9. Should I use a grounded or ungrounded thermocouple?

A thermocouple is called “grounded” when the sensing junction is connected (physically and electrically) to the metal case. There are advantages and disadvantages but generally ungrounded thermocouples are preferable, providing a slower response time is acceptable. 

Thermocouple Advantages Disadvantages
Grounded Provides intimate contact for a faster response time Grounded tip construction is susceptible to induced noise from ground loops, resulting in a less accurate reading
Ungrounded
Provides a more accurate reading Slower response time

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