TC-K-PTFE/FEP
PTFE and FEP Insulated High-Temperature Thermocouple Extension Cable
Insulation that survives the route when a PVC sheath would already have failed.
On a furnace, a kiln car or an extrusion die, the limiting component is rarely the thermocouple alloy and almost always the insulation. PTFE holds its electrical and mechanical properties continuously to 260 °C, FEP to about 200 °C with a more flexible finish, and both resist the oils, solvents and flux fumes that destroy a PVC sheath long before its temperature rating is reached.
Voltcore supplies these grades with Type K conductors in KX or KCA alloy, screened with a tinned copper or nickel-plated braid so that the millivolt signal survives the electrical noise around heating elements and contactors. The cable is rated for the route, not for the process: it needs to withstand the temperature along its length, which is why installers keep the last 300 mm away from the hot zone and use a mineral-insulated lead or the sensor's own extension where the heat is extreme.
Specification
| Item | Value |
|---|---|
| Thermocouple type | Type K; Type J, T, E and N available on request |
| Cable grade | KX extension or KCA compensating, Class 1 or Class 2 |
| Insulation | PTFE (continuous 260 °C) or FEP (continuous 200 °C) |
| Temperature range | PTFE −200 °C to +260 °C; FEP −200 °C to +200 °C |
| Conductor | Stranded alloy conductor, KX NiCr / NiSi or KCA Cu / CuNi |
| Cross-section range | 0.5 – 2.5 mm² |
| Screen | Tinned copper braid, or nickel-plated copper braid for the higher temperature routes |
| Sheath | PTFE or FEP, colour coded to IEC 60584-3 |
| Rated voltage | 300/500 V |
| Dielectric strength | 5 kV rms minimum at the rated temperature range |
| Flame behaviour | PTFE and FEP do not support combustion; low smoke on decomposition |
| Minimum bending radius | 10 × cable overall diameter at ambient |
Layer-by-layer construction
Listed from the conductor outward. Read this alongside the specification table — the two together tell you whether the cable will survive its installation method.
- 1. ConductorPositive leg nickel-chromium, negative leg nickel-silicon for KX; copper and copper-nickel for KCA
- 2. InsulationPTFE tape or extruded FEP applied per conductor at 0.35–0.50 mm wall, rated 260 °C or 200 °C
- 3. Pair twistingThe two conductors twisted at a 30–50 mm lay length, held by a high-temperature binder
- 4. BinderPTFE or glass fibre binder tape rated to the insulation temperature
- 5. ScreenTinned copper braid, or nickel-plated copper braid where the route approaches the upper temperature limit
- 6. SheathPTFE or FEP extruded sheath, colour coded to IEC 60584-3
Reference dimensions and weights
| Pairs × cross-section (mm²) | Conductor structure (No./mm) | Insulation wall thickness (mm) | Approx. overall diameter (mm) | Approx. weight (kg/km) | KX loop resistance (Ω/km) | Continuous temperature rating (°C) |
|---|---|---|---|---|---|---|
| 1×2×0.5 | 7/0.30 | 0.35 | 3.2 | 28 | 1 980 | 260 (PTFE) / 200 (FEP) |
| 1×2×0.75 | 7/0.37 | 0.35 | 3.6 | 38 | 1 320 | 260 (PTFE) / 200 (FEP) |
| 1×2×1.0 | 7/0.43 | 0.40 | 4.2 | 52 | 990 | 260 (PTFE) / 200 (FEP) |
| 1×2×1.5 | 7/0.52 | 0.45 | 4.8 | 72 | 660 | 260 (PTFE) / 200 (FEP) |
| 1×2×2.5 | 7/0.68 | 0.50 | 5.8 | 112 | 396 | 260 (PTFE) / 200 (FEP) |
Reference figures for preliminary sizing and drum planning. Overall diameter and weight vary with strand construction and sheath thickness tolerance; certified drawings are issued with each quotation.
Engineering characteristics
- PTFE insulation rated continuously to 260 °C and FEP to 200 °C, both usable down to −200 °C
- Insulation and sheath resist oils, solvents and most process chemicals that attack PVC
- Nickel-plated copper braid option holds the screen together at temperatures where tin would soften
- Dielectric strength of at least 5 kV rms across the rated temperature range
- KX or KCA alloy conductors, Class 1 ±1.5 °C or Class 2 ±2.5 °C tolerance
- PTFE and FEP do not support combustion, which suits enclosed oven and kiln installations
- Type K as standard; Type J, T, E and N conductors supplied on request
Typical applications
- Furnace, kiln and oven thermocouple runs where the cable passes through heated zones
- Plastics extrusion and injection moulding machine barrel and die temperature circuits
- Heat treatment lines, annealing furnaces and tempering baths
- Engine test cells, exhaust gas and turbocharger temperature measurement
- Chemical and petrochemical plant where heat and solvent exposure coincide
Ordering options
- PTFE insulation to 260 °C or FEP to 200 °C
- Tinned copper braid or nickel-plated copper braid screen
- KX extension or KCA compensating alloy conductors
- Type J, T, E and N conductors for other thermocouple types
- Glass fibre braid and high-temperature varnish finish for abrasion resistance
Standards manufactured to
- IEC 60584-3 (extension and compensating cable, tolerances and colour coding)
- IEC 60228 (conductor construction)
- UL 758 (appliance wiring material practice where applicable)
- IEC 60332-1-2 (flame propagation)
- RoHS and REACH compliant compounds
Manufactured to other standards on request. Send the standard number with your RFQ and we will quote against it rather than against a near-equivalent.
Price and availability for PTFE / FEP Insulated High-Temperature Extension Cable
Include cross-section, core count, voltage grade, route length and installation method — those five determine price more than anything else on the page.
- Engineer-reviewed before pricing
- Reference drawings issued with the quotation
- Free sample up to free sample up to 5 m
PTFE / FEP Insulated High-Temperature Extension Cable — frequently asked questions
Can the cable be rated for the process temperature?
It should be rated for the route, not the process. The cable only has to survive the temperature it is exposed to along its length, which is normally far below the temperature at the sensor tip. Keep the last 300 mm clear of the hot zone or use the sensor's own mineral-insulated lead.
PTFE or FEP — how do I choose?
PTFE for the higher continuous rating of 260 °C and the widest chemical resistance; FEP for 200 °C with better flexibility and easier stripping. PTFE is stiffer and will cold-flow under a tight clamp, so use the right gland for it.
Will the screen survive at 250 °C?
Specify the nickel-plated copper braid at that temperature. A standard tinned braid is fine to about 150 °C, above which the tin coating softens and the braid can lose contact with the termination hardware.
Is the cable flexible at high temperature?
FEP stays reasonably flexible across its range. PTFE stiffens and is prone to cold flow under pressure, so support it on a tray or cleat rather than clamping it tightly, and allow a generous bend at the termination.
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