Steel or PVC?

[Tinyotall]

Need to first fix a porch, does it matter which capping I use? PVC or Steel?

 

[redrocket10000]

I reckon the only purpose of plastic capping, is to prevent cement products covering cables from breaking down the cable insulating material, i've found this to be true when the wall containing the cable is continuously damp and thus the lime in cement product reacts with the moisture and becomes acidic. Apart from that i can see no reason to use plastic. Imo