The American Lineman: Improving Safety for Linemen

The Evolution of Personal Protective Grounding Part 1

Alan Drew, Author of The American Lineman, Retired SVP of Research & Development at NLC

This article is intended to cover some of the key improvements in personal protective grounding that have occurred over the years. Today’s linemen must work on de-energized lines for many of the same reasons as the pioneers—repair storm damage, upgrade existing lines, install new lines adjacent to energized lines, etc. Effective personal protective grounding is a challenge for today’s linemen as adjacent lines are heavily loaded, there are more sources of energy to guard against, and providing a safe work site can be challenging. It is hoped that this article will elevate the knowledge and appreciation of how much improvement has been made over the years. One thing for sure: Personal protective grounding has always been and remains a major element that can impact the safety of the lineman.

The Early Years

The lineman’s job quickly became one of the most hazardous occupations at the turn of the century. In these early days of electric power systems when lines needed to be worked on they were simply “killed” at the source of power. There were no lock out/tag out procedures to insure that inadvertent re-energization could occur. As might be imagined, serious accidents began to occur when lineman contacted energized lines that they thought were “dead” or had been “killed.” With considerable trial and error linemen discovered that grounding the conductors in some manner would improve their safety.

Some of the early lines were built with parallel lines that allowed one line to be taken out of service when maintenance needed to be performed. Linemen soon figured out the hazards of induction as they would experience being shocked when working on the de-energized line.

Lightning also presented a hazardous threat to linemen working on lines that had been de-energized. Lightning arresters were in their infancy and offered limited protection. It is easy to imagine the hazard to the linemen working on de-energized lines with no personal protective grounds installed, and a lightning strike occurred on the phase they were working on. After several serious accidents linemen learned not to work on lines during lightning storms.

As might be imagined, serious accidents began to occur when linemen contacted energized lines that they thought were “dead” or had been “killed.”

The Beginning of Protective Grounding

The beginning of protective grounding started in power stations. Around 1885, the first power systems were installed in larger cities to supply arc lamps for street lighting purposes. These early systems were comprised of direct current series circuits supplied by dynamos in power stations. These circuits frequently needed to be worked on and accidents occurred when circuits were inadvertently energized when being worked on.

The use of ground switches was one of the first measures used to protect workers when working on lines that were de-energized. Grounding switches were installed in power stations and were operated by the station operators. Lineworkers relied on these grounding switches as a means of ensuring the circuits were de-energized.

Early Methods

Portable grounding devices consisting of a grounding jumper and clamps that could be applied with a wooden handled stick. They were developed for use in power stations to ground equipment that needed to be worked on.

One of the early methods of protective grounding on lines was developed in the early 1900s. Lineworkers would lay out a length of wire long enough to reach the conductors on the pole and attach one end of it to a fire hydrant or water pipe. A rope was thrown over the conductors and attached to one end of the wire. The lineworker would then pull the wire over all the conductors, apply tension and secure the rope to the base of the pole or some nearby object. The concept was to create a short-circuit, which would trip out the protective equipment and provide a path to ground.

The next improvement was to utilize the same concept but the wire was replaced with a copper or brass chain. It was found that the chain would “bite” into the conductor and make better contact. This method was used for several years with some improvements made with the use of portable ground rods and connections to the grounding chain. The first edition of the Lineman’s Handbook stated that dry hand lines should always be used when installing grounding chains.

There were some efforts to test the lines and equipment to assure it was safe to apply protective grounding. A variety of homemade testers were developed and utilized. The “buzz” testing of using a larger mass of metal on the end of a wooden handled stick began being used. Testing before grounding was not widely done in the industry at this early stage.

Standardization Begins

The method of using portable wooden handled grounding devices in power stations was extended to lines and equipment in the field. Various homemade grounding devices with wooden handles were developed and used by power companies. Manufacturers such as the James R. Kearney Company also started to manufacture protective grounding devices.

The basic concept that became the standard was to always have a set of grounds between the work site and source of power. It was believed that in the event of the line becoming energized, the flow of current would be blocked from getting to the work site.

As the number of serious accidents continued to occur, it elevated the importance of protective grounding. Power Companies started to issue safety rule books and include requirements for the use of protective grounding. In these early days, it was not mandatory but left up to the discretion of the line foreman as to whether any grounds would be used or not. By the 1940s the use of protective grounds had become a common practice for most power companies as they realized that they could prevent serious injuries.

Research and Development

Prior to the 1940s, there had been no recognized studies regarding the severity of electric shock with respect to voltage and current levels along with their effect on the human body. Charles Dalziel (1904–1986) was a professor of electrical engineering and science at the University of California. In the 1940s and 50s he performed considerable research regarding electric shock involving humans and animals. Dalziel’s research resulted in valuable information, which became widely recognized in the industry and utilized to evaluate protective grounding methods. Two of his key conclusions were:

• The minimum current detected by the human body is 1.2 milliamperes.
• Ventricular fibrillation threshold is likely to occur when the current flow is above 1,000 milliamperes for 0.03 seconds.

Thanks to Dalziel’s research, the industry now had credible information for evaluating and optimizing effective protective grounding methods. Dalziel’s research is still referred to in today’s understanding and training regarding electric shock. Research and development was also being done by manufacturers related to grounding clamps, connections, and cables with regard to their ability to withstand fault currents that were increasing on many power systems.

In 1954 the Bonneville Power Administration con- ducted comprehensive testing of protective grounding on their systems. The following conclusions resulted from the study:

• The current practice of installing protective grounds on adjacent structures to the one being worked on, may not provide adequate protection for linemen if the line became energized.
• The short-circuiting and grounding of all conductors at the work location, using jumpers and clamps of adequate current carrying capacity, will likely provide sufficient protection for linemen if the line became energized.

Additional testing and studies were done by other organizations including Puget Power, Western Area Power Administration and American Electric Power. The A.B. Chance company also conducted various studies and testing on their way to becoming one of the key contributors to advancement of protective grounding.

This research and development resulted in more effective methods and higher-quality equipment. Studies also brought to light the hazard of step and touch potential, which had not been considered in the earlier days. It became obvious that effective training was needed for linemen to properly apply protective grounding.

Improved Methods and Equipment

With more experience to draw from along with the results of various studies, the industry made some significant improvements in procedures and equipment. Methods and procedures would now be established for protecting workers on the ground. OSHA began in the early 1970s and they developed regulations for protective grounding. The term Personal Protective Grounding slowly evolved into the standard term that would be used in the industry.

In 1990, IEEE Standard 1048 provided the first comprehensive guide for protective grounding of power lines. It included theoretical information on various applications. It also covered voltage detectors, ground set components, vehicle grounding, ground electrodes and testing of grounding sets. The standard was updated in 2003 and again in 2016. This standard is an excellent source of valuable information.

Two additional standards that enhanced the area of protective grounding included: ASTM F 855- Standard Specification for temporary protective grounds to be used on de-energized power lines. This is a comprehensive standard covering the design, materials, ratings and testing of clamps, ferrules, and cables. ASTM F 2249 -03- Standard specification for in-service test methods for temporary grounding jumper assemblies were used on de-energized lines and equipment. Experience had shown that protective grounds were not receiving the care they needed to ensure they remained in satisfactory working condition. This valuable standard provided excellent guidelines for inspecting and testing protective grounds.

The seventh edition of the Lineman’s and Cableman’s Handbook (1986) stated, “The protective grounds are installed in a manner to short-circuit the conductors so that the lineman and everything in the work area will be at the same potential.”

In 1994, OSHA issued a final ruling in the form of Standard 1910.269 Electric Power Generation, Trans- mission and Distribution—Rule (n)(3) “Temporary protective grounds shall be placed at such locations and arranged in such a manner as to prevent each employee from being exposed to hazardous differences in electric potential.”

Over time several methods and terms were used in the industry such as worksite grounds, master grounds, bracket grounds, single- point grounding, double-point grounding, etc. Equipotential zone grounding emerged as the standard term and method that the industry would adopt for the most part. Grounding and bonding were now used in a variety of ways to protect lineworkers in the air and on the ground. The importance of protective grounding training now became more widely realized than it had in the past.

Manufacturers continued to improve grounding clamps, connections, conductive mats, voltage testers, jumpers, etc. that allowed equipotential zones to be established under the various work site situations.

Conclusion

Like everything we have come a long way with improvements in the methods, tools and equipment associated with protective grounding. Protective grounding remains a key area of safety for electrical power systems workers. Today’s power grid has experienced considerable expansion and upgrading, which has affected protective grounding. Lines are more heavily loaded, fault current levels have increased and there are more energy sources on the transmission and distribution segments.

The various T&D projects that are being done on the grid can create some unique situations where the proper application of protective grounding can be challenging. We should all feel good about how far we have come and the methods, tools and equipment that are available to make the job safe. We also have come a long way in the training area. For any of the readers who are involved with training, NLC encourages the use of this article as a means for your trainees to understand how we got where we are today—it didn’t just happen!

The American Lineman
Alan Drew is renowned in the industry for his leadership, knowledge and the ability to plan. His book, The American Lineman, is a testament to those attributes.

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