Thermocouple Wire Colors
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.
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 also have an extensive range of data sheets available for all our Thermocouple Grade Wire and Thermocouple Extension Wire.
Thermocouple Wire Colors, Ranges and Tolerances
| Thermocouple Type |
United States ANSI MC96.1 |
International
Color Code to IEC 60584-3 |
Temperature Range | Limits of Error* | |||
|---|---|---|---|---|---|---|---|
| Thermocouple Grade | Extension Grade | Thermocouple Grade | Extension Grade | Standard | Special | ||
| 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 |  |
 |
 |
-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 |  |
 |
 |
-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 |  |
 |
 |
-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 |  |
 |
 |
-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 | -- |  |
 |
-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 | -- | |
|
-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% |
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.
Thermocouple colors in Detail
What is the color Code for a Type K Thermocouple?
In the US, the most widely used color code for Type K thermocouples is to the ANSI MC96.1-1982 standard which is as follows:
Positive Leg = Yellow,
Negative Leg = Red,
Outer Sheath (Jacket) = Brown (thermocouple grade) or Yellow (extension grade),
Thermocouple Connector color = Yellow
Occasionally in the US, IEC colors may be found which have a green outer sheath with green and white conductors as shown above.
What is the color Code for a Type T Thermocouple?
In the US, the most widely used color code for Type T thermocouples is to the ANSI MC96.1-1982 standard which is as follows:
Positive Leg = Blue,
Negative Leg = Red,
Outer Sheath (Jacket) = Brown (thermocouple grade) or Blue (extension grade),
Thermocouple Connector color = Blue
Occasionally in the US, IEC colors may be found which have a blue outer sheath with blue and white conductors as shown above.
What is the color Code for a Type J Thermocouple?
In the US, the most widely used color code for Type J thermocouples is to the ANSI MC96.1-1982 standard which is as follows:
Positive Leg = White,
Negative Leg = Red,
Outer Sheath (Jacket) = Brown (thermocouple grade) or Black (extension grade),
Thermocouple Connector color = Black
Occasionally in the US, IEC colors may be found which have a black outer sheath with black and white conductors as shown above.
Further information on Type J Thermocouples
What is the color Code for a Type N Thermocouple?
In the US, the most widely used color code for Type N thermocouples is to the ASTM E 230 standard which is as follows:
Positive Leg = Orange,
Negative Leg = Red,
Outer Sheath (Jacket) = Brown (thermocouple grade) or Orange (extension grade),
Thermocouple Connector color = Orange
Occasionally in the US, IEC colors may be found which have a pink outer sheath with pink and white conductors as shown above.
What is the color Code for a Type E Thermocouple?
In the US, the most widely used color code for Type E thermocouples is to the ANSI MC96.1-1982 standard which is as follows:
Positive Leg = Purple,
Negative Leg = Red,
Outer Sheath (Jacket) = Brown (thermocouple grade) or Purple (extension grade),
Thermocouple Connector color = Purple
Occasionally in the US, IEC colors may be found which have a purple outer sheath with purple and white conductors as shown above.
What is the color Code for a Type S Thermocouple?
In the US, the most widely used color code for Type S thermocouples is to the ANSI MC96.1-1982 standard which is as follows:
Positive Leg = Black,
Negative Leg = Red,
Outer Sheath (Jacket) = Green (extension grade),
Thermocouple Connector color = Green
Occasionally in the US, IEC colors may be found which have a orange outer sheath with orange and white conductors as shown above.
What is the color Code for a Type R Thermocouple?
In the US, the most widely used color code for Type R thermocouples is to the ANSI MC96.1-1982 standard which is as follows:
Positive Leg = Black,
Negative Leg = Red,
Outer Sheath (Jacket) = Green (extension grade),
Thermocouple Connector color = Green
Occasionally in the US, IEC colors may be found which have a orange outer sheath with orange and white conductors as shown above.
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.
Thermocouple Grade Wire - Data Sheets
Flame Retardant PVC Insulated Thermocouple Wire
PFA Insulated Thermocouple Wire
Fiberglass Insulated PVC Insulated Thermocouple Wire
XLPE / MICA / Silicon Rubber and Kapton Thermocouple Wire
Thermocouple Extension Wire - Data Sheets
Flame Retardant PVC Insulated Thermocouple Extension Wire
PFA Insulated Thermocouple Extension Wire
Fiberglass Insulated PVC Insulated Thermocouple Extension Wire
XLPE / MICA / Silicon Rubber and Kapton Thermocouple Extension Wire
