A thermocouple's type letter (J, K, T, E, N, R, S, B, C...) names an alloy pair, but the wire color that identifies it on the bench is set by a different standards body depending on where the part was made or bought — ANSI/ASTM MC96.1 uses one color code, IEC 60584-3 (and JIS C 1602 in Japan) uses a different one for the same alloy pair, and the two schemes disagree on which color means positive. Nobody publishes the type letter, both color codes, the alloy pair and the accuracy tolerance class on one page; a buyer or field technician instead has to hold two vendor charts side by side and hope the type letters line up. A record here is one thermocouple type with its positive/negative alloy names, ANSI positive/negative wire color, IEC positive/negative wire color, usable temperature range, and its ASTM E230 standard/special-limits tolerance alongside its IEC 60584-2 / JIS C 1602 class 1/2/3 tolerance. Answers 'is red positive or negative on a type K thermocouple', 'what color is IEC type J versus ANSI type J', 'what's the accuracy tolerance on a class 2 type N thermocouple', and 'my probe has a yellow and red wire, what type is it and is that ANSI or IEC'.

The alloy pairs, wire colors and tolerance values are the content of published standards (ASTM E230/E230M, ANSI MC96.1, IEC 60584-2/-3, JIS C 1602) which are themselves sold documents; the facts within them are not copyrightable and every vendor reference chart already republishes them for exactly this reason. Each record quotes a short verbatim span from the vendor's own reproduction and links back to it, rather than reproducing or selling the standard itself.

Thermocouple type letter to alloy pair, ANSI/IEC color code and tolerance class


**Type letter:** B

**Usable temperature range:** 0 to 1820°C

**Source document:** ANSI and IEC Color Codes

> B B Do Not Insert in Metal NONE – PLATINUM- Platinum- Tubes. Beware of – – Contamination. 0 to 1820°C 0 to 13.820 ESTABLISHED 30% RHODIUM 6% RHODIUM High Temp. Common Use 32 to 3308°F Pt-30% Rh Pt-6% Rh in Glass Industry

Source: <https://assets.omega.com/pdf/test-and-measurement-equipment/temperature/sensors/thermocouple-probes/tc_colorcodes.pdf>

B — Thermocouple type letter to alloy pair, ANSI/IEC color code and tolerance class


**Type letter:** B

**IEC 60584-3 positive-leg color:** Grey

**IEC 60584-3 negative-leg color:** White

**IEC 60584-3 outer sheath colour:** Grey

**Source document:** Thermocouple Colour Code Standards

> What is the Colour Code for a Type B Thermocouple? In the UK and Europe, the most widely used colour code for Type B thermocouple cable is to the international IEC 60584-3 standard which is as follows: Positive Leg = Grey, Negative Leg = White, Outer Sheath (Jacket) = Grey, Thermocouple Connector Colour = Grey

Source: <https://www.tc.co.uk/thermocouple-information/thermocouple-colour-code.html>


**Type letter:** B

**Positive-leg alloy:** Platinum 30% rhodium

**Negative-leg alloy:** Platinum 6% rhodium

**ANSI/ASTM positive-leg color:** Gray

**ANSI/ASTM negative-leg color:** Red

**ANSI extension-grade jacket color:** Gray

**Source document:** ANSI/ASTM Thermocouple Color Codes

> Type | Positive conductor | Negative conductor | Positive color | Negative color | Extension-grade jacket | Thermocouple-grade jacket shown in legacy assets | T | Copper | Constantan | Blue | Red | Blue | Brown | J | Iron | Constantan | White | Red | Black | Brown | E | Chromel | Constantan | Purple | Red | Purple | Brown | K | Chromel | Alumel | Yellow | Red | Yellow | Brown | N | Nicrosil | Nisil | Orange | Red | Orange | Brown | S | Platinum 10% rhodium | Pure platinum | Black | Red | Green | None established in legacy asset | R | Platinum 13% rhodium | Pure platinum | Black | Red | Green | None established in legacy asset | B | Platinum 30% rhodium | Platinum 6% rhodium | Gray | Red | Gray | None established in legacy asset |

Source: <https://thermometricscorp.com/thermocouple-color-codes.html>


**Type letter:** C

**Usable temperature range:** 0 to 2320°C

**Source document:** ANSI and IEC Color Codes

> C* C Vacuum, Inert, Hydrogen. NONE + TUNGSTEN- TUNGSTEN- Beware of Embrittlement. NO STANDARD – 5% RHENIUM 26% RHENIUM Not Practical Below 0 to 2320°C USE ANSI ESTABLISHED 399°C (750°F) 32 to 4208°F 0 to 37.066 W-5% Re W-26% Re COLOR CODE (W5) Not for Oxidizing Atmosphere (W5)

Source: <https://assets.omega.com/pdf/test-and-measurement-equipment/temperature/sensors/thermocouple-probes/tc_colorcodes.pdf>

C — Thermocouple type letter to alloy pair, ANSI/IEC color code and tolerance class


**Type letter:** C

**IEC 60584-3 positive-leg color:** Red

**IEC 60584-3 negative-leg color:** White

**IEC 60584-3 outer sheath colour:** Red

**Source document:** Thermocouple Colour Code Standards

> What is the Colour Code for a Type C Thermocouple? In the UK and Europe, the official colour code for Type C thermocouple cable is to the international IEC 60584-3 standard which is as follows: Positive Leg = Red * Negative Leg = White * Outer Sheath (Jacket) = Red

Source: <https://www.tc.co.uk/thermocouple-information/thermocouple-colour-code.html>


**Type letter:** C

**Positive-leg alloy:** Tungsten 5% rhenium

**Negative-leg alloy:** Tungsten 26% rhenium

**ANSI/ASTM positive-leg color:** Green

**ANSI/ASTM negative-leg color:** Red

**ANSI extension-grade jacket color:** Red

**Source document:** ANSI/ASTM Thermocouple Color Codes

> Type | Positive conductor | Negative conductor | Positive color | Negative color | Extension-grade jacket | Thermocouple-grade jacket shown in legacy assets | T | Copper | Constantan | Blue | Red | Blue | Brown | J | Iron | Constantan | White | Red | Black | Brown | E | Chromel | Constantan | Purple | Red | Purple | Brown | K | Chromel | Alumel | Yellow | Red | Yellow | Brown | N | Nicrosil | Nisil | Orange | Red | Orange | Brown | S | Platinum 10% rhodium | Pure platinum | Black | Red | Green | None established in legacy asset | R | Platinum 13% rhodium | Pure platinum | Black | Red | Green | None established in legacy asset | B | Platinum 30% rhodium | Platinum 6% rhodium | Gray | Red | Gray | None established in legacy asset | C | Tungsten 5% rhenium | Tungsten 26% rhenium | Green | Red | Red | Unjacketed conductors shown in legacy asset |

Source: <https://thermometricscorp.com/thermocouple-color-codes.html>


**Type letter:** D

**Usable temperature range:** 0 to 2320°C

**Source document:** ANSI and IEC Color Codes

> D* D Vacuum, Inert, Hydrogen. + TUNGSTEN- TUNGSTEN- Beware of Embrittlement. Not Practical Below NO STANDARD NONE 0 to 2320°C USE ANSI – 3% RHENIUM 25% RHENIUM 399°C (750°F)–Not for ESTABLISHED W-3% Re W-25% Re 32 to 4208°F 0 to 39.506 COLOR CODE (W3) Oxidizing Atmosphere (W3)

Source: <https://assets.omega.com/pdf/test-and-measurement-equipment/temperature/sensors/thermocouple-probes/tc_colorcodes.pdf>

D — Thermocouple type letter to alloy pair, ANSI/IEC color code and tolerance class


**Type letter:** E

**IEC 60584 Class 1 tolerance:** –40°C to +375°C ±1.5°C 375°C to 800°C ±0.004⋅ |t|

**IEC 60584 Class 2 tolerance:** –40°C to +333°C ±2.5°C 333°C to 900°C ±0.0075 ⋅ |t|

**Source document:** Thermocouple Tolerances

> Thermocouple Output Tolerances to IEC 60584-1 | Type | + Leg | - Leg | 100ºC | 500ºC | 1000ºC | Continuous | Short Term | Type | Class 1 | Class 2 | K | NICKEL - CHROMIUM Also known as: Chromel™, Thermokanthal KP*, NiCr, T1*, Tophel™ | NICKEL - Aluminum (magnetic) Also known as: Ni-Al, Alumel™, Thermokanthal KN™, T2™, NiAl™ | 42 | 43 | 39 | 0 to +1100ºC | -180 to +1350ºC | Temperature Range Tolerance Value Temperature Range Tolerance Value | –40°C to +375°C ±1.5°C 375°C to 1000°C ±0.004 ⋅ |t| | –40°C to +333°C ±2.5°C 333°C to 1200°C ±0.0075 ⋅ |t| | T | COPPER | COPPER - NICKEL Also known as: Constantan, Advance™, Cupron™ | 46 | – | – | –185 to +300°C | –250 to +400°C | Temperature Range Tolerance Value Temperature Range Tolerance Value | –40°C to +125°C ±0.5°C 125°C to 350°C ±0.004⋅ |t| | –40°C to +133°C ±1.0°C 133°C to 350°C ±0.0075 ⋅ |t| | J | IRON (magnetic) Also known as: Fe | COPPER - NICKEL Also known as: Nickel-Copper, Constantan, Advance™, Cupron™ | 54 | 56 | 59 | +20 to +700°C | –180 to +750°C | Temperature Range Tolerance Value Temperature Range Tolerance Value | –40°C to +375°C ±1.5°C 375°C to 750°C ±0.004⋅ |t| | –40°C to +333°C ±2.5°C 333°C to 750°C ±0.0075 ⋅ |t| | N | NICKEL - CHROMIUM -SILICON Also known as: Nicrosil | NICKEL - SILICON - MAGNESIUM Also known as: Nisil | 30 | 38 | 39 | 0 to +1150ºC | -270 to +1300ºC | Temperature Range Tolerance Value Temperature Range Tolerance Value | –40°C to +375°C ±1.5°C 375°C to 1000°C ±0.004⋅ |t| | –40°C to +333°C ±2.5°C 333°C to 1200°C ±0.0075⋅ |t| | E | NICKEL - CHROMIUM Also known as: Chromel™, Tophel™, Chromium, Nickel | NICKEL - Aluminum Also known as: Nickel-Copper, Constantan, Advance™, Cupron™ | 68 | 81 | – | 0 to +800ºC | -40 to +900ºC | Temperature Range Tolerance Value Temperature Range Tolerance Value | –40°C to +375°C ±1.5°C 375°C to 800°C ±0.004⋅ |t| | –40°C to +333°C ±2.5°C 333°C to 900°C ±0.0075 ⋅ |t|

Source: <https://www.tc-inc.com/thermocouple/thermocouple-tolerances.html>

E — Thermocouple type letter to alloy pair, ANSI/IEC color code and tolerance class


**Type letter:** E

**Usable temperature range:** –270 to 1000°C

**Source document:** ANSI and IEC Color Codes

> CHROMEGA® Oxidizing or Inert. + + E E CONSTANTAN Limited Use in Vacuum or –270 to 1000°C –9.835 to – – NICKEL- COPPER- Reducing. Highest EMF –454 to 1832°F 76.373 – – CHROMIUM NICKEL Change Ni-Cr Cu-Ni Per Degree

Source: <https://assets.omega.com/pdf/test-and-measurement-equipment/temperature/sensors/thermocouple-probes/tc_colorcodes.pdf>


**Type letter:** E

**IEC 60584-3 positive-leg color:** Purple

**IEC 60584-3 negative-leg color:** White

**IEC 60584-3 outer sheath colour:** Purple

**Source document:** Thermocouple Colour Code Standards

> What is the Colour Code for a Type E Thermocouple? In the UK and Europe, the most widely used colour code for Type E thermocouple cable is to the international IEC 60584-3 standard which is as follows: Positive Leg = Purple, Negative Leg = White, Outer Sheath (Jacket) = Purple, Thermocouple Connector Colour = Purple

Source: <https://www.tc.co.uk/thermocouple-information/thermocouple-colour-code.html>


**Type letter:** E

**Positive-leg alloy:** Chromel

**Negative-leg alloy:** Constantan

**ANSI/ASTM positive-leg color:** Purple

**ANSI/ASTM negative-leg color:** Red

**ANSI extension-grade jacket color:** Purple

**Source document:** ANSI/ASTM Thermocouple Color Codes

> Type | Positive conductor | Negative conductor | Positive color | Negative color | Extension-grade jacket | Thermocouple-grade jacket shown in legacy assets | T | Copper | Constantan | Blue | Red | Blue | Brown | J | Iron | Constantan | White | Red | Black | Brown | E | Chromel | Constantan | Purple | Red | Purple | Brown |

Source: <https://thermometricscorp.com/thermocouple-color-codes.html>


**Type letter:** G

**Usable temperature range:** 0 to 2320°C

**Source document:** ANSI and IEC Color Codes

> G* Vacuum, Inert, Hydrogen. NONE ESTABLISHED + – TUNGSTEN W TUNGSTEN- 26% RHENIUM Beware of Embrittlement. Not Practical Below 399°C (750°F). 0 to 2320°C 0 to 38.564 NO STANDARD USE ANSI COLOR CODE G (W) W-26% Re Not for Oxidizing Atmosphere 32 to 4208°F (W)

Source: <https://assets.omega.com/pdf/test-and-measurement-equipment/temperature/sensors/thermocouple-probes/tc_colorcodes.pdf>

G — Thermocouple type letter to alloy pair, ANSI/IEC color code and tolerance class


**Type letter:** J

**IEC 60584 Class 1 tolerance:** –40°C to +375°C ±1.5°C 375°C to 750°C ±0.004⋅ |t|

**IEC 60584 Class 2 tolerance:** –40°C to +333°C ±2.5°C 333°C to 750°C ±0.0075 ⋅ |t|

**Source document:** Thermocouple Tolerances

> Thermocouple Output Tolerances to IEC 60584-1 | Type | + Leg | - Leg | 100ºC | 500ºC | 1000ºC | Continuous | Short Term | Type | Class 1 | Class 2 | K | NICKEL - CHROMIUM Also known as: Chromel™, Thermokanthal KP*, NiCr, T1*, Tophel™ | NICKEL - Aluminum (magnetic) Also known as: Ni-Al, Alumel™, Thermokanthal KN™, T2™, NiAl™ | 42 | 43 | 39 | 0 to +1100ºC | -180 to +1350ºC | Temperature Range Tolerance Value Temperature Range Tolerance Value | –40°C to +375°C ±1.5°C 375°C to 1000°C ±0.004 ⋅ |t| | –40°C to +333°C ±2.5°C 333°C to 1200°C ±0.0075 ⋅ |t| | T | COPPER | COPPER - NICKEL Also known as: Constantan, Advance™, Cupron™ | 46 | – | – | –185 to +300°C | –250 to +400°C | Temperature Range Tolerance Value Temperature Range Tolerance Value | –40°C to +125°C ±0.5°C 125°C to 350°C ±0.004⋅ |t| | –40°C to +133°C ±1.0°C 133°C to 350°C ±0.0075 ⋅ |t| | J | IRON (magnetic) Also known as: Fe | COPPER - NICKEL Also known as: Nickel-Copper, Constantan, Advance™, Cupron™ | 54 | 56 | 59 | +20 to +700°C | –180 to +750°C | Temperature Range Tolerance Value Temperature Range Tolerance Value | –40°C to +375°C ±1.5°C 375°C to 750°C ±0.004⋅ |t| | –40°C to +333°C ±2.5°C 333°C to 750°C ±0.0075 ⋅ |t|

Source: <https://www.tc-inc.com/thermocouple/thermocouple-tolerances.html>

J — Thermocouple type letter to alloy pair, ANSI/IEC color code and tolerance class


**Type letter:** J

**Usable temperature range:** –210 to 1200°C

**Source document:** ANSI and IEC Color Codes

> J J IRON CONSTANTAN – Fe COPPER- in Oxidizing at High – – Temperatures. –210 to 1200°C –8.095 to – (magnetic) NICKEL Not Recommended for –346 to 2193°F 69.553 Cu-Ni Low Temperatures.

Source: <https://assets.omega.com/pdf/test-and-measurement-equipment/temperature/sensors/thermocouple-probes/tc_colorcodes.pdf>


**Type letter:** J

**IEC 60584-3 positive-leg color:** Black

**IEC 60584-3 negative-leg color:** White

**IEC 60584-3 outer sheath colour:** Black

**Source document:** Thermocouple Colour Code Standards

> What is the Colour Code for a Type J Thermocouple? In the UK and Europe, the most widely used colour code for Type J thermocouple cable is to the international IEC 60584-3 standard which is as follows: Positive Leg = Black, Negative Leg = White, Outer Sheath (Jacket) = Black, Thermocouple Connector Colour = Black

Source: <https://www.tc.co.uk/thermocouple-information/thermocouple-colour-code.html>


**Type letter:** J

**Positive-leg alloy:** Iron

**Negative-leg alloy:** Constantan

**ANSI/ASTM positive-leg color:** White

**ANSI/ASTM negative-leg color:** Red

**ANSI extension-grade jacket color:** Black

**Source document:** ANSI/ASTM Thermocouple Color Codes

> Type | Positive conductor | Negative conductor | Positive color | Negative color | Extension-grade jacket | Thermocouple-grade jacket shown in legacy assets | T | Copper | Constantan | Blue | Red | Blue | Brown | J | Iron | Constantan | White | Red | Black | Brown |

Source: <https://thermometricscorp.com/thermocouple-color-codes.html>


**Type letter:** K

**IEC 60584 Class 1 tolerance:** –40°C to +375°C ±1.5°C 375°C to 1000°C ±0.004 ⋅ |t|

**IEC 60584 Class 2 tolerance:** –40°C to +333°C ±2.5°C 333°C to 1200°C ±0.0075 ⋅ |t|

**Source document:** Thermocouple Tolerances

> Thermocouple Output Tolerances to IEC 60584-1 | Type | + Leg | - Leg | 100ºC | 500ºC | 1000ºC | Continuous | Short Term | Type | Class 1 | Class 2 | K | NICKEL - CHROMIUM Also known as: Chromel™, Thermokanthal KP*, NiCr, T1*, Tophel™ | NICKEL - Aluminum (magnetic) Also known as: Ni-Al, Alumel™, Thermokanthal KN™, T2™, NiAl™ | 42 | 43 | 39 | 0 to +1100ºC | -180 to +1350ºC | Temperature Range Tolerance Value Temperature Range Tolerance Value | –40°C to +375°C ±1.5°C 375°C to 1000°C ±0.004 ⋅ |t| | –40°C to +333°C ±2.5°C 333°C to 1200°C ±0.0075 ⋅ |t|

Source: <https://www.tc-inc.com/thermocouple/thermocouple-tolerances.html>

K — Thermocouple type letter to alloy pair, ANSI/IEC color code and tolerance class


**Type letter:** K

**Usable temperature range:** –270 to 1372°C

**Source document:** ANSI and IEC Color Codes

> ALOMEGA ® Clean Oxidizing and Inert. + + CHROMEGA ® + + K K Limited Use in Vacuum NICKEL- NICKEL- – – ALUMINUM or Reducing. Wide –270 to 1372°C –6.458 to – – CHROMIUM Temperature Ni-AI Range, Most Popular –454 to 2501°F 54.886 Ni-Cr (magnetic) H Calibration

Source: <https://assets.omega.com/pdf/test-and-measurement-equipment/temperature/sensors/thermocouple-probes/tc_colorcodes.pdf>


**Type letter:** K

**IEC 60584-3 positive-leg color:** Green

**IEC 60584-3 negative-leg color:** White

**IEC 60584-3 outer sheath colour:** Green

**Source document:** Thermocouple Colour Code Standards

> What is the Colour Code for a Type K Thermocouple? In the UK and Europe, the most widely used colour code for Type K thermocouple cable is to the international IEC 60584-3 standard which is as follows: Positive Leg = Green, Negative Leg = White, Outer Sheath (Jacket) = Green, Thermocouple Connector Colour = Green

Source: <https://www.tc.co.uk/thermocouple-information/thermocouple-colour-code.html>


**Type letter:** K

**Positive-leg alloy:** Chromel

**Negative-leg alloy:** Alumel

**ANSI/ASTM positive-leg color:** Yellow

**ANSI/ASTM negative-leg color:** Red

**ANSI extension-grade jacket color:** Yellow

**Source document:** ANSI/ASTM Thermocouple Color Codes

> Type | Positive conductor | Negative conductor | Positive color | Negative color | Extension-grade jacket | Thermocouple-grade jacket shown in legacy assets | T | Copper | Constantan | Blue | Red | Blue | Brown | J | Iron | Constantan | White | Red | Black | Brown | E | Chromel | Constantan | Purple | Red | Purple | Brown | K | Chromel | Alumel | Yellow | Red | Yellow | Brown |

Source: <https://thermometricscorp.com/thermocouple-color-codes.html>


**Type letter:** N

**IEC 60584 Class 1 tolerance:** –40°C to +375°C ±1.5°C 375°C to 1000°C ±0.004⋅ |t|

**IEC 60584 Class 2 tolerance:** –40°C to +333°C ±2.5°C 333°C to 1200°C ±0.0075⋅ |t|

**Source document:** Thermocouple Tolerances

> Thermocouple Output Tolerances to IEC 60584-1 | Type | + Leg | - Leg | 100ºC | 500ºC | 1000ºC | Continuous | Short Term | Type | Class 1 | Class 2 | K | NICKEL - CHROMIUM Also known as: Chromel™, Thermokanthal KP*, NiCr, T1*, Tophel™ | NICKEL - Aluminum (magnetic) Also known as: Ni-Al, Alumel™, Thermokanthal KN™, T2™, NiAl™ | 42 | 43 | 39 | 0 to +1100ºC | -180 to +1350ºC | Temperature Range Tolerance Value Temperature Range Tolerance Value | –40°C to +375°C ±1.5°C 375°C to 1000°C ±0.004 ⋅ |t| | –40°C to +333°C ±2.5°C 333°C to 1200°C ±0.0075 ⋅ |t| | T | COPPER | COPPER - NICKEL Also known as: Constantan, Advance™, Cupron™ | 46 | – | – | –185 to +300°C | –250 to +400°C | Temperature Range Tolerance Value Temperature Range Tolerance Value | –40°C to +125°C ±0.5°C 125°C to 350°C ±0.004⋅ |t| | –40°C to +133°C ±1.0°C 133°C to 350°C ±0.0075 ⋅ |t| | J | IRON (magnetic) Also known as: Fe | COPPER - NICKEL Also known as: Nickel-Copper, Constantan, Advance™, Cupron™ | 54 | 56 | 59 | +20 to +700°C | –180 to +750°C | Temperature Range Tolerance Value Temperature Range Tolerance Value | –40°C to +375°C ±1.5°C 375°C to 750°C ±0.004⋅ |t| | –40°C to +333°C ±2.5°C 333°C to 750°C ±0.0075 ⋅ |t| | N | NICKEL - CHROMIUM -SILICON Also known as: Nicrosil | NICKEL - SILICON - MAGNESIUM Also known as: Nisil | 30 | 38 | 39 | 0 to +1150ºC | -270 to +1300ºC | Temperature Range Tolerance Value Temperature Range Tolerance Value | –40°C to +375°C ±1.5°C 375°C to 1000°C ±0.004⋅ |t| | –40°C to +333°C ±2.5°C 333°C to 1200°C ±0.0075⋅ |t|

Source: <https://www.tc-inc.com/thermocouple/thermocouple-tolerances.html>

N — Thermocouple type letter to alloy pair, ANSI/IEC color code and tolerance class


**Type letter:** N

**Usable temperature range:** –270 to 1300°C

**Source document:** ANSI and IEC Color Codes

> Alternative + + N N OMEGA-P® OMEGA-N® to Type K. –270 to 1300°C –4.345 – – NICROSIL – – NISIL More Stable –450 to 2372°F to 47.513 Ni-Cr-Si Ni-Si-Mg at High Temps

Source: <https://assets.omega.com/pdf/test-and-measurement-equipment/temperature/sensors/thermocouple-probes/tc_colorcodes.pdf>


**Type letter:** N

**IEC 60584-3 positive-leg color:** Pink

**IEC 60584-3 negative-leg color:** White

**IEC 60584-3 outer sheath colour:** Pink

**Source document:** Thermocouple Colour Code Standards

> What is the Colour Code for a Type N Thermocouple? In the UK and Europe, the most widely used colour code for Type N thermocouple cable is to the international IEC 60584-3 standard which is as follows: Positive Leg = Pink, Negative Leg = White, Outer Sheath (Jacket) = Pink, Thermocouple Connector Colour = Pink

Source: <https://www.tc.co.uk/thermocouple-information/thermocouple-colour-code.html>


**Type letter:** N

**Positive-leg alloy:** Nicrosil

**Negative-leg alloy:** Nisil

**ANSI/ASTM positive-leg color:** Orange

**ANSI/ASTM negative-leg color:** Red

**ANSI extension-grade jacket color:** Orange

**Source document:** ANSI/ASTM Thermocouple Color Codes

> Type | Positive conductor | Negative conductor | Positive color | Negative color | Extension-grade jacket | Thermocouple-grade jacket shown in legacy assets | T | Copper | Constantan | Blue | Red | Blue | Brown | J | Iron | Constantan | White | Red | Black | Brown | E | Chromel | Constantan | Purple | Red | Purple | Brown | K | Chromel | Alumel | Yellow | Red | Yellow | Brown | N | Nicrosil | Nisil | Orange | Red | Orange | Brown |

Source: <https://thermometricscorp.com/thermocouple-color-codes.html>


**Type letter:** R

**IEC 60584 Class 1 tolerance:** 0°C to +1100°C ±1.0°C 1100°C to 1600°C ±(1 +0.003 (t ⋅ 1100)°C

**IEC 60584 Class 2 tolerance:** 0°C to +600°C ±1.5°C 600°C to 1600°C ±0.0025 ⋅ |t|

**Source document:** Thermocouple Tolerances

> Thermocouple Output Tolerances to IEC 60584-1 | Type | + Leg | - Leg | 100ºC | 500ºC | 1000ºC | Continuous | Short Term | Type | Class 1 | Class 2 | K | NICKEL - CHROMIUM Also known as: Chromel™, Thermokanthal KP*, NiCr, T1*, Tophel™ | NICKEL - Aluminum (magnetic) Also known as: Ni-Al, Alumel™, Thermokanthal KN™, T2™, NiAl™ | 42 | 43 | 39 | 0 to +1100ºC | -180 to +1350ºC | Temperature Range Tolerance Value Temperature Range Tolerance Value | –40°C to +375°C ±1.5°C 375°C to 1000°C ±0.004 ⋅ |t| | –40°C to +333°C ±2.5°C 333°C to 1200°C ±0.0075 ⋅ |t| | T | COPPER | COPPER - NICKEL Also known as: Constantan, Advance™, Cupron™ | 46 | – | – | –185 to +300°C | –250 to +400°C | Temperature Range Tolerance Value Temperature Range Tolerance Value | –40°C to +125°C ±0.5°C 125°C to 350°C ±0.004⋅ |t| | –40°C to +133°C ±1.0°C 133°C to 350°C ±0.0075 ⋅ |t| | J | IRON (magnetic) Also known as: Fe | COPPER - NICKEL Also known as: Nickel-Copper, Constantan, Advance™, Cupron™ | 54 | 56 | 59 | +20 to +700°C | –180 to +750°C | Temperature Range Tolerance Value Temperature Range Tolerance Value | –40°C to +375°C ±1.5°C 375°C to 750°C ±0.004⋅ |t| | –40°C to +333°C ±2.5°C 333°C to 750°C ±0.0075 ⋅ |t| | N | NICKEL - CHROMIUM -SILICON Also known as: Nicrosil | NICKEL - SILICON - MAGNESIUM Also known as: Nisil | 30 | 38 | 39 | 0 to +1150ºC | -270 to +1300ºC | Temperature Range Tolerance Value Temperature Range Tolerance Value | –40°C to +375°C ±1.5°C 375°C to 1000°C ±0.004⋅ |t| | –40°C to +333°C ±2.5°C 333°C to 1200°C ±0.0075⋅ |t| | E | NICKEL - CHROMIUM Also known as: Chromel™, Tophel™, Chromium, Nickel | NICKEL - Aluminum Also known as: Nickel-Copper, Constantan, Advance™, Cupron™ | 68 | 81 | – | 0 to +800ºC | -40 to +900ºC | Temperature Range Tolerance Value Temperature Range Tolerance Value | –40°C to +375°C ±1.5°C 375°C to 800°C ±0.004⋅ |t| | –40°C to +333°C ±2.5°C 333°C to 900°C ±0.0075 ⋅ |t| | S | PLATINUM - 10% RHODIUM | PLATINUM | 8 | 9 | 11 | 0 to +1550ºC | -50 to +1750ºC | Temperature Range Tolerance Value Temperature Range Tolerance Value | 0°C to +1100°C ±1.0°C 1100°C to 1600°C ±(1 +0.003 (t ⋅ 1100)°C | 0°C to +600°C ±1.5°C 600°C to 1600°C ±0.0025 ⋅ |t| | R | PLATINUM - 13% RHODIUM | PLATINUM | 8 | 10 | 13 | 0 to +1600ºC | -50 to +1700ºC | Temperature Range Tolerance Value Temperature Range Tolerance Value | 0°C to +1100°C ±1.0°C 1100°C to 1600°C ±(1 +0.003 (t ⋅ 1100)°C | 0°C to +600°C ±1.5°C 600°C to 1600°C ±0.0025 ⋅ |t|

Source: <https://www.tc-inc.com/thermocouple/thermocouple-tolerances.html>

R — Thermocouple type letter to alloy pair, ANSI/IEC color code and tolerance class


**Type letter:** R

**Usable temperature range:** –50 to 1768°C

**Source document:** ANSI and IEC Color Codes

> R R Do Not Insert in Metal NONE PLATINUM- Platinum Tubes. Beware of –50 to 1768°C –0.226 – – – 13% RHODIUM Pt Contamination. ESTABLISHED High Temperature –58 to 3214°F to 21.101 Pt-13% Rh

Source: <https://assets.omega.com/pdf/test-and-measurement-equipment/temperature/sensors/thermocouple-probes/tc_colorcodes.pdf>


**Type letter:** R

**IEC 60584-3 positive-leg color:** Orange

**IEC 60584-3 negative-leg color:** White

**IEC 60584-3 outer sheath colour:** Orange

**Source document:** Thermocouple Colour Code Standards

> What is the Colour Code for a Type R Thermocouple? In the UK and Europe, the most widely used colour code for Type R thermocouple cable is to the international IEC 60584-3 standard which is as follows: Positive Leg = Orange, Negative Leg = White, Outer Sheath (Jacket) = Orange, Thermocouple Connector Colour = Orange

Source: <https://www.tc.co.uk/thermocouple-information/thermocouple-colour-code.html>


**Type letter:** R

**Positive-leg alloy:** Platinum 13% rhodium

**Negative-leg alloy:** Pure platinum

**ANSI/ASTM positive-leg color:** Black

**ANSI/ASTM negative-leg color:** Red

**ANSI extension-grade jacket color:** Green

**Source document:** ANSI/ASTM Thermocouple Color Codes

> Type | Positive conductor | Negative conductor | Positive color | Negative color | Extension-grade jacket | Thermocouple-grade jacket shown in legacy assets | T | Copper | Constantan | Blue | Red | Blue | Brown | J | Iron | Constantan | White | Red | Black | Brown | E | Chromel | Constantan | Purple | Red | Purple | Brown | K | Chromel | Alumel | Yellow | Red | Yellow | Brown | N | Nicrosil | Nisil | Orange | Red | Orange | Brown | S | Platinum 10% rhodium | Pure platinum | Black | Red | Green | None established in legacy asset | R | Platinum 13% rhodium | Pure platinum | Black | Red | Green | None established in legacy asset |

Source: <https://thermometricscorp.com/thermocouple-color-codes.html>


**Type letter:** S

**IEC 60584 Class 1 tolerance:** 0°C to +1100°C ±1.0°C 1100°C to 1600°C ±(1 +0.003 (t ⋅ 1100)°C

**IEC 60584 Class 2 tolerance:** 0°C to +600°C ±1.5°C 600°C to 1600°C ±0.0025 ⋅ |t|

**Source document:** Thermocouple Tolerances

> Thermocouple Output Tolerances to IEC 60584-1 | Type | + Leg | - Leg | 100ºC | 500ºC | 1000ºC | Continuous | Short Term | Type | Class 1 | Class 2 | K | NICKEL - CHROMIUM Also known as: Chromel™, Thermokanthal KP*, NiCr, T1*, Tophel™ | NICKEL - Aluminum (magnetic) Also known as: Ni-Al, Alumel™, Thermokanthal KN™, T2™, NiAl™ | 42 | 43 | 39 | 0 to +1100ºC | -180 to +1350ºC | Temperature Range Tolerance Value Temperature Range Tolerance Value | –40°C to +375°C ±1.5°C 375°C to 1000°C ±0.004 ⋅ |t| | –40°C to +333°C ±2.5°C 333°C to 1200°C ±0.0075 ⋅ |t| | T | COPPER | COPPER - NICKEL Also known as: Constantan, Advance™, Cupron™ | 46 | – | – | –185 to +300°C | –250 to +400°C | Temperature Range Tolerance Value Temperature Range Tolerance Value | –40°C to +125°C ±0.5°C 125°C to 350°C ±0.004⋅ |t| | –40°C to +133°C ±1.0°C 133°C to 350°C ±0.0075 ⋅ |t| | J | IRON (magnetic) Also known as: Fe | COPPER - NICKEL Also known as: Nickel-Copper, Constantan, Advance™, Cupron™ | 54 | 56 | 59 | +20 to +700°C | –180 to +750°C | Temperature Range Tolerance Value Temperature Range Tolerance Value | –40°C to +375°C ±1.5°C 375°C to 750°C ±0.004⋅ |t| | –40°C to +333°C ±2.5°C 333°C to 750°C ±0.0075 ⋅ |t| | N | NICKEL - CHROMIUM -SILICON Also known as: Nicrosil | NICKEL - SILICON - MAGNESIUM Also known as: Nisil | 30 | 38 | 39 | 0 to +1150ºC | -270 to +1300ºC | Temperature Range Tolerance Value Temperature Range Tolerance Value | –40°C to +375°C ±1.5°C 375°C to 1000°C ±0.004⋅ |t| | –40°C to +333°C ±2.5°C 333°C to 1200°C ±0.0075⋅ |t| | E | NICKEL - CHROMIUM Also known as: Chromel™, Tophel™, Chromium, Nickel | NICKEL - Aluminum Also known as: Nickel-Copper, Constantan, Advance™, Cupron™ | 68 | 81 | – | 0 to +800ºC | -40 to +900ºC | Temperature Range Tolerance Value Temperature Range Tolerance Value | –40°C to +375°C ±1.5°C 375°C to 800°C ±0.004⋅ |t| | –40°C to +333°C ±2.5°C 333°C to 900°C ±0.0075 ⋅ |t| | S | PLATINUM - 10% RHODIUM | PLATINUM | 8 | 9 | 11 | 0 to +1550ºC | -50 to +1750ºC | Temperature Range Tolerance Value Temperature Range Tolerance Value | 0°C to +1100°C ±1.0°C 1100°C to 1600°C ±(1 +0.003 (t ⋅ 1100)°C | 0°C to +600°C ±1.5°C 600°C to 1600°C ±0.0025 ⋅ |t|

Source: <https://www.tc-inc.com/thermocouple/thermocouple-tolerances.html>

S — Thermocouple type letter to alloy pair, ANSI/IEC color code and tolerance class


**Type letter:** S

**Usable temperature range:** –50 to 1768°C

**Source document:** ANSI and IEC Color Codes

> S S Do Not Insert in Metal NONE PLATINUM- Platinum Tubes. Beware of – 10% RHODIUM –50 to 1768°C –0.236 – – ESTABLISHED Pt Contamination. –58 to 3214°F High Temperature to 18.693 Pt-10% Rh

Source: <https://assets.omega.com/pdf/test-and-measurement-equipment/temperature/sensors/thermocouple-probes/tc_colorcodes.pdf>


**Type letter:** S

**IEC 60584-3 positive-leg color:** Orange

**IEC 60584-3 negative-leg color:** White

**IEC 60584-3 outer sheath colour:** Orange

**Source document:** Thermocouple Colour Code Standards

> What is the Colour Code for a Type S Thermocouple? In the UK and Europe, the most widely used colour code for Type S thermocouple cable is to the international IEC 60584-3 standard which is as follows: Positive Leg = Orange, Negative Leg = White, Outer Sheath (Jacket) = Orange, Thermocouple Connector Colour = Orange

Source: <https://www.tc.co.uk/thermocouple-information/thermocouple-colour-code.html>


**Type letter:** S

**Positive-leg alloy:** Platinum 10% rhodium

**Negative-leg alloy:** Pure platinum

**ANSI/ASTM positive-leg color:** Black

**ANSI/ASTM negative-leg color:** Red

**ANSI extension-grade jacket color:** Green

**Source document:** ANSI/ASTM Thermocouple Color Codes

> Type | Positive conductor | Negative conductor | Positive color | Negative color | Extension-grade jacket | Thermocouple-grade jacket shown in legacy assets | T | Copper | Constantan | Blue | Red | Blue | Brown | J | Iron | Constantan | White | Red | Black | Brown | E | Chromel | Constantan | Purple | Red | Purple | Brown | K | Chromel | Alumel | Yellow | Red | Yellow | Brown | N | Nicrosil | Nisil | Orange | Red | Orange | Brown | S | Platinum 10% rhodium | Pure platinum | Black | Red | Green | None established in legacy asset |

Source: <https://thermometricscorp.com/thermocouple-color-codes.html>


**Type letter:** T

**IEC 60584 Class 1 tolerance:** –40°C to +125°C ±0.5°C 125°C to 350°C ±0.004⋅ |t|

**IEC 60584 Class 2 tolerance:** –40°C to +133°C ±1.0°C 133°C to 350°C ±0.0075 ⋅ |t|

**Source document:** Thermocouple Tolerances

> Thermocouple Output Tolerances to IEC 60584-1 | Type | + Leg | - Leg | 100ºC | 500ºC | 1000ºC | Continuous | Short Term | Type | Class 1 | Class 2 | K | NICKEL - CHROMIUM Also known as: Chromel™, Thermokanthal KP*, NiCr, T1*, Tophel™ | NICKEL - Aluminum (magnetic) Also known as: Ni-Al, Alumel™, Thermokanthal KN™, T2™, NiAl™ | 42 | 43 | 39 | 0 to +1100ºC | -180 to +1350ºC | Temperature Range Tolerance Value Temperature Range Tolerance Value | –40°C to +375°C ±1.5°C 375°C to 1000°C ±0.004 ⋅ |t| | –40°C to +333°C ±2.5°C 333°C to 1200°C ±0.0075 ⋅ |t| | T | COPPER | COPPER - NICKEL Also known as: Constantan, Advance™, Cupron™ | 46 | – | – | –185 to +300°C | –250 to +400°C | Temperature Range Tolerance Value Temperature Range Tolerance Value | –40°C to +125°C ±0.5°C 125°C to 350°C ±0.004⋅ |t| | –40°C to +133°C ±1.0°C 133°C to 350°C ±0.0075 ⋅ |t|

Source: <https://www.tc-inc.com/thermocouple/thermocouple-tolerances.html>

T — Thermocouple type letter to alloy pair, ANSI/IEC color code and tolerance class


**Type letter:** T

**Usable temperature range:** –270 to 400°C

**Source document:** ANSI and IEC Color Codes

> Mild Oxidizing, + + + + T T CONSTANTAN Reducing Vacuum or – – COPPER COPPER- Inert. Good Where –270 to 400°C –6.258 to – – Cu Moisture Is Present. Low NICKEL Temperature & Cryogenic –454 to 752°F 20.872 Cu–Ni Applications

Source: <https://assets.omega.com/pdf/test-and-measurement-equipment/temperature/sensors/thermocouple-probes/tc_colorcodes.pdf>


**Type letter:** T

**IEC 60584-3 positive-leg color:** Brown

**IEC 60584-3 negative-leg color:** White

**IEC 60584-3 outer sheath colour:** Brown

**Source document:** Thermocouple Colour Code Standards

> What is the Colour Code for a Type T Thermocouple? In the UK and Europe, the most widely used colour code for Type T thermocouple cable is to the international IEC 60584-3 standard which is as follows: Positive Leg = Brown, Negative Leg = White, Outer Sheath (Jacket) = Brown, Thermocouple Connector Colour = Brown

Source: <https://www.tc.co.uk/thermocouple-information/thermocouple-colour-code.html>


**Type letter:** T

**Positive-leg alloy:** Copper

**Negative-leg alloy:** Constantan

**ANSI/ASTM positive-leg color:** Blue

**ANSI/ASTM negative-leg color:** Red

**ANSI extension-grade jacket color:** Blue

**Source document:** ANSI/ASTM Thermocouple Color Codes

> Type | Positive conductor | Negative conductor | Positive color | Negative color | Extension-grade jacket | Thermocouple-grade jacket shown in legacy assets | T | Copper | Constantan | Blue | Red | Blue | Brown |

Source: <https://thermometricscorp.com/thermocouple-color-codes.html>


**Type letter:** U

**Source document:** ANSI and IEC Color Codes

> Extension Grade + + + U U NONE COPPER-LOW Connecting Wire for ESTABLISHED – COPPER R & S Thermocouples, – – Cu NICKEL Also Known as RX & SX Cu-Ni Extension Wire.

Source: <https://assets.omega.com/pdf/test-and-measurement-equipment/temperature/sensors/thermocouple-probes/tc_colorcodes.pdf>

U — Thermocouple type letter to alloy pair, ANSI/IEC color code and tolerance class