ABSTRACT
With the advent of the underground residential distribution (URD) systems in the early 1960s, the emphasis on reducing the costs of those systems led to finding ways to reduce installation costs. One factor was the elimination of jackets for most of the primary cable installed in the United States. The justification for eliminating the overall jacket could be found in the trade journals of the day:
o Better grounding when the copper concentric "neutrals" were placed directly in the ground with bare or coated tin or lead alloy wires.
