What heat reaches the lead?
A silicone-insulated construction with a 150°C (302°F) style reference.
Check the wire and termination temperatures, not only the equipment’s operating temperature.UL AWM specification guide
UL 3132 Silicone Wire Specification
Heat-resistant insulation.
A 300 V internal connection.
UL 3132 brings silicone insulation to individual leads inside enclosed equipment. The historical UL 3132 specification gives 150°C (302°F) and 300 V AC for enclosed internal wiring, with defined silicone-insulation requirements.
- Temperature reference
- 150°C (302°F)
- Voltage reference
- 300 V AC
- Wiring role
- Enclosed internal wiring
- Conductor
- Silicone insulation
THE ROLE OF THIS STYLE
Why specify UL 3132 silicone wire?
A connection can need heat-resistant insulation without calling for the rating and construction of a 600 V wire. Electrical duty and heat exposure are separate design requirements.
The historical UL 3132 and UL 3135 specifications differ in temperature, voltage and minimum insulation thickness.
THE DESIGN QUESTIONHOW UL 3132 FITS
What electrical rating is required?
A 300 V AC reference with specified insulation requirements.
Do not select a voltage rating simply because two wires use the same material.Where is the wire installed?
An individual connection within enclosed equipment.
Its internal-wiring role is different from an exposed supply cord or building wiring.The style sets the reference. The actual wire size, dimensions, recognition and installation still belong to the selected product.
INSIDE A UL 3132 CONSTRUCTION
UL 3132 construction
The conductor is surrounded by silicone insulation. An additional covering is optional in the historical definition.
The conductor
Carries the electrical connection. A solid conductor and a stranded conductor are different constructions; the image shows a stranded example.
Specify separately
Wire size, conductor finish and stranding determine what goes into the terminal. The same AWG can have different strand arrangements.
The silicone wall
Provides the insulating layer around the conductor. Silicone is used in heat-resistant wiring; the complete construction determines its ratings.
Specify separately
Wall thickness and finished diameter affect installation space and termination fit. They are not interchangeable with AWG.
An optional covering
The legacy style allows an additional covering. The base cross-section above does not include one.
Specify separately
If a drawing requires a braid or other covering, identify it explicitly. UL 3132 wire does not always include one.
UNDERSTAND THE THINNER WALL
UL 3132 insulation wall thickness
Compared with UL 3135, the historical UL 3132 definition has a lower minimum insulation-wall requirement.
For otherwise comparable conductors and constructions, a thinner wall can reduce the finished diameter. Finished diameter also depends on the conductor and any additional covering.
Compare the construction rules ↓It can change the outside dimension.
Check the actual wire diameter against terminal entries, sleeves and routing space. Use the product drawing, not the apparent size of a schematic.
It does not tell you the copper area.
Choose the conductor for the circuit and termination. Insulation wall thickness alone does not determine current capacity.
It does not tell you the flex life.
Handling also depends on the conductor stranding and insulation compound. Continuous bending needs its own construction and test.
TWO DIFFERENT REASONS TO COMPARE
UL 3132 vs. UL 3135 and UL 3122
UL 3135 changes the thermal, electrical and insulation requirements. UL 3122 keeps a 300 V AC reference but specifies a different temperature and a lacquered braid.
Historical style definitions, not a list of interchangeable products. On a small screen, swipe across the table.
| What matters? | UL 3132 THIS STYLE | UL 3135 ↗ | UL 3122 ↗ |
|---|---|---|---|
| Rating reference | 150°C (302°F) · 300 V AC | 200°C (392°F) · 600 V AC | 200°C (392°F) · 300 V AC |
| Basic insulation | Extruded silicone rubber | Extruded silicone rubber | Extruded silicone rubber |
| Conductor scope | 30 AWG–4/0 AWG | 26–12 AWG | 26–16 AWG |
| Minimum-wall relationship | Lower minimum than UL 3135 | Higher minimum than UL 3132 | Same legacy minimum as UL 3132, with an added braid |
| Outer covering | Optional covering | No separate covering specified on the legacy style page | Lacquered braid specified |
Neither change is just a new label.
A higher rating or an added braid changes what needs to be checked. Keep the style required by the drawing, and compare the actual wire before approving a substitute.
Sources: UL 3132, UL 3135, UL 3122. UL’s legacy pages are no longer maintained. Confirm current, product-specific requirements.
PUT THE STYLE IN CONTEXT
Typical use of UL 3132 wire
The historical use is internal wiring where totally enclosed. Intended use in the historical specification: internal wiring within a complete enclosure.
A RELEVANT CONNECTION TO REVIEW
An individual lead in a heat-exposed enclosure
Review UL 3132 when the design calls for this silicone-wire style and the connection’s electrical and thermal requirements fit the selected wire.
- Identify heat around the routing and terminal.
- Match the conductor and insulation diameter to the connection.
- Check mechanical protection, assembly and product documentation.
CHECK BEYOND THE STYLE NUMBER
- Installation exposure
- Outdoor use, fluids, abrasion or direct contact with hot components need separate assessment.
- Motion and cable role
- Do not infer drag-chain life, torsion capability or external-cord suitability from silicone insulation.
- Flame-test claims
- Horizontal flame is the legacy style reference. VW-1 and other classifications need evidence for the actual product.
WHAT THE NUMBER DOES NOT TELL YOU
UL 3132 questions
Is every UL 3132 wire smaller than every UL 3135 wire?
No. Finished diameter also depends on conductor size, stranding, the actual insulation wall and any covering. Compare the same conductor size and the supplier’s dimensional drawing.
Why can the test voltage be higher than the rated voltage?
A test applies a specified voltage under defined test conditions and for a specified duration. It is not the permitted continuous operating voltage. Keep the product’s rating and its test specification separate.
Does the full style range mean every size is available?
No. A style’s permitted conductor range is different from a manufacturer’s recognised constructions and available product range. Select an actual product and confirm its current documentation.
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