I was recently asked to provide information about the challenges and opportunities found when working on direct-buried underground distribution (UD) systems. In light of that request, I’ll address those topics in this installment of “Voice of Experience.”
My first opportunity to work on UD systems was as a truck driver operating a trencher in the late 1960s. UD systems were fairly new at the time; lineworkers were learning new techniques, using different types of tools to terminate cables and installing switchable elbows. In that day, some elbows were non-load-break. Back then the work was all about proper use of tools, identifying equipment and following the minimum rules. There were no OSHA regulations. We learned many techniques and work practices the old-fashioned way: through the school of hard knocks.
The challenges that workers faced back then are much the same as they are today, with two exceptions: The industry has more experience installing and operating UD systems, and equipment is now much more technically sophisticated and reliable. For many years, maintenance of UD systems was nonexistent. The common approach was to dig a ditch and put cable in the ground, and industry workers believed everything would last forever. That belief was short-lived; within a few years, external concentric neutrals began oxidizing, and radial and loop-fed systems suddenly became single-conductor, earthen-ground return systems. Driven ground rods at transformers split coil for secondary voltages. There was no neutral conductor for return currents or fault current flow.