How to Read UL Wire Markings and AWM Wire Ratings
Learn how to read AWM Style, AWG, voltage, temperature and VW-1 markings—and what still needs to be verified before wire is released for an OEM wiring or wire-harness project.
A representative AWM wire marking may look like E###### · AWM STYLE 1015 · 18 AWG · 600V · 105°C · VW-1. The marking can identify the applicable AWM construction, conductor gauge, voltage rating, temperature rating and, where authorized, a flame-performance designation such as VW-1. But surface printing is not a complete engineering or certification record: finished OD, strand construction, application ampacity, terminal compatibility and current product verification may still need to be checked separately.
Read the Marking in Layers
Each part answers a different engineering or identification question.
Key Takeaways
One printed line can contain several different kinds of wire information.
AWM identifies the Appliance Wiring Material category, not one universal wire construction.
An AWM Style identifies a more specific construction within the AWM system.
AWG identifies conductor gauge, but does not by itself define finished wire OD.
300V / 600V and 80°C / 105°C are separate wire ratings, not a complete project specification.
VW-1 is a flame-performance designation where the specific product has been evaluated and authorized for that marking.
Surface printing supports identification; controlled verification also uses reel/tag, product data and current certification information.
01 · Marking Anatomy
How to Read an AWM Wire Marking
Start with a representative example:
E###### · AWM STYLE 1015 · 18 AWG · 600V · 105°C · VW-1
Although these items appear in one continuous line, they describe different parts of the wire.
| Marking | What It Tells You | What It Does Not Tell You |
|---|---|---|
| E###### | UL file number / manufacturer traceability, where present | Complete product suitability |
| AWM | Appliance Wiring Material category | Exact wire construction |
| STYLE 1015 | AWM construction designation | Complete project specification |
| 18 AWG | Conductor gauge | Exact finished wire OD |
| 600V | Voltage rating | Suitability for every 600 V application |
| 105°C | Temperature rating | Rating of the complete harness or equipment |
| VW-1 | Flame-performance designation | Insulation material or wire Style |
Read the marking as separate layers of information: identification → AWM category and Style → conductor size → electrical rating → thermal rating → additional performance marking.
02 · Classification
What Does “AWM” Mean on a Wire?
AWM stands for Appliance Wiring Material.
UL 758 covers AWM constructions intended primarily for factory-installed wiring inside equipment, external interconnecting cable for equipment or further processing into cable constructions.
AWM tells you the component-wiring category. It does not identify one complete or universal wire construction.
The more specific construction is normally identified through the applicable AWM Style and manufacturer product information.
What Is AWM Wire? Appliance Wiring Material Explained Use the dedicated AWM guide for the broader system, terminology and Style structure. →03 · Construction
What Does an AWM Style Number Mean?
A marking such as AWM STYLE 1015 identifies a particular construction within the AWM system.
Style 1007, Style 1015 and Style 1061 are examples of AWM Styles. Different Styles can have different construction, rating and use requirements.
AWM = category. AWM Style = more specific construction.
Detailed differences between individual Styles belong in the dedicated Style-comparison article rather than being repeated here.
UL 1007 vs UL 1015 vs UL 1061 Wire Compare three commonly specified AWM Styles by ratings, construction and OEM fit. →04 · AWM Wire Rating
What Does an AWM Wire Rating Tell You?
The phrase AWM wire rating should not be treated as one single number.
Several characteristics may appear together on the same wire or product documentation.
| Rating / Marking | What It Describes |
|---|---|
| AWM Style | Construction definition |
| AWG | Conductor gauge |
| Voltage | Applicable voltage rating |
| Temperature | Applicable temperature rating |
| VW-1 | Applicable flame-performance marking |
| Other identification | Manufacturer, file or other product information where present |
The same AWG does not guarantee the same insulation construction. The same voltage rating does not guarantee the same Style. A higher printed rating does not automatically make one wire an approved substitute for another.
Read an AWM wire rating as part of a defined construction—not as a shortcut for deciding whether a wire fits a project.
05 · Gauge & Size
How to Read AWM Wire Gauge and Size
A marking such as 18 AWG identifies conductor gauge.
It does not identify the finished outside diameter of the insulated wire.
Two 18 AWG AWM wires may have different finished diameters because wire OD can also depend on conductor construction, strand configuration, insulation material, insulation thickness, AWM Style and manufacturer-specific dimensions.
That difference can affect terminal insulation support, connector seals, rear cavities, grommets, stripping settings, sleeving, routing and total bundle size.
For sourcing, wire gauge should be reviewed together with the required AWM Style, insulation, ratings and finished dimensions. See UL Hook-Up Wire for the specification fields commonly reviewed in OEM internal-wiring projects.
AWM Wire Gauge Chart: What AWG Actually Tells You
| Example | What You Know | What You Do Not Know Yet |
|---|---|---|
| 26 AWG | Conductor gauge | Style, finished OD, ratings, strand construction |
| 22 AWG | Conductor gauge | Style, finished OD, ratings, strand construction |
| 18 AWG | Conductor gauge | Style, finished OD, ratings, strand construction |
| 16 AWG | Conductor gauge | Style, finished OD, ratings, strand construction |
An AWM wire gauge chart can identify conductor size, but AWG alone should not be treated as a complete AWM wire size specification.
06 · Voltage
How to Read Voltage Ratings on AWM Wire
Common AWM markings can include values such as 30V, 300V or 600V.
If a wire is marked 300V, that number identifies the applicable voltage rating of the wire construction.
Two AWM constructions can share a voltage rating while differing in insulation, temperature rating, finished dimensions or applicable use conditions.
Likewise, a 600 V construction should not automatically replace a 300 V construction merely because the printed number is higher.
For an OEM project, the useful question remains: does the actual wire construction match the approved electrical, mechanical and end-product requirements?
07 · Temperature
What Does 105°C Mean on a Wire?
A marking such as 105°C describes the applicable temperature rating of the wire construction.
It does not mean every component connected to that wire is also rated for 105°C.
A connector housing, terminal, seal, sleeve or another material in the assembly may have a lower permissible temperature.
Wire temperature rating ≠ complete assembly temperature rating.
In a wire harness, another material or component may become the practical controlling limit.
08 · Insulation
What Does the Marking Tell You About AWM Wire Insulation?
Insulation is an important part of an AWM construction, but the complete insulation description does not have to appear in full on the wire surface.
A wire may display AWM STYLE 1015 · 18 AWG · 600V · 105°C without spelling out every detail of the insulation construction.
Those details may instead be established through the applicable AWM Style, manufacturer datasheet, certification information and controlled project documentation.
AWM wire insulation can affect finished OD, flexibility, stripping behavior, temperature capability, environmental performance, terminal support, seal compatibility and bundle size.
Insulated wire is only one part of the complete harness material system. For terminals, connector housings, splices and protection materials, see Wire Harness Components and Materials: A Complete Guide.
Surface printing helps identify the construction, but manufacturer product data is still needed when dimensional or processing details matter.
09 · Flame Performance
What Does VW-1 Mean on AWM Wire?
A wire marking may include VW-1.
VW-1 is a flame-performance designation. It is not an AWG size, insulation material, AWM Style, voltage rating or temperature rating.
UL Solutions explains that VW-1 marking is used where the specific AWM product complies with the applicable VW-1 requirements and is authorized for that marking.
| Marking | Interpretation |
|---|---|
| Style 1015 | Construction designation |
| 18 AWG | Conductor gauge |
| 600V | Voltage rating |
| 105°C | Temperature rating |
| VW-1 | Flame-performance designation for the applicable evaluated product |
The VW-1 marking belongs to the actual evaluated wire product where applicable. Do not reverse the logic and assume that every product sharing an AWM Style automatically carries VW-1.
10 · Ampacity
Is There a Universal AWM Wire Ampacity Chart?
You cannot safely determine one universal ampacity value from an AWM Style or AWG marking alone.
AWG matters to current-carrying capability, but it is only one input.
| Factor | Why It Matters |
|---|---|
| Conductor gauge | Affects resistance and heat generation |
| Conductor material | Affects electrical resistance |
| Ambient temperature | Changes available thermal margin |
| Bundling | Can reduce heat dissipation |
| Airflow / enclosure | Affects conductor cooling |
| Insulation temperature rating | Provides one thermal constraint |
| Terminal / connector | May become the limiting component |
| Duty cycle | Continuous and intermittent loads heat differently |
| End-product requirements | May impose application-specific limits |
A generic AWG current table is useful only when its assumptions match the real application. It should not automatically be presented as a universal AWM wire ampacity chart.
If the only information available is AWM Style 1015 · 18 AWG, there is still not enough information to responsibly derive one universal application ampacity.
Where current, thermal conditions, terminals, connectors or routing affect wire selection, those requirements should be reviewed together rather than from wire gauge alone. See Design & Engineering Support for the broader project-review context.
11 · Certification Evidence
Wire Printing vs Reel or Tag: Which Should You Use for Verification?
Surface printing is useful for fast identification, but for certification and controlled sourcing it is not the whole picture.
UL's Wire and Cable Application Guide explains that AWM ratings and conditions of acceptability are shown on a tag attached to the reel or carton, while some ratings may also appear on the wire or cable surface.
The same guide explains that the UL Mark on the coil, reel, flange, box or other package is used to identify wire or cable covered under UL certification and Follow-Up Services, while surface printing is supplemental.
Surface Marking
- Fast material identification
- May show Style, AWG and ratings
- Useful during production and inspection
- Not the complete certification record by itself
Reel / Tag / Product Record
- Formal supplied-product identification
- Supports certification verification
- Connects the wire to manufacturer/product information
- Important for controlled sourcing and incoming inspection
Surface marking answers “What wire appears to be in front of me?” Reel, tag and certification records answer “What material was formally supplied and recognized?”
Manufacturer part numbers, approved alternatives and wire specifications should also be controlled consistently in the project BOM. See the BOM Preparation Guide for the component information typically needed before quotation and production.
12 · Production Verification
How to Verify an AWM Wire Before Production
For an OEM project, verification should move from the easiest identification source toward the controlled product record.
The final wire definition should also match the approved project files. The Drawing & Wiring Diagram Guide explains how wire specifications, routing, connection details and revisions can be communicated, while the Internal Wire Harness page shows how selected wire becomes part of a finished OEM wiring assembly.
Reading the wire is the first identification step. Releasing material to production requires the supplied product to match the approved project definition.
13 · Common Mistakes
Common UL Wire Marking Mistakes
Treating AWM as the Complete Wire Type
AWM identifies the category. The Style and actual product provide the more specific construction information.
Reading AWG as Finished Wire Diameter
AWG identifies conductor gauge; insulation and product construction affect final OD.
Assuming 105°C Applies to the Entire Assembly
The wire may carry a 105°C rating while another component in the assembly has a lower limit.
Assuming a Higher Voltage Rating Means Automatic Substitution
A higher printed voltage does not establish construction equivalence or mechanical compatibility.
Treating VW-1 as an Insulation Type
VW-1 is a flame-performance designation, not a polymer description.
Using a Generic AWG Current Table as an AWM Wire Ampacity Chart
Application ampacity still depends on thermal, installation and component conditions.
Treating Surface Printing as the Complete Certification Record
Surface printing helps identify the wire; package identification and current certification information may still need to be verified.
14 · Identification Chart
AWM Wire Marking and Cable Identification Chart
This AWM wire chart focuses on markings and identification within UL AWM component wiring. It is not intended to replace a broader electrical wire types chart covering unrelated UL wire types, building-wire classifications or other cable systems.
| You See | Classification | What It Means | What to Check Next |
|---|---|---|---|
| AWM | Wire classification | Appliance Wiring Material | Applicable Style |
| STYLE 1015 | Construction code | Specific AWM construction | Style/product information |
| 18 AWG | Wire size | Conductor gauge | Stranding and finished OD |
| 300V / 600V | Electrical rating | Applicable voltage rating | Project electrical requirement |
| 80°C / 105°C | Thermal rating | Applicable wire temperature rating | Other component limits |
| VW-1 | Flame performance | Applicable evaluated flame designation | Product/certification information |
| E###### / manufacturer ID | Identification | File / manufacturer traceability where present | Reel/tag/current certification |
This is a more useful way to interpret an AWM cable identification code than trying to force every marking into one universal “wire type.”
15 · Full Example
Read One AWM Wire Marking From Left to Right
E###### · AWM STYLE 1015 · 18 AWG · 600V · 105°C · VW-1
That gives useful identification information, but the marking still does not necessarily tell you the exact finished OD, strand count, full insulation formulation, commercial manufacturer part number, application ampacity, terminal compatibility, seal compatibility, customer approval status or complete current certification record.
Reading the marking is the beginning of material identification—not the end of material verification.
16 · Official References
Official UL References
Certification information and product status can change. For controlled engineering or sourcing decisions, verify the exact product using current UL and manufacturer information.
Conclusion
Read the Marking First—Then Verify the Actual Wire
UL wire markings become much easier to interpret once each field is treated according to what it actually describes.
The key is not to ask one marking to answer a question it was never intended to answer.
AWG does not give you finished OD. A temperature rating does not rate the entire harness. VW-1 does not identify the insulation material. And an AWM Style or gauge alone does not establish a universal ampacity.
Read the marking → identify the construction → verify the supplied product → confirm it against the approved project specification.
This keeps the AWM wire rating useful as an identification tool without confusing it with the complete engineering, sourcing and certification record.
Frequently Asked Questions
AWM Wire Markings and Ratings FAQ
Quick answers about AWM wire ratings, gauge, voltage, temperature, VW-1, ampacity and certification verification.
What is an AWM wire rating?
An AWM wire rating describes characteristics associated with the applicable Appliance Wiring Material construction, which may include voltage, temperature and other performance information. The complete interpretation also depends on the applicable AWM Style and actual manufacturer product.
What does AWM mean on wire?
AWM means Appliance Wiring Material. UL 758 covers AWM intended primarily as factory-installed component wiring, external equipment interconnection or material for further cable construction.
What does 300V mean on AWM wire?
It is the applicable voltage rating of that wire construction. It does not mean all 300V AWM constructions are identical or interchangeable.
What does 105°C mean on wire?
It indicates the applicable temperature rating of the wire construction. The complete assembly may still be limited by connectors, terminals, seals or other components.
What does VW-1 mean on AWM wire?
VW-1 is a flame-performance designation. It applies where the specific AWM product has been evaluated and authorized for that marking, rather than being assumed from the AWM Style alone.
Does AWG tell me the finished wire diameter?
No. AWG identifies conductor gauge. Insulation construction and manufacturer dimensions also affect finished wire outside diameter.
Is there a universal AWM wire ampacity chart?
An AWM Style or AWG marking alone does not provide enough information to establish one universal application ampacity. Thermal environment, bundling, terminals, connectors and end-product requirements also matter.
Is surface printing enough to verify UL certification?
Not by itself. Surface printing is useful for identification, while package, reel or tag information and current certification records are used for controlled verification.
Need AWM Wire Reviewed for an OEM Wiring Project?
Send the required AWM Style or wire specification, conductor size, ratings, color, terminal or connector details, drawing, BOM and quantity. WireLoomTech can review the wire requirement together with your internal-wiring or wire-harness project.