Heat at the connection
A silicone-insulated construction with a defined temperature rating.
The temperature at the wire matters, not just the machine’s set point.UL AWM specification guide
UL 3135 Silicone Wire Specification
Heat-resistant insulation.
For wiring inside equipment.
Silicone-insulated single-core wire for heat-exposed connections inside equipment. The historical UL 3135 specification describes silicone-insulated single-conductor wire rated 200°C (392°F) and 600 V AC for enclosed appliance wiring.
- Temperature reference
- 200°C (392°F)
- Voltage reference
- 600 V AC
- Wiring role
- Enclosed internal wiring
- Conductor
- Silicone insulation
WHY THE STYLE EXISTS
Why specify UL 3135,
not just “silicone wire”?
“Silicone” names an insulation material. It does not, by itself, tell an equipment designer or supplier which electrical, thermal and construction requirements to work to.
It defines the conductor range, insulation requirements, ratings and intended use for the internal wire.
THE WIRING NEEDWHAT THE STYLE DEFINES
Electrical insulation
A voltage rating together with minimum insulation-wall requirements.
The insulation material alone does not set a wire’s voltage rating.A repeatable specification
Conductor scope, insulation construction, flame-test classification and intended use.
Engineering and purchasing can refer to the same set of requirements.A style number identifies a requirement. It is not a wire size, a supplier’s part number or approval of the complete appliance.
MATERIAL & STRUCTURE
UL 3135 construction
The simple cross-section has two different jobs: carry current through the conductor, and electrically insulate it with silicone.
Silicone insulation
Silicone rubber is used in heat-resistant equipment wiring. Here, it is extruded around the conductor as an insulating layer.
What that means
The material and wall construction work together. “Silicone” alone does not promise abrasion resistance or continuous-flex life.
One conductor
An individual insulated lead can be routed to its own connection. The style allows solid or stranded construction; the illustration shows strands.
What that means
Stranding affects handling and termination. Confirm the actual strand construction and conductor finish for the selected wire.
No common outer jacket
This is an insulated single wire, not several insulated cores inside a protective cable sheath.
What that means
Installation protection comes from the equipment design. This is an individual insulated conductor, rather than several cores within a common cable jacket.
THE DIFFERENCE IS IN THE REQUIREMENTS
UL 3135 vs. UL 3132 and UL 3512
UL 3132, UL 3135 and UL 3512 can look alike. Neither the colour nor the apparent thickness of a cut end identifies the style reliably.
Compare the historical style definitions below. On a small screen, swipe across the table.
| What changes? | UL 3132 ↗ | UL 3135 THIS STYLE | UL 3512 ↗ |
|---|---|---|---|
| Rating reference | 150°C (302°F) · 300 V AC | 200°C (392°F) · 600 V AC | 200°C (392°F) · 600 V AC |
| Basic insulation | Extruded silicone rubber | Extruded silicone rubber | Extruded silicone rubber |
| Conductor scope | 30 AWG–4/0 AWG | 26–12 AWG | 0.3–250 mm²; additional strand restrictions |
| Insulation-wall rule | Lower minimum wall requirement than UL 3135 | One minimum-wall requirement across its conductor range | Minimum wall changes with conductor-size bands |
| Construction detail | An optional covering is described | Single conductor with an extruded insulating layer | Optional separator; optional two-layer insulation with an intermediate glass braid |
Why not replace UL 3135 with UL 3512?
The headline temperature and voltage match, but the permitted conductor and insulation rules do not. Some constructions may look similar; retain the specified style and verify the exact wire before making a substitution.
Comparison sources: UL 3132, UL 3135, UL 3512. These legacy pages are historical references, not current manufacturer authorisations.
WHERE IT FITS
Typical use of UL 3135 wire
The historical UL 3135 use is wiring totally enclosed within appliances. Suitability still depends on the actual wire and the equipment design.
WHEN TO CONSIDER IT
A heat-exposed lead inside equipment
Consider this style when the equipment specification calls for a silicone-insulated, individual internal connection with the required thermal and electrical ratings.
- Locate the wire inside the equipment enclosure.
- Check heat at the lead, termination and nearby components.
- Match the wire to the connection and the equipment’s approval requirements.
Use and installation limits
- Any installation
- Not a general-purpose building wire or an automatically suitable external power cord.
- Unlimited movement
- A heat rating says nothing about drag-chain, torsion or repeated-bend performance.
- Every fire classification
- Horizontal flame is the legacy style reference. Do not infer VW-1, fire survival or other tests from the style number alone.
READ THE REQUIREMENT CORRECTLY
UL 3135 questions
Does 200°C (392°F) mean it can touch any 200°C (392°F) heater?
No. Check the temperature at the wire and its termination, the routing, contact conditions and the selected product’s installation instructions. A heater set point is not a complete cable operating condition.
How does UL 3135 differ from UL 3132?
In the historical definitions, UL 3135 is rated 200°C (392°F) and 600 V AC; UL 3132 is rated 150°C (302°F) and 300 V AC. Their minimum insulation-thickness requirements also differ.
Does “UL 3135” on a product page prove recognition?
No. Check the manufacturer’s current UL record, the specific wire construction and the applicable markings. A component recognition also does not approve the complete piece of equipment.
Related products
Related single-core wire
Browse single-core products by construction and size.
UL 3135
Browse single-core silicone wires ↗Single-core silicone wire
Browse the single-core product range
General product range; not a UL 3135 product listing.
Does your drawing specify UL 3135?
We offer free samples.