A Guide to Thermocouple Wire

A thermocouple is a device used for measuring temperature, which consists of two different conductors that are attached only at the end. It produces a small voltage everytime the ends sense different temperatures which is equivalent to temperature changes between the ends. Thermocouple wire or thermocouple extension wire is used to connect thermocouples to sense or control instrumentation.


It all started back in 1822 when a physician named Thomas Seebeck accidentally discovered that the connection between two metals produces a voltage which is a function of temperature. From then on, this phenomenon is called as the Seebeck effect. Thermocouples rely on this effect and although most types of metals can be used for making thermocouples, not all them belonged to the standard types used. Those standard types of Thermocouple wire are used for the purpose of coming out with consistent output voltages and large temperature gradients.



  • Because of its versatility, thermocouples are most preferred to be used in measuring temperatures. They are rugged, can withstand shock and vibration, and can measure over wide ranges of temperature.
  • Thermocouples are widely used on experiments because of its strength and ability to measure wide ranges, and peculiar characteristics.
  • On the other hand, a thermocouple produces a non-linear low output signal through its thermocouple wire. When this happens, one will need a more stable and sensitive device that has the ability to provide linearization as well as reference junction compensation.
  • Thermocouples must posses a good noise rejection capability in order for it to avoid ground loop problems when the common mode range and rejection are inadequate.



Type J Thermocouple: This consists of iron and constantan metals, and is commonly used in inert, oxidizing, vacuum, or reducing atmospheres. As compared to constantan, the iron element in this types of thermocouple wire oxidizes faster at temperatures higher than 1000 degrees Fahrenheit.

Type K Thermocouple – Consisting of chromel and alumel alloys, it is also used in inert, oxidizing, and reducing temperatures. K thermocouple wire is by far the most popular type of thermocouple, and known to be accurate and reliable at high temperatures.

Type T Thermocouple: This thermocouple contains copper and constantan and just like others, it is alo used in oxidizing, inert, dry reducing atmospheres as well as in vacuum. This type of thermocouple wire has high resistance against corrosion that results from atmospheric moisture and is highly stable during low temperatures.

Type N Thermocouple: With alloys nicrosil and nisil, it is produces accurate and reliable results in reducing temperatures, oxidizing, and inert during high temperatures.

Type E Thermocouple- This is the thermocouple that has a combination of chromel and constantan and is often used in inert, oxidizing, and dry reducing temperatures. To protect this thermocouple wire, it should be out of contact with sulfurous and oxidizing atmospheres.


These are the leading thermocouple wire manufacturers in the market today:

  1. Alpha Wire and Company: Thermocouple wire and Cable
  2. Belden: Non-Paired Thermocouple wire and Thermocouple Extension Wire
  3. MultiCable Corporation: Thermocouple wire and Cable
  4. Omega: E, K, J, N, T Types of Thermocouple wire Manufacturer, Kapton and TFE Insulated
  5. Watlow: Thermocouple wire and Cable