Which conductor?
The size and strand construction are part of the specification.
A fine-stranded lead and a larger conductor need their own dimensional and termination checks.UL AWM specification guide
UL 3512 Silicone Wire Specification
200°C (392°F) · 600 V
AC in the historical specification.
UL 3512 has a wider conductor range than the historical UL 3135 specification, with insulation thickness requirements that change by conductor size. Its broader conductor scope, size-dependent insulation requirements and construction options give it a distinct role in equipment wiring.
- Temperature reference
- 200°C (392°F)
- Voltage reference
- 600 V AC
- Selection focus
- Size & construction
- Conductor
- Silicone insulation
THE ROLE OF THIS STYLE
Why specify UL 3512 silicone wire?
A specification must describe the wire being built, not just its voltage and temperature. Those two values alone do not tell a buyer which conductor, insulation dimensions or internal layers to expect.
UL 3512 provides a defined construction route across a wider range of conductor sizes than the historical UL 3135 definition. The comparison below covers conductor size, insulation thickness and optional layers.
THE DESIGN QUESTIONWHY IT MATTERS HERE
Which insulation wall?
Start with the selected conductor size, then its applicable wall requirement.
Do not carry the dimensions of a small wire across to a larger version.Which actual build?
Identify any internal layers, as well as the visible silicone insulation.
Two red wires can look alike but be built differently.Use UL 3512 when the equipment specification calls for this style. Confirm the current recognised construction of the actual wire.
SAME RATING DOES NOT MEAN SAME WIRE
UL 3512 vs. UL 3135
Both use silicone insulation. The important distinction is in the permitted conductor scope and construction rules, not a visibly different base material.
Comparison of UL’s historical style definitions. On a small screen, swipe across the table.
| What matters? | UL 3512 THIS STYLE | UL 3135 ↗ |
|---|---|---|
| Rating reference | 200°C (392°F) · 600 V AC | 200°C (392°F) · 600 V AC |
| Insulation material | Extruded silicone rubber | Extruded silicone rubber |
| Conductor scope | 0.3–250 mm² | 26–12 AWG |
| Insulation-wall rule | Minimums vary by conductor-size band | One set of minimums for the stated range |
| Additional layers | Optional separator; optional two-layer insulation with intermediate glass braid | These options are not specified on the legacy style page |
| Tinned strands | A minimum individual-strand diameter is specified | No separate strand-diameter condition stated on the legacy style page |
Insulation wall and substitution
The smallest UL 3512 size band shares the historical UL 3135 minimum-wall values. The distinction becomes clearer across the full construction range. Compare the chosen wire, not the apparent thickness of two drawings.
Sources: UL 3512, UL 3135. These legacy pages are no longer updated. Current product-specific requirements and recognition take precedence.
FROM CONDUCTOR TO FINISHED WIRE
UL 3512 wire size and fit
A change in conductor size can affect both the insulation requirement and the space needed for the finished wire. These are three separate checks.
- CONDUCTOR
Conductor
State the nominal size, conductor finish and stranding. Include the load and termination method so the selected construction can be reviewed.
Define: AWG or mm² + stranding
- INSULATION
Insulation requirement
Use the requirements for that wire size and version. Confirm whether the supplied build includes a separator or internal reinforcement.
Confirm: wall + layer arrangement
- INSTALLATION
Finished dimensions
Use the agreed drawing for terminal entries, sleeves and routing. A nominal conductor area is not the outside diameter of the finished wire.
Check: diameter + terminal fit
Current capacity and bend radius depend on the product and installation, not the UL AWM number alone.
MATERIAL AND STRUCTURE
UL 3512 internal construction
The main cross-section shows a base construction. Optional layers are not present in every UL 3512 wire and must not be assumed from its appearance.
Conductor construction
Conductor finish, strand count and individual-strand diameter describe different aspects of the wire. Specify them together when the connection requires a particular build.
What to verify
Conductor details: material, finish, strand count and individual strand diameter.
Silicone insulation
The insulation surrounds the conductor. Its wall and the finished wire diameter belong to the selected size and construction.
What to verify
Request the actual dimensional drawing. Do not use this representative cross-section to estimate wall thickness or stripping dimensions.
Optional internal layers
A separator or a two-layer construction must be identified explicitly when present. An intermediate glass braid is different from an exposed outer braid.
What to verify
Ask for the complete layer arrangement and preparation instructions. Glass-fibre reinforcement is not a metallic EMC screen.
PUT THE STYLE IN CONTEXT
Typical use of UL 3512 wire
The historical use is appliance wiring within a complete enclosure. Equipment approval and the conditions at the actual connection still matter.
A RELEVANT CONNECTION TO REVIEW
Heat-exposed leads inside equipment
Start with the style on the drawing, then describe the conditions between the component and its terminal.
- Temperature at the wire and both terminations.
- Working voltage, circuit load and installation space.
- Required wire size, routing and mechanical protection.
CHECK BEYOND THE STYLE NUMBER
- Current capacity
- A larger conductor range is not a universal current rating. Installation, thermal conditions and terminations need assessment.
- Movement and exposure
- Do not infer drag-chain life, torsion, outdoor suitability or fluid resistance from the silicone material or style alone.
- Flame classification
- Horizontal flame is the historical style reference. A VW-1 claim needs evidence for the particular wire.
BEFORE SELECTING A SUBSTITUTE
UL 3512 questions
Can I replace UL 3135 with UL 3512 because both say 200°C (392°F) and 600 V?
Not on those ratings alone. Compare the actual size, conductor construction, dimensions, recognition and installation. Keep the specified style unless the equipment’s approval process accepts the change.
Does every UL 3512 wire have a glass braid?
No. The intermediate glass braid is a construction option, not a universal layer. Confirm the supplied version before choosing stripping tools or making assumptions about reinforcement.
Does a softer wire prove a compliant fine-stranded construction?
No. How a wire feels does not show its conductor plating, strand size or UL recognition. Ask us for the construction details and the UL record.
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UL 3512
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General product range; not a UL 3512 product listing.
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