By TEBAOFLEX Jyen. Originally published on April 30, 2026.
Insulation temperature is not the complete wire rating
Mica/glass and ceramic-fiber insulation systems can serve high-temperature applications, but their material heat resistance does not automatically establish the voltage and continuous temperature rating of a finished wire. Conductor alloy, braid treatment, atmosphere, support and terminations all matter.
The labels Type MG and CERAFIL CN8 in a purchasing enquiry must be tied to an exact datasheet and qualification. This article does not certify a particular construction for 450 °C or 1000 °C service.
Specify the actual conductor alloy
Nickel-coated or nickel-clad copper and solid nickel conductors differ in resistance, mechanical behavior and oxidation response. A coating percentage alone does not prove a finished-wire operating temperature or service life.
Special Metals distinguishes Nickel 200 from lower-carbon Nickel 201: reduced carbon is important in avoiding intergranular carbon embrittlement at elevated temperature above approximately 315 °C. Consequently, a blanket recommendation for Nickel 200 throughout an 800–1000 °C furnace is not justified. Obtain alloy-specific guidance and cable qualification for the atmosphere and duty.
Use a hot-resistance curve, not a room-temperature shortcut
For a simple DC lead, voltage drop is current times loop resistance. Where the route crosses several thermal zones, calculate each section using its resistance at that section’s operating temperature, then add the drops.
Illustrative arithmetic only: an assumed 0.020 Ω/m operating resistance, 20 m total loop and 25 A produce 10 V drop and 250 W of lead heating. Those assumed values are not ratings for any product. The current-carrying capacity and resulting self-heating still require assessment.
A linear temperature coefficient near room temperature should not be extended to 1000 °C without validated material data. Magnetic transitions and alloy behavior can invalidate a constant-coefficient model.
Installation and test requirements
Keep connectors and transitions within their own ratings, provide suitable support and observe permitted bend/handling conditions after heat exposure. Porous mineral braids can require protection from moisture, contamination and mechanical damage.
For vacuum service, assess the complete construction, binders, cleanliness and feedthroughs. A generic PEEK or polyimide name does not prove suitability for a specified ultra-high vacuum or radiation dose.
Request traceable material identification, applicable voltage tests, hot resistance data and thermal-aging/handling evidence for the supplied design. No measured production results or universal gauge-upsize rule is asserted here.
Primary references and specification evidence
The references explain the cited technology or manufacturer example. They are not TEBAOFLEX product approvals or evidence that a supplied batch has passed the tests. Request the exact product drawing, specification edition, acceptance criteria and traceable records.
Discuss your application
Discuss the duty, installation and required documentary evidence with TEBAOFLEX. WhatsApp: +86 185 9591 3361. Product suitability and test obligations must be confirmed for the specific order.