Fe-CuNi thermocouple (type J) is also named Fe- Constantan thermocouple. The positive leg Fe(JP) is made by pure Iron, and the main chemical composition of negative leg Constantan (JN) is Cu: Ni≈ 55%: 45%. Although they are all called Constantan, JN does not give the same EMF output curve as EN and TN, it cannot be instead by other Constantan.

Cu-CuNi thermocouple (type T) is also named Cu- Constantan thermocouple. The positive leg Cu(TP) is made by pure Copper, and the main chemical composition of negative leg Constantan (TN) is Cu: Ni≈ 55%: 45%. Although EN, TN, JN are all called Constantan, TN and EN don not give the same EMF output curve as JN. EN and TN are able to interchange but they are not interchangeable with JN. The operating temperature range of type T thermocouple is -200~350℃, Due to the low resistance of oxidation that Copper has, it is not advisable to go beyond that range.

Nicrsi-NisiMg (Type N) thermocouple is the latest base metal thermocouple, developed to improve the drawbacks that type K thermocouple has. The main chemical composition of positive leg Nicrsi (NP) is Ni: Cr: Si≈84.4: 14.2: 1.4; negative leg NisiMg (NN) is Ni: Si: Mg≈95.5: 4.4: 0.1. Type N thermocouple also be used in the similar atmospheres that type K works, and the operating temperature range is -200~1300℃.

NiCr-NiSi (Type K) thermocouple finds the widest use in all base metal thermocouple, at temperature above 500℃。The main chemical composition of  positive leg NiCr (KP) are Ni≈90% and Cr≈10%; negative leg NiSi (KN) are Ni≈97% and Cr≈3%. The operating temperature range is -200~1300℃(for short term) and 0~1100℃( for long term)

NiCr- CuNi thermocouple (type E) is also named NiCr- Constantan thermocouple. The main chemical composition of positive leg NiCr (EP) is Ni: Cr≈90:10; negative leg Constantan (EN) is Cu: Ni≈ 55%: 45%. Although EN, TN, JN are all called Constantan, EN and TN don not give the same EMF output curve as JN. EN and TN are able to interchange but they are not interchangeable with JN. The operating temperature range of type E thermocouple is -200~900℃.