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High Temperature Cables 8 min readApril 19, 2026

High-Temperature Wire Guide: Silicone vs PTFE vs Mica — Which to Choose?

High-temperature wire is not a single category — it spans four fundamentally different insulation technologies with very different capabilities. This guide compares silicone rubber, PTFE, FEP, and mica insulation so you can select the right construction for your application.

PropertySilicone RubberPTFE (Polytetrafluoroethylene)FEP (Fluorinated Ethylene Propylene)Mica/Fiberglass
Temperature Range-60°C to +200°C-65°C to +260°C-65°C to +200°CUp to 650°C–1000°C
Voltage Class300V–1140V250V–600V300V–600V450V–600V
FlexibilityExcellentGoodExcellentLimited
Chemical ResistanceGoodOutstandingExcellentGood
Relative CostModerateHighModerate-HighHigh

Silicone Rubber

-60°C to +200°C · 300V–1140V · Flexibility: Excellent

Strengths

  • Outstanding flexibility at extreme temperatures (both hot and cold)
  • Excellent weather and UV resistance
  • Good dielectric properties
  • Soft, pliable, and easy to work with
  • Biocompatible grades available

Best For

  • Appliance wiring
  • Industrial furnace connections
  • Marine applications
  • Robotics and automation
  • Medical device wiring

PTFE (Polytetrafluoroethylene)

-65°C to +260°C · 250V–600V · Flexibility: Good

Strengths

  • Widest chemical resistance of any common insulation — resistant to nearly all acids, bases, solvents
  • Very low coefficient of friction — easy to thread through conduit
  • Excellent dielectric properties
  • Non-stick surface resists contamination
  • FDA compliant grades for food processing

Best For

  • Chemical processing plants
  • Laboratory instrumentation
  • Food and pharmaceutical equipment
  • High-vacuum equipment
  • Aerospace wiring

FEP (Fluorinated Ethylene Propylene)

-65°C to +200°C · 300V–600V · Flexibility: Excellent

Strengths

  • Better flexibility than PTFE while retaining most chemical resistance
  • Available in plenum-rated constructions (substitutes for PTFE in some plenum applications)
  • Smooth, low-friction surface
  • Transparent available — useful for visual inspection

Best For

  • Data center and plenum wiring
  • Chemical instrumentation
  • Telecommunications
  • Clean room environments

Mica/Fiberglass

Up to 650°C–1000°C · 450V–600V · Flexibility: Limited

Strengths

  • Highest temperature rating of any commercially available insulation
  • Mica maintains circuit integrity under direct flame (fire resistant)
  • Pure nickel mica variants rated to 1000°C
  • Used where no polymer insulation can survive

Best For

  • Steel and foundry furnace wiring
  • Nuclear facilities
  • Emergency circuit survival cables
  • High-temperature process instruments
  • Thermocouple extension above 150°C

Not Sure Which High-Temp Wire You Need?

Our engineers can recommend the right insulation type based on your temperature, chemical, and mechanical requirements. Free samples available for all product lines.

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