If a device such as this potentiometer has a metal case, should the case be grounded or left floating? Electrically the case is not connected. Data sheet
Electronic – If a device has a metal case should it be grounded
casesground
Related Solutions
Omega's guide is focusing more on the thermocouple itself. Analog Devices' article focuses more on the sugnal conditioning for thermocouples. I'll explain what is implied by Grounded and Ungrounded in the Omega's guide. In the context of the Omega's guide, the thermocouples are a part of thermocouple assemblies or thermocouple probes.
Ungrounded thermocouple. Thermocouple wires are not connected to the sheath of the thermocouple probe.
Grounded thermocouple. Thermocouple is deliberately connected to the sheath to improve the response time.
Here's an example of how a thermocouple probe can be used. It measures temperature of water in a tank. The tank and water are grounded. As a result, the sheath of the probe is grounded. If the thermocouple itself is connected to the probe sheath, then the thermocouple is grounded to the tank, no matter how you connect the thermocouple wires. If thermocouple wires are not connected to the sheath, you can connect the output ends as you see fit.
It's a common problem any time you get a high power output signal anywhere near the instrument level input signal. It's an induction/radiation problem, and it basically causes feedback. Always keep your instrument and its cabling away from your speaker wiring.
Best Answer
Floating pieces of metal are mostly unwanted. The reason is that they have an high impedance to the environment and can pick up noise and then induce noise to you circuit.
By connecting it to your ground plane the noise will flow a defined path to your ground instead of some sensitive circuit nearby.
BUT: Be aware that these components usually stick out of your enclosure. An esd discharge path is also created to your ground. If you have a metal enclosure connect it directly to the enclosure and prevent the discharge going via your pcb. If esd is a high risk and you have a plastic enclosure, make sure you add proper esd suppression. Isolating this piece of metal by not connecting it to anything is almost impossible because of the pins nearby (small spark gap).