Wrapping power cords and interconnects with copper foil.

@mitch2 said:

Are you assuming the shield is acting as the ground?

Not assuming, Stating a fact... IF it is connected at both ends with the EGC, (Equipment Grounding Conductor). (Therein male plug end and IEC connector end.)  It becomes a parallel EGC.

If a closed ground fault circuit is provided current will travel in the EGC as well as the parallel connected shield. Current does not discriminate. It will take any path that is provided back to the source. In this case the Utility Power transformer.

If you DIY your own shielded power cords only connect the shield to the EGC at the male plug end. Leave the other end of the shield, at the IEC connector, floating.

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@jea48 

”If you DIY your own shielded power cords only connect the shield to the EGC at the male plug end. Leave the other end of the shield, at the IEC connector, floating.”

That is actually how I have always done it. I have never constructed a cable, including interconnects, where the shield acted as the ground, although I have seen it done with some manufactured interconnects when configured as balanced cables.  My practice has been to always use a separate ground wire (same size as the connector wires) attached at both ends but to attach the shield only at the source end.  That has worked well for me.

@mitch2 

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A good example where a shield is also used as a signal ground is a Coax Cable.