Thermocouple Wire & Cable Sensors — Bare Wire · Duplex · Extension Cable

Wire and Cable Sensor Routing

Wire thermocouples are built around insulation, conductor type, exposed or protected junction style, and lead construction for custom routing or harness integration. Dual and duplex versions can place redundant thermocouple circuits into an aerospace or OEM harness where one routed package needs separate control, monitoring, or validation channels.

Thermocouple Wire Product Guide

Thermocouple Grade vs Extension Grade

Thermocouple-grade wire uses the actual thermocouple alloys (e.g., Chromel/Alumel for Type K) and is calibrated to sensing tolerances per ASTM E230. Extension-grade wire uses lower-cost alloys with the same Seebeck coefficient within a limited temperature range (typically 0°C to 200°C) and is only intended for the run from the sensor to the instrument panel. Never use extension-grade wire in the sensing zone — it introduces calibration error outside its rated range. Thermometrics supplies both grades; extension cables are color-coded to match the sensing type per ANSI MC96.1.

Insulation Selection Guide

• Below 260°C: PFA is usually the preferred lead insulation because it is close to PVC in cost while offering better temperature capability and chemical resistance.
• Below 105°C in dry, low-demand locations: PVC can still be used when the lowest material cost is the only driver.
• Wet or chemical environments: PFA/PTFE fluoropolymer insulation is preferred over PVC.
• 260–480°C: fiberglass braid is commonly used.
• 480–1200°C: ceramic fiber braid is required.
• Inside furnace or flame zones: use ceramic fiber only.

Dual and Duplex Cable Builds

Dual and duplex wire sensors are used when one routed cable or harness needs two independent sensing circuits. Aerospace programs may use this approach for qualification fixtures, engine-adjacent test wiring, redundant validation channels, or split monitoring where routing space and documentation control matter as much as the sensing junction.