certain applications. Also, These insulations are widely used for types T and TW building wires, series street lighting cable, machine tool wiring, hook-up and appliance wiring, overhead line wire, control and signal cables, and many others. Known as PVC or Vinyl. Abbreviation PVC.



A four conductor cable. Additionally, “Quad” is short for Quadruplex.



A Reel is a Circular container on which wire is wound for storage or transit, usually made of wood or metal. Additionally, reels may be constructed of plastic or fiber. The most common reel type for THHN is Wood reels, do to their low cost.



To rerun material from one package spool to another for various purposes, such as, to verify lengths, inspect for defects, or to a specified packaging from our customer.



First, RHW is 75° C rubber insulated Cable type. RHW also has Heat and moisture resistant insulation with an outer cover of moisture resistant, flame-retardant, and a nonmetallic covering. Because of this, RHW is generally used in wet locations.



In cables, a metallic layer is placed around a conductor or group of conductors to prevent electrostatic or electromagnetic interference between the enclosed wires and external fields.


Shield Coverage is the physical area of a cable that is actually covered by the shielding material and is expressed in percent. You won’t be dealing with shields on your standard THHN Wire, but when you get into THHN Tray and Control cable you will deal with shields.



An insulated conductor which has been shielded by a copper braid or tape, aluminum foil, copper foil, or a semi-conductive vinyl. The purpose is to confine the electrical field.



A cable with multiple conductors with a metallic or nonmetallic shield over the cable core, or over each individual shield. Additionally, you may have a cable that is both individual and overall shielded.



Short lengths. Additionally known as remnants. Often less than standard lengths of wire or cable which are generated by making cuts for special orders. Furthermore, These shorts are often sold at a discount making it all the more important for the factory to charge cutting charges in order to make up some of the waste from all the shorts.



The maximum temperature at which an insulating material may be used in continuous operation without loss of its basic properties.



Building wire, plastic insulated, 90° C, 600 volt, nylon jacket. Used in dry locations. The point of this entire page. I only posted this for you to scratch your head…



Building wire, plastic insulated, heat, flame, and moisture resistant, 75° C.



Same as THW with overall nylon jacket. Specifically, used in dry and wet locations.



Tin coating added to a copper conductor or braid to aid in soldering and inhibit corrosion. Specifically, Abbreviated as TC.



When color coding is accomplished by more than one stripe on the same wire. Furthermore, The first stripe, or widest, is called the base stripe, the others, usually narrower, are called tracer stripes. Finally, striping can be made easy!



A group of three insulated conductors twisted and/or sheathed or held together mechanically. Usually, a Triplex is color coded or ridge marked. Additionally, this is also called triad.




Abbreviation for Underwriters Laboratories Inc. Furthermore, UL is a nonprofit organization that maintains and operates laboratories for the examination and testing of devices, systems and materials relative to life, fire and casualty, hazards, and crime prevention. Moreover, UL was founded in 1894, the enterprise is sponsored by the National Board of Fire Underwriters. Additionally, many other NRTL organizations can test and certify to UL safety standards. Furthermore, please contact us if you need more information on UL.


A product that has been tested and approved to Underwriters Laboratories standards.



Vertical flame test for wire and cable. Specifically, VW-1 is a standard established by Underwriters Laboratories. Finally, VW-1 is Formerly known as FR-1.



Wall thickness refers to insulation thickness or jacket thickness that has been applied. Moreover, “Wall” is the sheath’s thickness and is often listed in millimeters or inches.



A slender rod or filament of drawn metal. Furthermore, The term “Wire” is a generally used one, which may refer to any single conductor. If larger than 9 AWG or multiple conductors, it is usually referred to as a cable. However, you will find that throughout the electrical industry Wire & Cable are two interchangable words. For example, the title of this article says “THHN Wire”, but we have covered THHN cable as well.



Cross-linked polyethylene insulated, rated at 90° C in dry locations and 75° C in wet locations.