Over the past six months, three things have happened that I want to mention. First, I have answered numerous questions from clients and Incident Prevention readers regarding personal protective grounding (PPG). Second, the industry has experienced a rash of injuries and fatalities related to current in grounded circuits. The incidents most often have been associated with induction, but not always. And third, I have consulted with utilities and contractors, large and small, who are just now recognizing they have issues understanding PPG. It’s been hard to gauge the numbers – such as the frequency of incidents and especially comparing the seriousness of injuries – because there is no reliable clearinghouse for tracking incidents other than fatalities reported to the U.S. Department of Labor.
All of this is beside the real point, however, which is that there is no reason for any of these incidents to have occurred at all. Well, there is one: The utility industry is behind the curve in their understanding of the phenomenon of current in grounded conductors. There is an explanation for that, and it’s time to write about it again.
Let me be clear: The purpose of this article is to work toward solving the problem, not to find fault. To understand how we got to where we are, let’s first talk about industry awareness. Anyone who does research on the fundamentals of utility system grounding will notice that we have been struggling with PPG since as early as the 1950s. This has been documented in various papers from the IEEE archives of “Proceedings of the IEEE” – one of the first electrical industry journals, established around 1927 – and in “IEEE Transactions on Power Systems” since 1985.
As the IEEE 1048 standard, “IEEE Guide for Protective Grounding of Power Lines,” points out in the introduction to the 2003 edition, “Protective grounding methods have often not kept pace with their increasing importance in work safety as the available fault current magnitudes grow, sometimes to as high as 100 kA, and as right-of-ways become more crowded with heavily loaded circuits, leading to growing problems of electric or magnetic induction.” Did you notice the date of the standard? The 2003 edition is a revision of the 1990 standard on protective grounding. As I stated earlier, we’ve been struggling with PPG since as early as the 1950s. Over 60 years is a long time to still not have figured it out.