Thermocouple wire is the most cost-effective means of temperature measurement. It consists of at least one pair of insulated wires that are oriented parallel to each other and secured together with a protective shield and/or jacket. The wire can be one of several calibrations or Types and is available in a solid or stranded core in a wide variety of gauges. Solid core wire is more common, but a stranded construction is available when greater flexibility is needed. Thermocouple grade wire is the highest quality wire that should be used in the hot zone where measurements are taking place. Cleveland Electric Laboratories supplies thermocouple grade wire with special limits of error or better as a standard. Extension wire is used to carry the signal generated from a thermocouple to measurement equipment or elsewhere and the requirements for this wire are more relaxed. The wire used in extension wire are made from the same materials as thermocouple wire. Alternatively, compensating cable can be used. This wire is made from materials from the corresponding Type of thermocouple wire but have similar electrical characteristics to limit their contribution to measurement error.

Insulation is then applied to each wire individually, and then again as a pair. The insulation may be extruded, taped, wrapped, served, braided, or applied using other means depending on insulation material and desired end characteristics. This insulation isolates each wire from the other electrically and may also serve to identify the calibration type as well as identify the polarity of each wire. Some types of high temperature insulation cannot accept color coding and tracer materials are added for identification. Insulation type is highly dependent on the end application with the maximum usage temperature and the atmosphere being the driving factors. Other factors when choosing insulation material are flexibility, abrasion, electromagnetic interference, In addition to the outer insulation, other layers may be added like foils or stainless-steel braiding to provide electrical shielding or abrasion resistance. Cleveland Electric Laboratories maintains a large inventory of many stock wire configurations. Custom combinations are available upon request.

Thermocouple and Extension wire assemblies are available in long, continuous lengths and are custom built to specification. Cold end termination options include stripped, bare ends, industry-standard plugs/jacks, or custom options.

Survey/Profile Thermocouples

Insulated Thermocouple Wire (ITW) is an effective tool to measure the accuracy and stability of Industrial Furnaces—thus the common terminology of Survey or Profile Thermocouples. Material is available in bulk spools or as made-to-order thermocouples or Thermocouple Kits, all in accordance to industry specifications.

Technical Data

Calibration: E, J, K, N & T
Sheath Diameters: 14-30 Gauge
Sheath Materials: Stainless Steel & Inconel
Junction Construction: Twist, Butt Weld with Stainless Steel Overbraid
Termination and Hardware: Plugs, Jacks & Mini Plugs
Certification: Individual or Lot Certification; Special Limits of Error

Extension Lead Assemblies/Harnesses

Manufactured with either Insulated Thermocouple Wire (ITW) or Insulated Extension Wire (IEW), CEL is able to supply application-specific assemblies or harnesses for compatibility to your existing process.

Technical Data

Full Customizations of Products Available Upon Request.

Insulated Thermocouple & Extension Wire

Insulated Thermocouple Wire (ITW) is selected based on necessary calibration, diameter, and insulation material. Our ITW is typically ordered in bulk spools and may be certified in our ISO/IEC 17025 accredited laboratory.

Insulated Extension Wire
Insulated Extension Wire (IEW) is used as a means to transmit a thermocouple signal from the sensor in process to the recording instrumentation without loss or degradation of the thermocouple signal. IEW must be compatible with its corresponding thermocouple.

Technical Data

Calibration: B, C, E, J, K, N, R, S & T
Wire Gauge: 14 – 30 Gauge
Insulating Materials: 200°F – 2400°F. Various Materials Available Upon Request
Certification: Lot Certification; Special Limits of Error

Noble Metal Thermocouple Wire

Provide tighter accuracies than base metal assemblies and are manufactured with superior materials capable of withstanding process temperatures up to 3100°F.

Supplied in Types B, R or S, our Noble Thermocouple Wire is suitable for high-temperature and high-accuracy applications. Standard in-stock wire diameters range from .010” to .032”, all available with ISO/IEC 17025 accredited calibration upon request.


Forging, Blast Furnaces, Steel Production, Tunnel Kilns & High-Temperature Periodic Kiln

Technical Data

Calibration: B, R & S
Wire Gauge: .002 – .45
Termination and Hardware Options

Base Metal Thermocouple Wire

Rugged, durable industrial thermocouple assemblies designed for use in the most severe process environments & temperatures up 2200°F.


Steel Production, Waste Incineration, Heat Treating, Salt Baths & Rotary Kilns

Technical Data

Calibration: E, J, K, N & T
Gauge: 8-20 (Others Available Upon Request)
Hardware: Multiple Mounting
Certification:  Lot Certification; Special Limits of Error

Multi-Pair Thermocouples Wire

From 2 to 36 pair of wire in a common cable, our Multi-Pair Extension Wire is utilized when a single run of instrumentation wiring is desired. This configuration greatly simplifies installation when many wires are routed to a single point. It also occupies less space.

Technical Data

Calibration: B, R & S
Wire Gauge: All Diameters
Insulating Materials: 200°F – 700°F. Polyvinyl Twisted, Twisted Aluminum Mylar/PVC

Magnesium Oxide Cable

Also known as MgO or MIMS Cable, this material is supplied with a metallic outer sheath, typically Inconel or Stainless Steel. High-temperature magnesium-oxide insulation encapsulates the thermo conductors, isolating the conductors from each other as well as the outer sheath. This versatile product is manufactured for flexibility, able to be wrapped around a mandrel twice the diameter of the cable.


Heat Treating, Forging, Annealing, Hardening, Engine Testing and Monitoring, Specialty Metals Processing, Oil & Gas Refining

Technical Data

Calibration: B, E, J, K, N, R, S & T
Sheath Diameter: 0.010” – .75”
Sheath Material: Inconel & Stainless Steel
Certification: Lot Certification; Special Limits of Error

Industrial Thermocouple Additional Services

  • Calibration & Certification Lab

  • Repair & Recalibration

  • Exchange Programs

  • Engineering Services

  • Value-added Services
  • Product Tagging & Serialization
  • Product Kitting

The Highest Standards in High Temperature Thermocouples

Unparalleled manufacturing, testing, and calibration services for superior accuracy and reliability.

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