Thermocouple Wire Color Codes

Thermocouple (T/C) lead wires consist of two individual wires (positive and negative), enclosed by coloured insulation sheath:

Thermocouple Wire Insulation Colour Coding

Due to the Seebeck effect, thermocouple wires have a set polarity such that positive and negative wires must be connected to the correct terminals. A variety of standards exist for lead wire insulation colours to identify each thermocouple type.The different standards utilize unique wire colours to differentiate
between the positive and negative leads. 

In North America it is typical that the negative lead is red in accordance with   ASTM E230. However, the most widely used global standard for thermocouple wires is IEC 60584 where the negative lead is typically white.

When applying thermocouples, the standard to which the device is manufactured must be known so that the correct colour code is followed. There are other standards used in various countries: BS1843 - United Kingdom and Czech Republic); DIN43710 -  (Germany), JIS-C1610 (Japan);NFC 42-324 -  (France)
The varrious colour codes and international standards as applied to thermocouple wire insulation colour coding is tabulated below:

T/C type	North America ASTM E230			International IEC 60584	BS 1843 (UK)	DIN 43710 (Germany)	JIS C1610 (Japan)	NFC  42-324 (France)
	Thermocouple Grade		Extension Grade
B	Negative Conductor	N/A	Red	White	N/A	Grey	Grey	N/A
	Positive Conductor	N/A	Grey	Grey	N/A	Red	Red	N/A
	Sheath	N/A	Grey	Grey	N/A	Grey	Grey	N/A
E	Negative Conductor	Red	Red	White	Blue	Black	White	Purple
	Positive Conductor	Purple	Purple	Purple	Brown	Red	Red	Yellow
	Sheath	Brown	Purple	Purple	Brown	Black	Purple	Purple
J	Negative Conductor	Red	Red	White	Blue	Blue	White	Black
	Positive Conductor	White	White	Black	Yellow	Red	Red	Yellow
	Sheath	Brown	Black	Black	Black	Blue	Yellow	Black
K	Negative Conductor	Red	Red	White	Blue	Green	White	Purple
	Positive Conductor	Yellow	Yellow	Green	Brown	Red	Red	Yellow
	Sheath	Brown	Yellow	Green	Red	Green	Blue	Yellow
N	Negative Conductor	Red	Red	White	Blue	N/A	N/A	N/A
	Positive Conductor	Orange	Orange	Pink	Orange	N/A	N/A	N/A
	Sheath	Brown	Orange	Pink	Orange	N/A	N/A	N/A
R	Negative Conductor	N/A	Red	White	Blue	White	White	Green
	Positive Conductor	N/A	Black	Orange	White	Red	Red	Yellow
	Sheath	N/A	Green	Orange	Green	White	Black	Green
S	Negative Conductor	N/A	Red	White	Blue	White	White	Green
	Positive Conductor	N/A	Black	Orange	White	Red	Red	Yellow
	Sheath	N/A	Green	Orange	Green	White	Black	Green
T	Negative Conductor	Red	Red	White	Blue	Brown	White	Blue
	Positive Conductor	Blue	Blue	Brown	White	Red	Red	Yellow
	Sheath	Brown	Blue	Brown	Blue	Brown	Brown	Blue