C
For C, positive-leg alloy is Tungsten 5% rhenium; negative-leg alloy is Tungsten 26% rhenium; ansi/astm positive-leg color is Green; ansi/astm negative-leg color is Red; ansi extension-grade jacket color is Red, verified against its source on 2026-08-19.
- Type letter
- C verified
- Positive-leg alloy
- Tungsten 5% rhenium verified
- Negative-leg alloy
- Tungsten 26% rhenium verified
- ANSI/ASTM positive-leg color
- Green verified
- ANSI/ASTM negative-leg color
- Red verified
- ANSI extension-grade jacket color
- Red verified
- Source document
- ANSI/ASTM Thermocouple Color Codes verified
- Usable temperature range
- 0 to 2320°C per assets.omega.com
- IEC 60584-3 positive-leg color
- Red per tc.co.uk
- IEC 60584-3 negative-leg color
- White per tc.co.uk
- IEC 60584-3 outer sheath colour
- Red per tc.co.uk
What the source says
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 |
— thermometricscorp.com, retrieved 2026-08-19
Sources disagree
More than one authority states this, and they do not state the same thing. Both are reproduced with the source each came from — deciding between them is yours, not ours.
Source document
thermometricscorp.com says source document is ANSI/ASTM Thermocouple Color Codes, as of 2026-08-19.
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 |
https://thermometricscorp.com/thermocouple-color-codes.html
assets.omega.com says source document is ANSI and IEC Color Codes, as of 2026-08-19.
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)
tc.co.uk says source document is Thermocouple Colour Code Standards, as of 2026-08-19.
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
https://www.tc.co.uk/thermocouple-information/thermocouple-colour-code.html
Sources
- thermometricscorp.comhttps://thermometricscorp.com/thermocouple-color-codes.html
- assets.omega.comhttps://assets.omega.com/pdf/test-and-measurement-equipment/temperature/sensors/thermocouple-probes/tc_colorcodes.pdf
- tc.co.ukhttps://www.tc.co.uk/thermocouple-information/thermocouple-colour-code.html