TECHNICAL GUIDES: ANSI Thermocouple Color Code Chart
Use this chart to identify thermocouple type, polarity and the matching plug or jack by color. It covers the ANSI color code used in North America for Types J, K, T, E, N, R, S and B. If a thermocouple reads backward or reads the wrong temperature, wrong polarity or a wrong plug type is the first thing to check.
Plugs, jacks and wire from Wilcon
Wilcon stocks color-coded ANSI plugs and jacks and builds thermocouples to your length, diameter and termination.
- Type K standard plugs
- Type K mini plugs
- Type K standard jacks
- Standard Type K MGO thermocouples
- Standard Type J MGO thermocouples
Need a plug or wire for a different type, or a cable that mixes ANSI and IEC? Send us the type and what you are connecting to and we will confirm the right part.
Frequently asked questions
Yellow. The positive leg is yellow, the negative leg is red, and the plug and extension wire jacket are yellow under the ANSI code.
The ANSI color code uses red for the negative leg on every thermocouple type, so you can find polarity without knowing the alloy. IEC cables use white for the negative leg.
The instrument reads the temperature change in the wrong direction. It may show a falling reading as the process heats up, or a value that is far from the real temperature. Swap the legs back at the plug, jack or terminal.
No. The plug contacts are made of the matching alloys. A wrong-type plug adds a junction of different metals and gives a false reading.
Thermocouple-grade wire in the ANSI code has a brown jacket. Color-coded jackets are used on extension wire. Read the printed type on the jacket.
Colors and ranges follow ANSI MC96.1 and ASTM E230 conventions. Standards are revised from time to time. Confirm against the current standard and your cable or instrument markings before wiring critical equipment.