Case Studies – Copper Bonded Steel Grounding Systems in Australia and USA
Copper-bonded steel ground rods, that meet UL, BS and IEC requirements, have been used in ground electrode systems in the telecommunications and electrical industry for many decades. In copper-based grounding systems, horizontal conductors that interconnect these ground rods, have been either pure copper or tinned copper conductors. Due to the cost pressures in telecommunications rollouts, reoccurrence of copper theft, multiple industry players in the Australian and the United States of America, the customer turned to nVent ERICO to come up with a more cost effective horizontal conductor, without compromising corrosion or electrical performance. This seemed a difficult exercise at first as legacy copper conductors are well proven conductors, which provide high conductivity and corrosion resistance across a wide range of environments. However, with careful development of new conductors that compose of more than one metal, suitable solutions have been developed. Furthermore, testing guidelines for these alternative materials have been developed. In this paper, we will look at two case studies where alternative materials have been successfully implemented. We will explain key attributes of the conductor to be considered and suggest suitable methods to test these attributes.
Case Study 1 This first case study looks at the field implementation of horizontal copper-bonded steel conductors, Cu-Bond Round Conductor (CBSC, 8-10 mm diameter) as part of the radio site grounding system in Australia. We will look at the challenges initially faced and methods used in the field to overcome these challenges and turn them into significant advantages. This involved using long straightened lengths of the CBSC as opposed to coiled lengths. The rigidity of the conductor allowed connections to be done out of the trench and dropped in. The installers found it easier to install the CBSC compared to ductile conductors which sag in trenches. Installers noted significant time savings when compared to more ductile conductors.
Study 2 Telecommunications carriers in the U.S. face copper theft as a significant problem in their cellular networks. Most of the theft happens above ground with copper ground bars and copper wires connecting above and below grounding systems. The copper theft happens either during construction stages or later on when the sites are operational. If the theft occurs during construction, then there is economic loss and an annoyance. However, theft of copper in operational facilities is a larger concern because it brings about a serious safety problem, not only for the equipment, but for the copper thieves and the general public. When the connection to the ground grid is removed, there is serious impact on the ability to protect against power system faults, lightning impulses and noise level at a telecommunications site. To overcome this perennial problem Cu-Bond Stranded Conductor has been used. This is a bare concentric stranded conductor that consists of peripheral tinned copper plated steel which protects and conceals the internal tinned copper stranding.