I ran across a weird old MV cable that had a copper shielding tape (grounded) and above it, a metal (appeared to be iron because my magnet worked with it) tape. Why are MV cables shielded with Copper? Can a cost effective iron or iron-based alloy shield do the trick (I am sure flexibility comes into question)?

 

I ran across a weird old MV cable that had a copper shielding tape (grounded) and above it, a metal (appeared to be iron because my magnet worked with it) tape. Why are MV cables shielded with Copper? Can a cost effective iron or iron-based alloy shield do the trick (I am sure flexibility comes into question)?

https://www.ecmweb.com/content/article/20890741/focus-on-the-fundamentals-of-shielded-mv-power-cable

A metallic shield can be configured as either concentric copper wire applied helically and closely spaced, spiral-wrapped copper metal tape with an overlap, or corrugated copper wires embodied in a semi-conducting jacket (available in one make of MV power cable). Each has its own advantages and disadvantages. A concentric wire shielded cable is more flexible and has a tighter minimum bending radius; however, the cable is more likely to suffer damage during installation if allowable pulling tensions and/or sidewall pressures are exceeded. A tape shield covers 100% of the insulation, resulting in greater physical protection for the cable. It also has a higher short-circuit capacity, which can be adjusted in the design stage to allow for even larger currents. The embedded corrugated wire metallic shield also has a high short-circuit capacity and is used to strip the jacket away from the insulation. As to shielding effectiveness, all work equally well. In fact, each possesses features that make it the best choice under certain conditions.