Thermocouple Wire

We have over 5,000,000 feet of Thermocouple Wire available in PVC, PFA, Fiberglass insulation and more

We have large stocks of Thermocouple Wire (Cable) in all thermocouple types (K, J, T, N, R/S, E etc.) in PVC, Fiberglass, PFA, Silicone Rubber, XLPE and Ceramic Fiber insulation. Our thermocouple wire is ANSI standard color coded and to ANSI tolerances, although other color codes are also available. We offer stranded or solid wires in a wide variety of constructions from simple bellwire to screened and armored multipair types in complex configurations, supplied on any spool length required. Thermocouple wires are also available as bare solid conductors and an extensive range of RTD (Resistance Thermometer) Wire is also available in a wide variety of constructions.

We also have an extensive range of data sheets available for all our Thermocouple Grade Wire and Thermocouple Extension Wire.

Single Pair Insulated Thermocouple Wire - Thermocouple Grade and Extension Grade Wire

Heat Resistant
PVC Insulated
Heat Resistant PVC Insulated Thermocouple WireA wide range of HR PVC insulated Wire. constructions such as 'Parallel Construction', Twisted', Screened and Armored Wire is available.
Flame Retardant
PVC Insulated
Flame Retardant PVC Insulated Thermocouple CableFR PVC in Screened and Armored constructions. Meeting IEC 60332.1:2004 covering tests on Wire under fire conditions.
XLPE Low Smoke
and Fume
XLPE Extension GradeIncludes XLPE compound on the cores and LSF material on the bedding and/or outer sheath. For situations of fire risk and emissions.
Fire Resistant MICA/XLPE
Low Smoke and Fume
MICA / XLPE InsulatedFire Resistant MICA/XLPE Low Smoke and Fume Single Pairs. Incorporates high temperature MICA glass tape. Halogen free.
PFA Insulated Thermocouple Grade WireA wide range of PFA insulated Wire. constructions such as 'Parallel Construction', Twisted' and Screened Wire is available.
Fiberglass and Ceramic Fibre InsulatedHigh Temperature Fiberglass Insulated WireA range of 'Parallel Construction' and braided constructions in standard (480ºC) or High Temperature (800ºC) Fiberglass, Plus Ceramic Fibre (1400ºC). Flame Retardant
Silicone Rubber Insulated
Silicone Rubber InsulatedExcellent properties for the reduced propagation of flame by incorporation of flame retardant Silicone Rubber compounds in a range of constructions.
Kapton InsulatedFlame retardant with resistance to chemicals and radiation with excellent physical, electrical and mechanical properties over high temperatures
Stainless Steel
Braided Cables
Stainless Steel BraidedStainless Steel Braided PVC, PFA and Fiberglass insulated cables.
One pair of solid conductors.
Cores HR PVC insulated.
Pair Parallel and welded together in a ‘ripcord’ construction.
Parallel Construction
One pair of solid or stranded conductors. Cores HR PVC insulated. Pair Parallel.
HR PVC sheathed overall.
Stainless Steel Braided
HR PVC Parallel Construction
One pair of stranded conductors. Cores HR PVC insulated. Pair laid flat. HR PVC sheathed. Stainless steel braided overall.

Multipair Insulated Thermocouple Extension Wire

Flame Retardant
PVC Insulated

PVC Insulated Multipair CableA range of solid or stranded mulipair Wire with an individual and collective screen. HR PVC insulated from 2 to 50 pairs. Armored or Non Armored.

XLPE Low Smoke FR
and Fume

XLPE Insulated Multipair WireA range of stranded multipair Wire with an individual and collective screen. XLPE insulated from 2 to 36 pairs. Armored or Non Armored.


PFA Insulated Multipair Thermocouple Extension gradeA range of stranded multipair Wire with a collective screen with or without steel wire braid. PFA insulated from 2 to 12 pairs.


ANSI Fiberglass Insulated MultipairA range of stranded multipair Wire, glass fibre insulated, with or without steel wire braid. Suitable for use up to 480ºC. From 2 to 12 pairs.

for use with Type K

Type K
Thermocouple Wires
HR PVC Thermocouple CablesA wide range of Type K thermocouple wire, single and multipair, in PVC, PFA, Fiberglass and Kapton insulation.

Thermocouple Grade Wire or Extension Grade Wire?

Thermocouple Wire (cable) is available in two grades; Thermocouple Grade wire & Extension Grade wire. Typically, thermocouple grade is used to make the actual thermocouple sensor or sensing point (junction) itself (detailed information on thermocouple sensor theory is available here), whereas thermocouple extension wire (cable) is used to connect thermocouple sensors to associated instrumentation systems, usually via an industrial terminal enclosure or thermocouple connector.

Extension wire will generally be of a lower grade than thermocouple wire and should not be used to make the sensor itself and should only be used to extend thermocouples. However, thermocouple grade wire can be used either to make the sensing junction (sensor) or used as extension cable and will usually have a higher ambient temperature range (subject to the insulation type). Our thermocouple grade cables are identified using the thermocouple type letter e.g. KK, JJ, TT etc. and extension grades are designated with an 'x' e.g. KX, JX, TX etc.

Thermocouple Wire Identification

Insulated Thermocouple Wire combinations use guidelines according to ANSI color coding. You will see in the table below, that commonly, negative wires are red, the outer sheath for thermocouple grades is brown and the positive lead is color coded according to thermocouple type. For extension grade cables this positive leg color is also carried over to the outer insulation color. Fiberglass insulated wires follow the same system but have a colored tracer rather than a solid color.

Insulation Color Codes, Ranges and Tolerances

United States
International Color Code
to IEC 60584-3
Temperature Range Limits of Error*
Thermocouple Grade Extension Grade Thermocouple Grade Extension Grade Standard Special
K ANSI MC96.1 Type K Thermocouple Wire Thermocouple Wire IEC K -454 to 2300°F
-270 to 1260°C
32 to 392°F
0 to 200°C
±2.2°C or ±0.75% ±1.1°C or 0.4%
T Thermocouple Wire  Type T Thermocouple Wire TX Thermocouple Wire IEC T -454 to 700°F
-270 to 370°C
32 to 392°F
0 to 200°C
±1.0°C or ±0.75% ±0.5°C or 0.4%
J Thermocouple Wire JJ Thermocouple Wire JX Thermocouple Wire IEC J -346 to 1400°F
-210 to 760°C
32 to 392°F
0 to 200°C
±2.2°C or ±0.75% ±1.1°C or 0.4%
N Thermocouple Wire NN Thermocouple Wire NX Thermocouple Wire IEC N -454 to 2300°F
-270 to 1260°C
32 to 392°F
0 to 200°C
±2.2°C or ±0.75% ±1.1°C or 0.4%
E Thermocouple Wire EE Thermocouple Wire EX Thermocouple Wire IEC E -454 to 1600°F
-270 to 870°C
32 to 392°F
0 to 200°C
±1.7°C or ±0.5% ±1.0°C or ±0.4%
S -- Thermocouple Wire SX Thermocouple Wire IEC S -58 to 2700°F
-50 to 1480°C
32 to 392°F
0 to 200°C
±1.5°C or ±0.25% ±0.6°C or ±0.1%
R -- Thermocouple Wire RX Thermocouple Wire IEC R -58 to 2700°F
-50 to 1480°C
32 to 392°F
0 to 200°C
±1.5°C or ±0.25% ±0.6°C or ±0.1%

* whichever is greater

Thermocouple extension wire is manufactured from conductors having approximately the same thermoelectric characteristics as thermocouple wire but the accuracy is for a more limited range. Extension wire can offer a cost advantage.
For base metal thermocouples, the wire is the same composition as the corresponding thermocouple.
For noble metal thermocouples, the wire is an entirely different alloy which matches the noble metal characteristics over a specified temperature range.

The maximum temperatures are limited by the type of insulation used.

What are Special Limits of Error (SLE) and Standard Limits of Error?

As can be seen from the table above, there are two accuracy classes of wire available. Cables with a Standard Limit of Error use standard thermocouple grade wire and this accuracy grade is suitable for the majority of uses. However, certain applications require a higher accuracy and so use cables with a Special Limit of Error (SLE). These wires use a purer form of the thermocouple alloys which in turn improve the accuracy as listed above.

As a company speciliaising the manufacturer of custom built thermocouples, TC can offer cable or complete assemblies made using SLE wire.

Color Codes and Tolerances for Thermocouple Wires and Extension Wire

IEC 60584-3 provides tolerances and identification for a common international system for thermocouple wire identification and tolerances based essentially on thermoelectric emf as opposed to a datum of the emf of the thermo elements against platinum. Tolerances are defined as the maximum allowable deviation in microvolts, caused by the introduction of extension or compensating extension wire into the circuit. Color codes and tolerances are well established in the United States and have been in use as a national standard for years. In other parts of the world, there are alternative color code systems and tolerances, either in use, or in the process of being implemented. One such color code system is that established by the IEC.

In the United States, color codes and tolerances are defined in ANSI 96.1 (1982) and ASTM E-230. Extension wire and compensating extension wire is indicated with the letter “X” after the thermocouple type per these standards.

The color code for thermocouple grade wire includes a brown overall jacket whereas the color code for thermocouple extension wire typically includes an overall jacket in the color of the positive wire. For some insulations, colors may appear as a stripe or trace strand. High temperature braided insulation is not normally color coded. The table above shows the color coding adopted by the ASTM and IEC.

Wire Insulation Materials

There is a wide choice of insulation materials, the choice of which is governed by the application and the ambient temperature wires will be exposed to:

Heat Resistant PVC Insulated Wire

Heat Resistant (HR) PVC is a popular choice for general use in the temperature range -22ºF to +220ºF. It is available in a wide variety of constructions from simple bellwire to shielded and armored types in virtually all of the thermocouple combinations. Flame Retardant PVC is also available.

PFA Insulated Wire

PFA is ideal for higher temperature applications up to 480ºF when PVC is not adequate. It is also excellent for temperatures down to -100ºF.

PFA will withsatnd attack from virtually all known chemicals, oils and fluids. All our PFA cables are made in extruded form and are therefore gas, steam and water tight which makes them most suitable for applicatiins such as autoclaves or sterilizers. We offer a wide variety of constructions from simple twisted pairs to shielded types in virtually all of the thermocouple combinations.

Fiberglass and Ceramic Fiber Insulated Wire

Excellent for high temperature applications up to 900ºF for Fiberglass, and 1475ºF for High Temperature Fiberglass and 2200ºF for Ceramic Fiber. They are suitable for use at normal air ambient temperatures where there is a possibility of a hot spot which might damage lower rated cables such as PVC or PFA.

We offer a wide variety of constructions from simple lapped and fiberglass braided to stainless steel braided types in virtually all of the thermocouple combinations.

XLPE Insulated Wire

These cables incorporate XLPE (Cross Linked Polyethylene) compound on the conductors and Low Smoke and Fume (LSF) material on the bedding and/or outer sheath. They meet the requirements of IEC60332.3 covering tests on cables under fire conditions and are ideal for situations where there is a risk of fire and the emission of smoke and gases could threaten life and property. The sheathing materials used are Halogen free and the acidic gas which is evolved during combustion is less than 0.5% in accordance with IEC 60754-1. The mechanical properties of these cables meet the requirements of IEC 60811.

MICA/XLPE Insulated Wire

Resistant to a temperature of 1380°F for at least three hours in accordance with the flame test requirements of IEC 60331. These cables are essential for situations where it is of strategic importance to ensure that the cable continues to function during a major crisis involving fire. The cable incorporates a high temperature rated Mica glass tape with a XLPE (Cross Linked Polyethylene) insulation on the conductors and Low Smoke and Fume material on the bedding and/or outer sheath. Sheathing materials are Halogen free.


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Thermocouple Sensors
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PVC Multipair Thermocouple Wire
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Fiberglass Multipair Thermocouple Wire
PVC RTD Pt100 Wire
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