Safety Tip – Ground Potential Rise (GPR) or Step & Touch Voltages and Transients

Not all that long ago if you were really paying attention, you could see beer bottles lined up atop transmission towers. Some of you “old timers” know exactly how they got there – wink. Fortunately the Utility Crew Safety Culture has come a long way since those days.

The increased hazards you face on the job site, driven by greater power volume and speeds, tighter corridors, bleepin’ copper thieves and challenges like this inspired me to start this blog as a place where that constantly improving Safety Culture can be highlighted and talked about. In fact, I am going to start out with a series of Safety Tips, but let me know what else you are interested in. We’ll involve Safety Managers, IEEE Panel Members, Trainers and anyone else we need to get solid data.

Safety Tip – Ground Potential Rise (GPR) or Step & Touch Voltages and Transients
Avail yourself of the best tools available on the market.

Electrical engineers call it, “Ground Potential Rise” (GPR). Some say “Earth Potential Rise” (EPR). I’ve heard “Step & Touch”, “step voltage”, “touch voltage”, and “transfer touch voltage” and a variety of names I won’t repeat, but no matter what it is called, when it’s on your worksite… you had better be aware “its” there and at what level. Ground Potential Rise is a frequently misunderstood site-safety issue in the distribution of power and telecommunications services. I have talked with crews who just thought they were “getting bit” by rogue static electricity, so did not take necessary precautions. Once they could see it measured in real time by our GroundHound Site Safety Monitoring System, they “got religion” real fast!

Gary Zevenbergen, Electrical Engineer, Trainer and Inventor – Western Area Power Administration
Linemen, working on de-energized high-voltage transmission lines, can be exposed to electric shock hazards. Proper use of clearance procedures, as outlined in OSHA 1910.269(m), and a properly installed work site grounding system are utilized to mitigate these shock hazards. However, not all shock hazards can be removed from the work site. Shock Hazards associated with ground potential rise, namely step voltage, touch voltage, and transfer touch voltage, will exist anytime current is injected into the earth through the work site grounding system.

Transients or GPR spikes on job sites or at substations can vary wildly and causes exposure to extremely hazardous voltages. They can be so high as to be lethal. Worst of all, they can be caused by simple things such as switching events. When they happen you want to know about it. You want to know how high that voltage spike was and have a record of it so that you can talk with dispatch and ask them to let you know first if they plan to do something you are seeing causes transients. The data logging helps support your ability to work out procedural changes as necessary. We have tested for and seen lethal transients happen as far as 60 miles away from the event that caused it.

Additionally, you want an instrument that not only monitors, alarms and logs that data, but one that has the ability to show you what you need to know without compelling you to walking across that dangerous ground to look at its readout! That just doesn’t make sense! Of course you wouldn’t do that. We introduced an instrument that can be controlled and read from a safe distance, using a smart phone.

So, this is my first safety tip: The conditions on the ground have not always been there so this means it’s a whole new world where safety is evolving. Avail yourself of the best safety instrumentation available in the market today and make sure it is truly designed for the environment it is supposed to operate in. You need a warning system that alarms for different levels of danger so that you know when additional protective gear or a site shut down is appropriate. In the case of Step & Touch, you need an instrument that accurately monitors in real-time and records the data for use or analysis and one that allows you to keep a safe distance by providing you with remote reporting.

Regardless of what instrument or method you choose, it is crucial to warn the high voltage worker when the work site GPR rises that are not safe or require additional protection protective gear.

I’m looking forward to posting more Safety Tips from the experts again soon! Jody Singleton

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