Drain Wire Connection

Hi,

You should connect the Drain Wire from Multicore cable from Marshalling Cabinet in Junction Box to a common bar to which all the drain/shield cables from transmitter cables will be connected. The transmitter cable shield/drain wire should be cut or isolated at Transmitter housing. Make sure that these drain wires/shield are connected to ONE END ONLY - preferable to Marshalling Cabinet side where from it will to a SOLID ground. The common Bar - a copper bar with multiple screws on it can be installed in JB, which can be used for multiple drain wire connections comming from all other field instruments.

Regards,

Thank you for the information. You mean to say that to connect the individual drain wire from all field instruments and the drain wire of the respective multipair cabel to connect to the common bar inside the junction box, and to connect the other end of multipair cable drain wire to the safety ground at the control panel end.

Am I wright?

Yes thats right..... But then make sure that the drain wire of transmitter cable, at transmitter end, is NOT connected to anywhere. You may cut the DRAIN wire and insulate properly, in the transmitter housing.

Thank you for the reply. Can we use this type of grounding of drain wire for digital cable too.?

This is only a protective earth hence it can be connected to protective earth line not to signal earth. Both the earths are ultimately connected to Electronic earth, not to station earth.

No double earthing is allowed for instrument cables if you use panel protective earthing the drain wire should not be connected to marshalling earth also. If marshaling earth is connected to electronic earth then it can be used but connection at the panel should be disconnected only one earthis allowed. It is same for both analog and digital cable.

Follow the Cabling Standards in use at the installation.