Spectrum Controls 1756sc-IF8u - Manual (Page 111)

Appendix B: Using Grounded Junction, Ungrounded Junction, and Exposed Junction Thermocouples
99
For grounded junction thermocouples it is recommended that they have
protective sheathes made of electrically insulated material (e.g. ceramic),
or the metal protective sheaths be floated. The metal sheaths would need
to be floated with respect to any path to chassis ground or to another
thermocouple metal sheath. This means the metal sheath must be
insulated from electrically conductive process material, and have all
connections to chassis ground broken. It should be noted that a floated
sheath may result in a less noise immune thermocouple signal.
+
-
CH3
+
-
CH0
MUXES
1756sc-IF8u
Grounded junction with shielded cable
Metal sheath with electrical
continuity to thermocouple
signal wires.