Bare Thermocouple Wire Features

• Full thermocouple range: K, N, E, J, T, S, R, and B thermocouple alloy pairs are available.
• Uninsulated construction: Bare positive and negative wires can be welded to form a measuring junction for custom sensor fabrication.
• Multiple diameters: Fine wires are available for fast response, while larger diameters provide greater mechanical strength and service life.
• IEC 60584-1 specifications: Wire can be supplied to applicable thermocouple reference functions and tolerance requirements.
• Flexible supply: Available by meter, spool, or custom cut length.
• Custom supply: Wire diameter, length, tolerance grade, matched-pair requirements, and quantity can be specified for OEM applications.

What Is Bare Thermocouple Wire?

Bare thermocouple wire consists of two dissimilar thermocouple alloy wires without an insulation layer. When the two conductors are joined at a measuring junction, a thermoelectric voltage is generated according to the temperature difference between the measuring junction and reference junction.

The wire can be used as the sensing element when manufacturing custom thermocouple probes. Ceramic beads, ceramic tubes, mica, or another suitable insulating structure can be added when electrical separation between the two conductors is required.

Main Applications

Bare thermocouple wire is commonly used for:

• Custom thermocouple sensor fabrication
• Laboratory temperature testing
• Furnace spot temperature measurement
• High-temperature research and development
• Vacuum and inert-gas equipment
• Special temperature probes
• Industrial temperature measurement systems

Supported Thermocouple Types

For help comparing K, J, T, E, N, S, R, and B thermocouple options, see our thermocouple types selection guide.

• K-Type: NiCr-NiSi
• N-Type: NiCrSi-NiSi
• E-Type: NiCr-CuNi
• J-Type: Fe-CuNi
• T-Type: Cu-CuNi
• S-Type: PtRh10-Pt
• R-Type: PtRh13-Pt
• B-Type: PtRh30-PtRh6

Technical Specifications

Wire Diameter

Available diameter options include 0.05 mm, 0.1 mm, 0.2 mm, 0.3 mm, 0.5 mm, 0.8 mm, 1.0 mm, 1.5 mm, 2.0 mm, 3.0 mm, and larger sizes up to 10 mm on request. Actual availability depends on the thermocouple type, alloy combination, and required mechanical or temperature performance.

Tolerance Grade

Wire can be supplied according to applicable requirements of IEC 60584-1, which specifies reference functions and tolerances for letter-designated thermocouple types.

• Class 2: Standard tolerance grade for general industrial applications
• Class 1: Tighter tolerance grade for applications requiring improved measurement accuracy

Thermocouple Wire Specification Table

Typical Service Temperature Guide

The following values are typical service guidance for bare thermocouple wire and are not universal limits defined by IEC 60584-1. Actual allowable temperature depends on thermocouple type, wire diameter, atmosphere, installation method, junction construction, and required service life. Standard thermocouple reference-function ranges are broader for some types, so the wire should be selected according to the actual application rather than the nominal type range alone.

Note: Fine-gauge wire generally has a lower usable continuous temperature. Reducing, corrosive, contaminated, or otherwise unsuitable atmospheres may further reduce service life and allowable temperature. For critical high-temperature applications, confirm the wire diameter, atmosphere, and required operating temperature before ordering.

Installation and Operation

1. Keep the two wires electrically separated. A short circuit between the positive and negative legs can cause incorrect temperature measurement.
2. Select the wire diameter according to the application. Fine wire provides faster thermal response, while larger wire offers better mechanical strength and durability.
3. Form a secure measuring junction. Spot welding or argon-arc welding can be used according to the sensor fabrication method.
4. Use suitable insulation when required. Ceramic beads, ceramic tubes, mica, or other suitable insulation can prevent accidental contact between the two conductors.
5. Select the atmosphere carefully. S, R, and B platinum-rhodium wire are generally intended for suitable oxidizing or inert environments and should not be operated long-term in reducing atmospheres.
6. Protect the wire from corrosive media. Bare wire should not be directly exposed to corrosive liquids or aggressive gases without suitable protection.

Bare Wire Supply Options

• Matched pairs: Positive and negative alloy wires can be supplied as a matched pair.
• Separate spools: Each conductor can be supplied on an individual spool.
• Meter supply: Suitable for laboratory and small-batch requirements.
• Full spool supply: Suitable for sensor manufacturers and industrial production.
• Custom cutting: Required lengths can be supplied according to application requirements.

How to Select Bare Thermocouple Wire

1. Select the thermocouple type according to the required temperature range and atmosphere.
2. Choose the wire diameter according to response time, mechanical strength, and expected service life.
3. Select Class 1 or Class 2 tolerance according to the measurement requirement.
4. Confirm whether the wire will be used directly or installed inside ceramic or another protective structure.
5. For OEM requirements, provide the thermocouple type, diameter, length, quantity, tolerance grade, and application environment.

Related Thermocouple Products

For complete temperature measurement solutions, see our related products:

• Industrial Thermocouples – complete thermocouple assemblies for industrial temperature measurement.
• Thermocouple Wire & Extension Cable – insulated extension and compensating cables for connecting thermocouples to temperature instruments.
• Thermocouple Applications – application information for industrial temperature measurement.

Request Custom Bare Thermocouple Wire

For custom or replacement requirements, please provide the thermocouple type, wire diameter, required length, tolerance grade, quantity, and application environment. Drawings, specifications, or existing samples are welcome.

Custom bare thermocouple wire is available for sensor fabrication, laboratory testing, furnace measurement, and OEM temperature sensing applications.