IEC and ANSI colour codes are not interchangeable; verify the instrument.
| Type | IEC 60584-3 | ANSI MC96.1 | DIN 43714 | JIS C 1602 | BS 1843 |
|---|---|---|---|---|---|
| K | Green / White | Yellow / Red | Red / Green | Red / White (blue sheath) | Red / Brown |
| N | Pink / White | Orange / Red | Red / Grey | — | Orange / White |
| J | Black / White | White / Red | Blue / Red | Yellow / White (yellow sheath) | Black / Blue |
| T | Brown / White | Blue / Red | Brown / Red | Brown / White (brown sheath) | White / Blue |
| E | Purple / White | Purple / Red | Black / Red | Purple / White (purple sheath) | Brown / White |
Wiring check
- Read the standard the instrument expects — not the one printed on the cable being replaced.
- Match the conductor colour to that standard before terminating anything.
- On bare wire with no insulation, confirm polarity with a magnet: Alumel is magnetic, Chromel is not.
- Where the two ends of a run were supplied to different standards, re-terminate rather than adapt.
Important notes
The colour code applies to the insulation of each individual conductor and the outer sheath of the cable. For bare wire without insulation, there is no colour code — the positive and negative legs are distinguished by their magnetic properties (Alumel is magnetic, Chromel is not) or by surface appearance.
IEC and ANSI colour codes are not interchangeable. A Type K thermocouple wired to ANSI colours will read incorrectly if connected to an IEC-configured instrument. Always verify the standard your instrument expects before connecting.
For extension and compensating cable, the outer sheath colour follows the same standard as the positive conductor.
Frequently Asked Questions
Are IEC and ANSI thermocouple colour codes interchangeable?
No. A Type K thermocouple wired to ANSI colours will read incorrectly when connected to an IEC-configured instrument, and vice versa. Always verify which standard the instrument expects before terminating.
How do I identify the polarity of bare wire with no insulation?
Use magnetic properties: Alumel is magnetic while Chromel is not, so a magnet identifies the negative leg on Type K. Surface appearance is a weaker secondary check.
What is the colour code of Type K under IEC 60584-3?
Green for the positive leg and white for the negative leg. Under ANSI MC96.1 the same Type K pair is yellow and red — which is exactly why the two systems must not be mixed.
Does the outer sheath colour follow the conductors?
For extension and compensating cable, yes: the outer sheath colour follows the same standard as the positive conductor.
Bottom line: Colour codes are a wiring convention, not a property of the alloy — the same Type K pair is green/white under IEC 60584-3 and yellow/red under ANSI MC96.1. Read the code off the instrument rather than off the old cable, and check polarity on bare wire with a magnet.