Ungrounded vs. grounded thermocouples

This article will explain the difference between ungrounded and grounded thermocouples.

Thermocouples are also known as "probes". 

Thermocouples are made of two different metals in the form of wires that are welded together to form a junction. The junction is protected by a metal hull.

It is not possible to determine whether the thermocouple is grounded or ungrounded just by looking at it.

You will need a multimeter to perform this test as shown in this video by Omega.

Source: https://www.omega.com/en-us/resources/selecting-a-thermocouple

Ungrounded thermocouples

When a thermocouple is ungrounded, the junction is detached from the sensor hull and electrically isolated.

The detached junction results in slower response times compared to grounded probes. The electrically isolated junction prevents the signal from being interrupted by electrical noise. Thus the accuracy of the temperature measurement is much higher. 

At Cropster, we recommend ungrounded probes to measure your temperatures

Screenshot 2024-07-04 at 11.38.36

Pros Cons
  • Better resistance to electrical noise and ground loops. 
  • Higher accuracy.


  • Slow response times.

Grounded thermocouples

When a thermocouple is grounded, the junction is welded directly to the inside of the hull at the tip of the sensor which results in an effective heat transfer thus faster response times.

However, grounded thermocouples are prone to induce noise from ground loops which results in a less accurate reading. 

These types of probes are recommended to measure the temperature of gases and liquids.

Screenshot 2024-07-04 at 11.40.48

Pros Cons
  • Fast response times.
  • Noise-inducing.
  • Less accurate reading.

Congratulations! You have learned what's the difference between the ungrounded and grounded thermocouples. 

Your opinion matters. If you have further questions, feedback, or concerns, please feel free to reach out by submitting a support ticket directly from support.cropster.com