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Product

High-temperature wireUL AWM Style 3257+250 °C Silicone2500 V DC / 15 kV Pulse

UL AWM 3257 High-Voltage Silicone Ignition WireUL 758 Style 3257 +250 °C high-temperature silicone ignition wire with Ni-Cu conductor

UL AWM Style 3257 high-temperature silicone ignition and lead wire engineered with nickel-plated or silver-plated copper conductors and a +250 °C thermal-grade phenyl/vinyl silicone rubber wall (≥ 1.14 mm) for 2500 V DC continuous and 15–25 kV pulse ignition.

Flame-retardant
Approved
Ozone, UV & moisture
Order designation
UL 3257 18 AWG
Outer Ø ≈
3.60 mm
Wall thickness
1.14 mm
Total weight ≈
20.0 kg/km
Min. bend R (fixed)
22 mm
All sizes (8)
Request a quoteDatasheetWhatsApp
Engineering reply in 2 business hoursCut-to-length export drumsEN 10204 3.1 certificate per drum
Rated voltage
2500 V DC
UL 3257 · 15–25 kV spark pulse
Temperature
-60…+250 °C
UL 3257 +250 °C continuous
Conductor
Ni-Cu / Ag-Cu
Nickel- or silver-plated copper
Wall thickness
≥ 1.14 mm
45 mil min. extruded VMQ wall
Spark test
15 kV AC rms
100 % in-line dielectric check
Size range
24 to 10 AWG
0.20 to 5.26 mm² single-core

Typical values for this cable type, based on UL 758 AWM Style 3257 — confirmed in the datasheet and quotation for your order.

Application fit

Is UL AWM 3257 right for your machine?

Choose UL AWM 3257 when unbraided silicone ignition or HV lead wire must operate continuously at +250 °C — 50 °C to 100 °C above the thermal ceiling of standard UL 3239.

Furnace, kiln & high-temp zone

Suitable

Formulated with +250 °C thermal-stabilised silicone elastomer and nickel-plated copper for high-heat gas igniters and pyrolysis ovens.

Switchgear & control cabinet wiring

Suitable

Unbraided smooth silicone outer wall strips cleanly without glass-fibre dust for high-voltage electronics and compact burner boxes.

Fixed installation

Suitable

Suitable for internal appliance wiring, commercial cooking equipment, and high-temperature HV modules.

Motorised monospiral reel

Not suitable

Single-core unbraided silicone appliance wire is for fixed internal wiring only.

Use NSHTÖU for drum reeling
Typical machinesSelf-Cleaning & Pyrolysis OvensHigh-Temp Gas Burner IgnitersSemiconductor Diffusion HeatersIndustrial Drying & CuringHigh-Voltage Power Modules

Construction

Layer by layer

UL 758 Style 3257 single-core construction: stranded nickel-plated copper conductor (ASTM B355) and extruded +250 °C silicone rubber insulation (≥ 1.14 mm wall).

1234
Schematic, not to scale — generated from the layer data
#LayerMaterial & reference
1Nickel-plated copper conductorStranded 27 % nickel-plated annealed copper (ASTM B355) or silver-plated copper (24–10 AWG)Prevents copper oxidation and intermetallic degradation at +250 °C continuous
2Conductor barrier interfaceClean-stripping separator interface over stranded Ni-Cu coreAllows rapid automated stripping for igniter electrode crimping
3+250 °C silicone rubber wallExtruded heat-stabilised silicone rubber (45 mil / 1.14 mm to 2.0 mm wall)Retains dielectric strength and elongation after 60-day UL thermal ageing at +260 °C
4Corona-resistant outer skinHomogeneous arc- and ozone-resistant silicone surfacePasses UL Horizontal / VW-1 flame test and 15 kV in-line spark test

UL 3257 Standard (1.14 mm wall)

2500 V DC continuous / 15 kV pulse ignition wire with 45 mil +250 °C silicone wall

UL 3257 Heavy Wall (1.8–2.2 mm)

Enhanced 20–25 kV pulse ignition lead for high-energy spark electrodes at +250 °C

Technical data

Ratings & operating limits

Typical values: Typical values for this cable type, based on UL 758 AWM Style 3257. Values for your order are confirmed in the datasheet and quotation.

Electrical

UL rated voltage
2500 V DC continuous
High-voltage ignition pulse
Up to 15 kV – 25 kV peak spark pulse
Dielectric withstand test
6000 V AC rms (dielectric) · 15 kV spark
Volume resistivity
≥ 10¹⁴ Ω·cm at +20 °C

Thermal

UL continuous temperature
-60 °C to +250 °C
Short-term thermal peak
+280 °C intermittent excursion
Low-temperature flexibility
-60 °C cold-bend compliant

Mechanical

Conductor gauge range
24 AWG to 10 AWG (0.20 to 5.26 mm²)
Minimum insulation thickness
45 mil (1.14 mm) per UL 758 Style 3257
Min. bending radius
5 × overall wire diameter (fixed)

Resistance

Flame test
UL Horizontal & UL VW-1 flame retardant
Ozone & corona resistance
Resists ozone, corona, and moisture
Halogen-free compound
Zero halogens per IEC 60754-1/2

Reference standards

Appliance wire standard
UL 758 AWM Style 3257
Conductor standard
ASTM B355 Class 27 / Class 10 Ni-Cu
RoHS & REACH
RoHS 3 & REACH compliant

Identification

Standard colours
Red-brown, white, black, orange, yellow
Surface legend
TEBAOFLEX AWM STYLE 3257 250C 2500VDC VW-1
Customs tariff (HS)
8544.49

Sizes

8 standard configurations (UL AWM 3257)

Engineering dimensions, conductor stranding, mass and electrical ratings for UL AWM 3257 per UL 758 AWM Style 3257.

Dimensions & weights
Order designationCross-section / sizeConductor buildWall ≈
mm		Outer Ø ≈
mm		Metal
kg/km		Weight ≈
kg/km		Min. bend R
fixed mm		Enquiry
Standard UL AWM 3257 configurations
UL 3257 24 AWG24 AWG (0.20 mm²)7×0.20 mm Ni-Cu1.142.902.011.017
UL 3257 22 AWG22 AWG (0.35 mm²)7×0.25 mm Ni-Cu1.143.103.413.019
UL 3257 20 AWG20 AWG (0.52 mm²)19×0.19 mm Ni-Cu1.143.305.216.020
UL 3257 18 AWG18 AWG (0.82 mm²)19×0.235 mm Ni-Cu1.143.608.220.022
UL 3257 16 AWG16 AWG (1.31 mm²)19×0.30 mm Ni-Cu1.143.9013.026.023
UL 3257 14 AWG14 AWG (2.08 mm²)19×0.37 mm Ni-Cu1.144.3020.535.026
UL 3257 12 AWG12 AWG (3.31 mm²)19×0.47 mm Ni-Cu1.144.8032.549.029
UL 3257 10 AWG10 AWG (5.26 mm²)37×0.43 mm Ni-Cu1.145.4051.571.032
  • Typical values for this cable type; dimensions and weights for your order are confirmed in the quotation.
  • Outer diameters and weights are nominal engineering values for UL AWM 3257 subject to standard manufacturing tolerances per UL 758 AWM Style 3257.

Quality & approvals

Testing & inspection

Routine tests on every production length, sample and type tests per batch — documented on an EN 10204 3.1 inspection certificate.

  1. ConductorClass 5 stranding
  2. Spark test100 % in-line
  3. Lay-upCores, earth, fillers
  4. SheathingInner, braid / screen, outer
  5. Electrical testsAC voltage, resistance
  6. DimensionsOD, wall thickness
  7. Inspection documents & dispatchDrum & dispatch
Testing & inspectionTest value / referenceFrequency
Routine tests
Dielectric spark / high-voltage withstand test100 % in-line spark and AC/DC dielectric withstand per UL 758 AWM Style 3257Every manufactured length
Conductor DC resistance & continuity checkWithin maximum 20 °C resistance limit specified for UL AWM 3257Every spool or drum length
Sample tests
Thermal ageing & dimensional verificationWall thickness, concentricity and post-ageing elongation per UL 758 AWM Style 3257Per production batch
Flame, outgassing or high-temperature enduranceQualified to UL 758 AWM Style 3257 thermal and environmental performance criteriaType qualification

Inspection certificate

Issued with every drum, listing the routine test results for that length.

Product approvals

UL 758 AWM Style 3257CE (2014/35/EU) & RoHS 3 (2015/863/EU) CompliantREACH SVHC & Halogen/Asbestos Compliance Verified

Company certificates

ISO 9001ISO 14001ISO 45001VDE marks approvalUL / cULCE · LVD / EMC

Marking & supply

Ordering & delivery

Sheath marking

TEBAOFLEX E-FILE AWM STYLE 3257 18 AWG 250C 2500VDC VW-1
Delivery form
Precision spools, coils or export wooden drums
Standard lengths
50 m · 100 m · 500 m · 1000 m (or cut harnesses)
MOQ
100 m (stock sizes) · 300–500 m (custom build)
Lead time
2–4 weeks ex-works
Incoterms
EXW, FOB, CIF, DAP

Technical documents

Downloads

PDFUL AWM 3257 High-Voltage Silicone Ignition Wire – technical datasheet8 sizes · construction, technical data, approvalsXLSXUL AWM 3257 spec data (Excel)All 8 sizes with dimensions and data, for your BOM or quotation
Revision
2026-10-20
Updated
2026-10-20

FAQ

Questions engineers ask first

Not covered here? Send your drawing — an engineer replies within 2 business hours.

How does UL AWM Style 3257 differ from UL AWM Style 3239?
UL Style 3257 is specifically certified for +250 °C continuous operation at 2500 V DC (with high-voltage spark ignition capability up to 15–25 kV) using nickel- or silver-plated copper conductors. UL Style 3239 is rated +150 °C (+200 °C max) with tinned copper conductors across 3 kV to 50 kV DC.
Why does UL 3257 use nickel-plated copper instead of tinned copper?
Tin melts at +231.9 °C, so tinned copper cannot be used at UL 3257's +250 °C continuous temperature rating. A 27 % nickel plating (ASTM B355) or silver plating protects the copper strands against oxidation and intermetallic fusing at +250 °C.
Can UL 3257 be used for piezo and electronic spark ignition in pyrolytic self-cleaning ovens?
Yes. Pyrolytic self-cleaning ovens generate cavity-wall ambient temperatures around +220 °C to +250 °C where 150 °C or 180 °C ignition wires fail prematurely. UL 3257 is the standard unbraided silicone ignition lead for those cavities.
What terminal crimps should be used on UL 3257 at +250 °C?
Use nickel-plated steel or pure nickel crimp terminals (including 2.8 mm / 4.8 mm / 6.3 mm high-temp quick-disconnects or spark plug receptacles) rather than standard tin-plated brass terminals.

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UL AWM 3257 High-Voltage Silicone Ignition Wire

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