Most nations fostered their own thermocouple wire variety codes quite a while back. Today, there are two administering bodies that are around the world perceived for setting the acknowledged variety codes guidelines: ASTM International (previously known as American Society for Testing and Materials or ASTM) and International Electrotechnical Commission (IEC). ASTM E230-03 is the standard taken on by the United States. The standard perceived in Europe is IEC 584-3.

The table gave beneath characterizes the thermocouple alignment types in the left segment (i.e., Type J, K, E, T, N, S) and the compound mix for the positive (+) and negative (- ) leads. The standard protection tones for the different thermocouple leads are represented in the leftover sections beneath the country.

Significant: The variety outline addresses the principles for thermocouple augmentation exactness wire. For standard breaking point and extraordinary cutoff precision thermocouple wire, ASTM gets down on an alternate coat tone - brown.