Grounding And Lightning Protection - Honeywell STT700 STT700 User Manual

3.4.4. Grounding and Lightning Protection

Connect a wire from the mounting screws to Earth Ground to make the protection effective. Use size
2
14 AWG or 2.0mm bare or green covered wire for this connection.
For ungrounded thermocouple, mV, RTD or ohm inputs, connect the input wiring shield(s) to the
same Earth Ground connection.
For grounded thermocouple inputs, connect the internal ground connection shown in Figure 11 to the
same Earth Ground as used by the thermocouple. For direct head mount housings, the ground
terminal may not exist and another means of direct ground connection will need to be devised. For
proper protection, the green ground wire must be securely connected to a local ground in as direct a
path as possible. As noted above, the loop power wiring shield should only be connected to Earth
Ground at the power supply end.
The tightening torque to be applied on the wire termination screws are to be
between 0.34 Nm (3 in-lbf) min to 0.56 Nm (5 in-lbf) max.
Shielded twisted pair cable gauge 18AWG-22AWG for the sensor connections and
22AWG – 14AWG for the loop power connections.
The tightening torque to be applied on the STT700 module mounting screws are to be
between 1.0 Nm (8.85 in-lbf) min to 1.35 Nm (12 in-lbf) max.
Revision 1
STT700 Temperature Transmitter User's Manual
Page 19