A cable marked “THHN” may look almost identical to one marked “THHN/THWN-2,” but the two markings do not give buyers the same installation rights.
One may be suitable only where a dry-location rating is acceptable. The other may be rated for both wet and dry locations at 90°C. A wire may also carry additional markings for oil resistance, gasoline resistance, sunlight resistance, machine-tool wiring, or cable-tray use—but these properties should never be assumed from the nylon covering alone.
For importers, distributors, contractors, and project buyers, specifying UL 83 THHN wire therefore requires more than confirming the conductor size and price.
You should verify:
- The exact UL type designation
- The 600V voltage rating
- Dry- and wet-location temperature ratings
- Copper or aluminium conductor construction
- PVC insulation and nylon covering
- UL certification status
- Surface markings and packaging labels
- Electrical and dimensional test results
- Reel length, color, tolerances, and shipment consistency
This guide explains how the UL 83 wire standard applies to THHN and THWN-2 building wire, what the markings mean, and what buyers should inspect before approving a sample or bulk order.
Quick Answer: What Is UL 83 THHN/THWN-2 Wire?
UL 83 is the North American standard covering specified types of 600V single-conductor thermoplastic-insulated wire and cable.
THHN/THWN-2 is normally a single insulated conductor consisting of:
- A solid or stranded conductor
- Heat- and moisture-resistant thermoplastic insulation, commonly PVC
- A thin nylon outer covering
The two type designations provide different environmental ratings:
| Designation | Dry-location rating | Wet-location rating | Nominal voltage | Main distinction |
|---|---|---|---|---|
| THHN | 90°C | Not assigned a wet rating | 600V | High-heat thermoplastic wire with nylon covering |
| THWN | 75°C | 75°C | 600V | Moisture-resistant thermoplastic wire |
| THWN-2 | 90°C | 90°C | 600V | Maintains its 90°C rating in wet and dry locations |
| THHN/THWN-2 | 90°C | 90°C under its THWN-2 rating | 600V | Dual-rated product for broader installation conditions |
The official UL wire and cable marking guide identifies THHN as a 90°C dry-location wire and THWN-2 as a 90°C wet- and dry-location wire.
Most buyers now specify dual-rated THHN/THWN-2 cable because it reduces inventory complexity and allows the same product to be used in more conduit and raceway environments. However, the dual rating must appear in the product certification and marking; it should not be assumed merely because the wire has a PVC-and-nylon construction.
For a detailed application comparison, see our THHN vs THWN-2 wire guide.
What Does the UL 83 Standard Cover?
The active UL 83 standard is titled Thermoplastic-Insulated Wires and Cables.
Its scope covers designated 600V single-conductor thermoplastic-insulated wires for use under the applicable electrical codes in:
- The United States
- Canada
- Mexico
The UL Standards page currently identifies UL 83 Edition 16 as active and shows a latest revision date of October 23, 2025. Buyers should therefore state the required standard edition or request confirmation that the offered product remains covered by an active certification record.
UL 83 addresses product construction, materials, dimensions, electrical characteristics, environmental performance, markings, and other safety requirements applicable to the wire type.
However, UL 83 is not a complete installation design manual.
It does not replace:
- The National Electrical Code or another local wiring code
- Project cable schedules
- Ampacity calculations
- Conduit-fill calculations
- Voltage-drop calculations
- Terminal temperature limitations
- Local certification and inspection requirements
A product can be manufactured to a UL 83 construction while still being unsuitable for a particular installation environment. The project designer must confirm both product compliance and installation suitability.
UL 83, the NEC, and UL Certification Are Not the Same Thing
These three terms are related, but they perform different functions.
UL 83 Defines Product Requirements
UL 83 establishes technical requirements for thermoplastic-insulated wire types such as THHN and THWN-2.
It deals with the characteristics of the wire itself, including its construction, ratings, materials, performance, and identification.
The NEC Controls How the Wire Is Used
The National Electrical Code determines where and how a listed conductor may be installed in the United States.
The NEC addresses matters such as:
- Permitted wiring methods
- Wet, dry, and other installation locations
- Conductor ampacity
- Ambient-temperature correction
- Adjustment for multiple current-carrying conductors
- Conduit and raceway use
- Terminal temperature ratings
- Overcurrent protection
A 90°C insulation rating does not automatically mean that the conductor can always carry the ampacity shown in a 90°C column. Equipment terminals, conductor size, installation conditions, ambient temperature, and applicable code rules can limit the final allowable ampacity.
UL Certification Identifies Evaluated Products
A supplier saying “made according to UL 83” is not the same as providing an actively UL-certified product.
For a certification-based order, buyers should verify:
- Certification holder
- UL file number
- Product category
- Covered wire types
- Conductor sizes
- Materials and ratings
- Factory location where relevant
- Current certification status
UL Product iQ allows users to search certification information by details such as file number, company, model number, and product category.
What Do THHN and THWN-2 Mean?
The type letters summarize important construction and performance characteristics.
THHN Meaning
THHN generally means:
- T — Thermoplastic insulation
- HH — 90°C high-heat rating
- N — Nylon covering
The UL marking guide identifies “T” as thermoplastic insulation, “HH” as 90°C, “N” as a nylon jacket or covering, and “W” as moisture resistant.
THWN-2 Meaning
THWN-2 is commonly understood as:
- T — Thermoplastic insulation
- H — Heat resistant
- W — Moisture resistant
- N — Nylon covering
- -2 — 90°C rating in both wet and dry locations
The “W” and “-2” are particularly important for outdoor or underground raceway projects because water and condensation can enter conduit systems even when the conductors are not directly exposed to rain.
Why Dual Marking Matters
A dual-rated wire may be printed as:
THHN OR THWN-2 600V
In a dry installation, it may be applied under its THHN rating. In a wet location, its THWN-2 designation provides the required wet-location rating.
The cable does not physically change between applications. The combined marking shows that the same construction has been evaluated for both designations.
Typical UL 83 THHN/THWN-2 Wire Construction

Although formulations and conductor options vary by manufacturer, a conventional THHN/THWN-2 wire has three main layers.
1. Copper or Aluminium Conductor
The conductor carries the electrical current.
Common options include:
- Solid annealed copper
- Stranded annealed copper
- Compressed or compact stranded copper for certain sizes
- Aluminium alloy conductor where covered by the product design and certification
Copper remains common for residential, commercial, industrial, and control-circuit wiring because of its conductivity, termination familiarity, and relatively small conductor size for a given circuit requirement.
Aluminium may be selected for larger feeders where weight and material cost are important, but it requires compatible terminals, correct preparation, suitable conductor alloy, and project approval.
Buyers should not accept the words “copper conductor” as a complete specification. The RFQ should state:
- Bare or tinned conductor
- Copper or aluminium
- Solid or stranded
- Required AWG or kcmil size
- Number and diameter of strands
- Compact, compressed, or concentric construction where required
- Maximum conductor resistance
2. Thermoplastic Insulation
The conductor is covered with heat-resistant thermoplastic insulation, most commonly a specially formulated PVC compound.
The insulation provides:
- Primary electrical isolation
- Heat resistance
- Moisture resistance for the applicable designation
- Flame performance
- Resistance to normal installation and service stresses
The compound used for dual-rated THHN/THWN-2 must support both the high-temperature and wet-location performance required by the type designations.
For a broader explanation of PVC formulation and performance, see our guide to PVC compound for wire and cable.
3. Nylon Outer Covering
A thin nylon layer is extruded over the PVC insulation.
Its main purposes include:
- Protecting the PVC surface during pulling
- Improving abrasion resistance
- Reducing pulling friction
- Providing additional resistance to certain oils and chemicals when the complete product is appropriately rated
- Creating a smooth, compact outer surface
The nylon layer should not be treated as a general-purpose mechanical sheath.
It does not automatically make the wire:
- Suitable for direct burial
- Sunlight resistant
- Suitable for exposed outdoor installation
- Oil resistant at every temperature
- Suitable for cable trays
- A substitute for armoured or jacketed cable
These properties must be confirmed through the exact product markings, data sheet, certification scope, and installation code.
A major North American manufacturer describes its 600V THHN/THWN-2 construction as a copper conductor with heat- and moisture-resistant PVC insulation and a nylon sheath, illustrating the standard market construction.
THHN, THWN, and THWN-2 Temperature Ratings
Temperature markings are among the most frequently misunderstood parts of a THHN specification.
THHN
THHN is rated:
- 90°C in dry locations
- No general wet-location rating under the THHN designation
A standalone THHN marking should therefore not be treated as proof of suitability for a wet location.
THWN
Traditional THWN is normally rated:
- 75°C in dry locations
- 75°C in wet locations
THWN-2
THWN-2 is rated:
- 90°C in dry locations
- 90°C in wet locations
Oil and Gasoline Exposure
A wire may have a lower permitted temperature when exposed to oil or gasoline.
For example, a product may be marked with an oil- or gasoline-resistance designation that permits use at 75°C under those exposure conditions. Buyers must check the actual legend and data sheet rather than assuming that the general 90°C rating applies to every chemical environment. Southwire, for example, lists its THWN-2 wire at 90°C wet or dry and 75°C where exposed to oil.
Does a 90°C Rating Determine the Wire Ampacity?
No.
The 90°C rating identifies the temperature capability of the insulation under the applicable designation. It does not independently establish the final allowable current for every circuit.
Ampacity selection may also depend on:
- Conductor material
- AWG or kcmil size
- Number of current-carrying conductors
- Ambient temperature
- Raceway arrangement
- Terminal temperature rating
- Overcurrent protection
- Local electrical code
- Equipment listing
- Harmonic loading
- Installation method
The 90°C insulation rating may be useful when applying correction or adjustment factors, but the final conductor ampacity can still be limited by 60°C or 75°C terminations.
For this reason, a purchase order should specify the conductor size required by the approved engineering design rather than asking a supplier to select a size solely from a generic online ampacity chart.
Is UL 83 THHN/THWN-2 a 600V Building Wire?
Yes. THHN and THWN-2 covered by UL 83 are commonly rated 600V.
Typical applications include protected single-conductor wiring for:
- Services
- Feeders
- Branch circuits
- Distribution panels
- Commercial buildings
- Industrial facilities
- Lighting circuits
- HVAC supply circuits
- Control cabinets
- Machinery connections when the necessary additional standards or markings apply
- Conduit and approved raceway systems
UL 83 officially describes its main scope as 600V single-conductor thermoplastic-insulated wires and cables.
However, 600V should not be confused with the European or IEC designation 0.6/1kV.
A UL 83 600V building wire and an IEC 60502-1 0.6/1kV power cable belong to different standard systems and often have different constructions, voltage designations, installation methods, markings, and approval requirements.
Where Can THHN/THWN-2 Wire Be Used?
Indoor Conduit and Raceway
THHN/THWN-2 is widely used as an individual conductor pulled through:
- Electrical metallic tubing
- Rigid metal conduit
- PVC conduit
- Wireways
- Approved raceways
The smooth nylon surface helps reduce damage and friction during installation.
Outdoor or Underground Conduit
Outdoor and underground conduits can contain condensation or water.
For these applications, the conductor should carry a suitable wet-location rating such as THWN-2. A standalone THHN marking is not sufficient proof of wet-location suitability.
The wire still needs an approved raceway unless the specific product and installation method permit otherwise.
Commercial and Industrial Distribution
Dual-rated 600V building wire is commonly used for:
- Panel feeders
- Lighting circuits
- Receptacle circuits
- Motor circuits
- HVAC equipment
- Factory distribution
- Building services
Final conductor sizing and installation must follow the applicable electrical design and code.
Control Panels and Machine Tools
Some products carry additional designations such as MTW or AWM.
These markings are governed by other standards and applications. A THHN marking alone does not automatically confirm that the product is approved as machine-tool wire or appliance wiring material.
Where Should THHN/THWN-2 Not Be Used Automatically?
Direct Burial Without an Approved Rating
A THWN-2 wet-location rating does not automatically mean that an individual conductor can be buried directly in soil.
Direct burial exposes wire to:
- Soil pressure
- Stones and mechanical damage
- Water
- Chemicals
- Installation impact
- Long-term environmental stress
Use a specifically approved direct-burial construction or install the conductor in the required raceway system.
Exposed Outdoor Installation Without Sunlight Resistance
A nylon covering does not automatically provide long-term UV resistance.
Where the conductor is exposed to sunlight, confirm a suitable sunlight-resistant marking and the permitted wiring method.
Flexible Cord Applications
THHN/THWN-2 is building wire, not portable flexible cord.
It should not automatically replace products designed for:
- Extension cords
- Portable appliances
- Repeated flexing
- Dragging
- Mobile machinery
- Temporary power cords
Residential In-Wall Wiring Without Raceway
Individual THHN/THWN-2 conductors are normally installed in an approved raceway or wiring system.
For dry interior residential branch circuits where the local code permits a complete non-metallic cable assembly, buyers may instead evaluate NM-B cable.
What Performance Should a Buyer Confirm?
The complete UL 83 standard contains detailed requirements that must be evaluated according to the product designation and construction. From a buyer’s perspective, the following areas should be covered by certification records, factory controls, or agreed test documentation.
Conductor Dimensions and Resistance
Confirm:
- Conductor material
- AWG or kcmil size
- Strand count
- Strand diameter
- Overall conductor diameter
- DC conductor resistance
Undersized conductors may reduce material cost but increase resistance, voltage drop, heat generation, and compliance risk.
Insulation and Nylon Dimensions
Confirm:
- Minimum insulation thickness
- Average insulation thickness where applicable
- Minimum nylon thickness
- Finished outer diameter
- Concentricity
- Surface condition
Excessively thin insulation or nylon may lead to weak dielectric performance, pinholes, abrasion damage, or inconsistent pulling behavior.
Electrical Integrity
Relevant factory checks may include:
- Spark testing during production
- Voltage withstand testing
- Insulation integrity
- Conductor resistance
- Continuity
Buyers should request actual test values instead of accepting a report that only says “PASS.”
Heat and Aging Performance
The thermoplastic insulation must remain suitable under its rated thermal conditions.
Evaluation may cover:
- Heat aging
- Tensile and elongation retention
- Thermal deformation
- Heat shock
- Long-term material stability
Moisture Performance
For THWN and THWN-2 products, wet-location performance is an essential part of the designation.
The buyer should confirm that the offered certification record specifically includes THWN-2 rather than relying on a supplier’s statement that the PVC is “waterproof.”
Flame and Environmental Properties
Depending on the product and its optional markings, evaluation may address:
- Flame propagation
- Oil resistance
- Gasoline resistance
- Sunlight resistance
- Cold bending
- Abrasion
- Mechanical handling
UL explains that wire and cable evaluations can include electrical properties, materials and construction, environmental exposure, and flammability, depending on the product and intended installation.
How to Read a THHN/THWN-2 Wire Marking
A typical wire legend may contain information similar to:
MANUFACTURER 12 AWG CU TYPE THHN OR THWN-2 600V 90°C DRY AND WET UL FILE NO. XXXXX
The exact format varies, but buyers should look for the following information.
| Marking item | What it tells the buyer |
|---|---|
| Manufacturer or trademark | Identifies the certified producer or brand |
| Conductor size | AWG or kcmil size |
| Conductor material | Copper, aluminium, or another specifically approved material |
| Type designation | THHN, THWN, THWN-2, or combined ratings |
| Voltage | Normally 600V |
| Temperature | Dry, wet, or exposure-specific rating |
| Optional properties | Oil, gasoline, sunlight, tray, flame, or other evaluated properties |
| Certification identification | Information used to trace the product certification |
Do not judge compliance from the printed word “UL” alone.
UL’s wire and cable marking guide explains that the UL Mark applied to the coil, reel, flange, or box is the primary means of identifying wire and cable covered by UL certification and Follow-Up Service. Surface-printed “UL” letters are supplemental and should not by themselves be treated as evidence of certification coverage.
This distinction is extremely important for imported bulk wire.
12 Buyer Checks Before Ordering UL 83 Wire

1. Confirm the Exact Type Designation
Write the complete requirement:
UL 83 THHN/THWN-2, 600V, 90°C wet and dry
Do not simply write “THHN cable.”
2. Verify the UL Certification Record
Search the manufacturer or UL file number in UL Product iQ.
Confirm that:
- The record is active
- The company name matches
- The factory or certification holder is correct
- THHN and THWN-2 are covered
- The requested conductor material and size range are included
3. Match the Manufacturer, Trader, and Certificate Holder
A trading company may sell wire produced by another factory.
Clarify:
- Who manufactures the wire
- Who owns the UL file
- Which factory appears in the certification record
- Which name will appear on the reel label
- Which brand will appear on the wire
4. Confirm Conductor Material
State whether you require:
- Bare copper
- Tinned copper
- Aluminium
- Copper-clad aluminium, if permitted and specifically accepted
Do not allow an unapproved conductor substitution.
5. Confirm Size and Stranding
Specify:
- AWG or kcmil size
- Solid or stranded
- Strand count
- Strand diameter
- Compact or compressed construction if required
A nominal size without strand details may not be sufficient for termination and installation planning.
6. Request Dimensional Data
The technical data sheet should state:
- Conductor diameter
- Insulation thickness
- Nylon thickness
- Finished outside diameter
- Approximate net weight
These values help buyers compare quotations and check production consistency.
7. Request Conductor Resistance Results
Ask for:
- Standard limit
- Measured value
- Test temperature
- Conversion method where applicable
- Batch or sample identification
Conductor resistance is one of the most useful checks for identifying undersized or inconsistent conductors.
8. Confirm Optional Ratings Separately
Specify optional requirements only when the project needs them, such as:
- Oil resistance
- Gasoline resistance
- Sunlight resistance
- VW-1 flame rating
- Cable-tray rating
- MTW
- AWM
- RoHS
- REACH
- Low-temperature performance
Do not assume these properties are included in every UL 83 product.
9. Approve the Surface Printing
Request a print artwork showing:
- Manufacturer or brand
- Wire size
- Conductor material
- Type designation
- Voltage
- Temperature ratings
- UL-related identification
- Production code or traceability information
- Meter or foot marking if required
10. Inspect Packaging and UL Labels
Confirm:
- Coil, spool, reel, or drum type
- Length per package
- Length tolerance
- Label design
- Batch number
- Production date
- Gross and net weight
- UL certification label arrangement
- Export carton or pallet requirements
11. Test a Preproduction Sample
Before a large order, inspect:
- Conductor size
- Strand construction
- Resistance
- Insulation thickness
- Nylon thickness
- Outer diameter
- Color
- Printing
- Flexibility
- Surface quality
- Package length
12. Define Final Inspection Requirements
The purchase contract should state whether inspection will include:
- Factory test report review
- Random dimensional measurement
- Conductor resistance testing
- Spark-test records
- Length verification
- Label verification
- Packaging inspection
- Third-party inspection
- Retained reference samples
For additional supplier-audit points, read our guide on choosing a cable manufacturer in China.
Common THHN/THWN-2 Purchasing Red Flags
| Red flag | Why it matters |
|---|---|
| Supplier only says “UL standard” | May mean construction-based production rather than active UL certification |
| No UL file number is provided | Certification cannot be independently verified |
| File belongs to an unrelated company | Product source and certification scope may not match |
| Only “THHN” appears on the wire | Wet-location THWN-2 rating may not be covered |
| Copper weight is unusually low | The conductor may be undersized |
| No conductor resistance data | Electrical performance cannot be properly compared |
| No insulation or nylon dimensions | Material reduction may be hidden |
| “Waterproof” is used instead of THWN-2 | Marketing language does not replace a type designation |
| Sunlight resistance is assumed from nylon | UV suitability must be separately confirmed |
| UL is printed on the wire but packaging has no proper label | Surface printing alone is not sufficient certification evidence |
| Report contains only PASS/FAIL | Buyers cannot compare actual production values |
| Spool length has no tolerance | Short-length delivery disputes may occur |
| Sample and production legends differ | The approved sample may not represent the shipped product |
THHN/THWN-2 vs Other Building Wire Types
THHN/THWN-2 vs XHHW-2
| Feature | THHN/THWN-2 | XHHW-2 |
|---|---|---|
| Insulation family | Thermoplastic PVC with nylon covering | Thermoset cross-linked insulation |
| Voltage | Commonly 600V | Commonly 600V; some constructions may have other ratings |
| Wet/dry temperature | 90°C under THWN-2 rating | 90°C wet and dry |
| Physical profile | Often thinner and smooth for conduit pulling | Often thicker and more robust |
| Typical selection reason | Compact, economical building wire | Greater environmental and insulation robustness |
The final choice should be based on specification, raceway conditions, conductor size, pulling requirements, and local code—not only unit price.
THHN/THWN-2 vs NM-B
| Feature | THHN/THWN-2 | NM-B |
|---|---|---|
| Form | Individual single conductors | Complete multi-conductor cable assembly |
| Installation | Normally in conduit or approved raceway | Commonly installed in dry interior residential spaces where permitted |
| Wet-location suitability | Yes under THWN-2 designation | No |
| Typical market | Commercial, industrial, residential conduit systems | Residential branch circuits |
| Mechanical protection | Provided mainly by raceway | Provided by the cable assembly and installation method |
THHN/THWN-2 vs IEC Building Wire
UL 83 products should not automatically be substituted with IEC-designated wires such as H07V-U or H07V-K.
Differences may include:
- Voltage designation
- Conductor classes
- Insulation dimensions
- Approval marks
- Fire testing
- Color identification
- Installation codes
- Market acceptance
For an overview of European-style options, see our building wire types guide.
Sample RFQ for UL 83 THHN/THWN-2 Wire
Buyers can use the following template when requesting a quotation:
Product Standard
- UL 83, active certified construction
- Type THHN/THWN-2
- Rated voltage: 600V
- Temperature rating: 90°C wet and dry
Conductor
- Material: Bare annealed copper
- Size: ___ AWG / ___ kcmil
- Construction: Solid / stranded
- Strand count and diameter: ___
- Maximum DC resistance: ___
Insulation and Covering
- Primary insulation: Heat- and moisture-resistant PVC
- Outer covering: Nylon
- Minimum insulation thickness: ___
- Minimum nylon thickness: ___
- Maximum finished diameter: ___
Additional Ratings
- Oil resistance: Required / not required
- Gasoline resistance: Required / not required
- Sunlight resistance: Required / not required
- VW-1: Required / not required
- MTW or AWM: Required / not required
- RoHS or REACH: Required / not required
Identification
- Wire color: ___
- Printing content: ___
- Sequential length marking: Required / not required
- Private label: Required / not required
Packaging
- Coil, spool, reel, or drum: ___
- Length per package: ___
- Length tolerance: ___
- Export carton or pallet: ___
- Label artwork approval required before production
Documentation
- UL file number
- Product iQ certification record
- Technical data sheet
- Certificate of conformity
- Batch test report
- Conductor resistance report
- Dimensional report
- Packing list
- Country-of-origin document where required
Inspection
- Preproduction sample required
- Final random inspection
- Length verification
- Resistance testing
- Marking and UL label verification
- Third-party inspection where required
Frequently Asked Questions
Is THHN wire waterproof?
Not automatically.
Standalone THHN is identified as a 90°C dry-location wire. A product must carry a suitable wet-location designation such as THWN or THWN-2 where that rating is required.
Is THHN/THWN-2 rated for 600V?
Yes. UL 83 covers specified 600V single-conductor thermoplastic-insulated wires, and THHN/THWN-2 is commonly supplied as 600V building wire.
Can THHN be installed in underground conduit?
The conductor used in an underground conduit should carry an appropriate wet-location rating because water or condensation may be present.
A dual-rated THHN/THWN-2 conductor may be suitable under its THWN-2 designation, subject to the approved wiring method and local code.
Can THWN-2 be directly buried?
A wet-location rating does not automatically establish direct-burial approval.
Check the complete product marking, certification scope, cable construction, and installation code before burying any conductor directly in soil.
Does the nylon layer provide the electrical insulation?
The PVC or other thermoplastic layer is the primary electrical insulation. The nylon layer mainly provides a smooth, abrasion-resistant protective covering and supports other evaluated performance characteristics.
Is all THHN wire also THWN-2?
No.
Many modern products are dual-rated, but buyers must verify the actual type marking and certification record. Never assume that every wire sold as “THHN” carries a THWN-2 wet-location rating.
Does 90°C wire always use the 90°C ampacity?
No.
The final allowable ampacity may be limited by terminal ratings, conductor size, ambient temperature, bundling, overcurrent protection, equipment requirements, and local electrical code.
Is UL 83 the same as UL 1063?
No.
UL 83 covers thermoplastic-insulated wire types for general wiring, while UL 1063 applies to machine-tool wire. A product may carry both designations if it has been evaluated for both, but one marking should not be assumed from the other.
How can buyers verify that a UL certificate is genuine?
Use the UL Product iQ database to search the file number, manufacturer, product category, and covered product information. Also check the UL certification label on the coil, reel, flange, box, or other approved packaging—not only the letters printed on the wire surface.
Final Buyer Recommendation
UL 83 provides the technical foundation for THHN, THWN, and THWN-2 thermoplastic-insulated building wire, but the words “UL 83 wire” are not a complete purchase specification.
Before placing a bulk order, confirm:
- Exact THHN, THWN, or THWN-2 designation
- Active UL certification record
- Certification holder and manufacturing source
- Copper or aluminium conductor
- AWG or kcmil size
- Solid or stranded construction
- Conductor resistance
- PVC insulation and nylon dimensions
- Dry- and wet-location ratings
- Oil, gasoline, sunlight, flame, or other optional ratings
- Surface marking and traceability
- UL packaging labels
- Coil or reel length
- Batch test documentation
- Sample and final inspection requirements
KingForYou Cable supplies THHN/THWN building wire, NM-B cable, T90 nylon wire, IEC building wire, and other low-voltage cable products for distributors, contractors, OEM buyers, and project procurement.
For a technical quotation, send your required standard, conductor material, AWG or kcmil size, color, quantity, package length, target market, certification requirements, and inspection documents through our contact page.






