Cable screens connected to circuit ground?

[eem2am]

Hi,
We have a system in a plastic enclosure comprising multiple PCBs interconnected by cables and looms. One PCB comprises the 4 SMPS's. There is an offline 20W SMPS on this PCB also. Our circuit ground is directly connected to earth. We need cable screens for all the cables. Do you agree that we must connect our cable screens to circuit ground at each end of the cable? The thing is, do you also agree that we need to put ferrite beads in the connection leading to the cable screen, in every case?
You see, the situation is that we do not have a separate chassis ground, because our enclosure is plastic...so therefore we cannot connect our cable screens to any chassis ground.

 

[Bluejets]

Any screening is normally done one end only to avoid earth loop current flow and again, usually at the source end.