Incident Prevention Magazine

After 25 years as a transmission-distribution lineman and foreman, Jim Vaughn, CUSP, has devoted the last 20 years to safety and training. A noted author, trainer and lecturer, he is a senior consultant for the Institute for Safety in Powerline Construction. He can be reached at [email protected].

Jim Vaughn, CUSP

Train the Trainer 101: Rigor and Discipline

The date was January 28, 1986. The event was the tenth and final flight of the Space Shuttle Challenger. Seventy-three seconds into flight, the booster rocket that was lifting Challenger into space exploded, killing all seven astronauts aboard.

When events like the Challenger explosion happen, you never forget where you were at the time. You remember the iconic photos and the national days of mourning for those lost. After the Challenger explosion, President Reagan appointed the Rogers Commission to investigate the disaster, and some of you may remember the news commentary on the Rogers Commission Report. If you didn’t study the reports from the incident, you likely aren’t aware of the stunning findings, the changes that were called for and, even more importantly, the effect the changes at NASA have had on industry – including the utility industry. It’s worth taking a look. You can read about lessons learned from the incident at https://ocw.mit.edu/courses/aeronautics-and-astronautics/16-891j-space-policy-seminar-spring-2003/readings/challengerlessons.pdf.

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Jim Vaughn, CUSP

October-November 2019 Q&A

Q: Are utilities required to have a written fall protection program that follows a written hazard analysis?

A: It’s not a bad idea because the process assures a fairly complete assessment of fall risks that makes training and protection of workers more effective. We know the source of your confusion because it’s a question we get often, and we’ve looked into it. It takes some deciphering, but here is how the confusion starts. We often hear of power and telcom companies reading OSHA 29 CFR 1910 Subpart D, “Walking-Working Surfaces”; seeing 1910.28, “Duty to have fall protection and falling object protection”; and begin writing complex compliance programs following the Walking-Working Surfaces rule. There is nothing wrong with a robust hazard analysis program that drives training, but if you are doing it to comply with a standard, you may not need to. If you read closely, you will find an exception for both telcom (see 1910.28(a)(2)(vi)) and electric power transmission and distribution (see 1910.28(a)(2)(vii)). The T&D exception relies on compliance with 1910.269(g)(2)(i).

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Jim Vaughn, CUSP

Train the Trainer 101: OSHA, Training and Certification

The occupational safety and health industry and civil authorities require that employers provide training to employees. In the U.S., OSHA mandates safety training related to tasks assigned to employees. The agency often also requires the employer to certify that the training has been completed. In fact, if you have an incident requiring OSHA notification, the first question that will be asked is, “Was the employee trained for the task?” The second inquiry will be a request for documentation of the training, usually followed by an enforceable subpoena for those training records.

Training and certification of training are important for two reasons. The first is that training has clearly been demonstrated to reduce incidents and injuries to workers. Second, OSHA will hold employers accountable for the training they conduct. The penalties for willful violation of training requirements are rarely discussed, and I hesitate to do it here, but the record shows that if an employer does not train, and OSHA can show the employer knew training was required, the penalties are based on willful violation. Penalties for willful violations that result in fatalities can include jail time for the employer. In addition, if OSHA wins a willful violation case, the employer can expect charges of negligence under both civil and criminal liability standards. Don’t take this training responsibility lightly. I, like OSHA, would prefer employers be compliant for the welfare of the workforce because they are ethical and care about their employees. But if the threat of prosecution works, we still accomplish the desired outcome: a safer workplace.

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Jim Vaughn, CUSP

August-September 2019 Q&A

Q: What is considered a forklift? We use wheel loaders equipped with accessory forks on our rights-of-way to unload and move poles and pole sections. We were told by our client’s safety inspector that the loader operators have to be certified as forklift operators because the loaders are equipped with forks. We have always used loaders and loader operators and never had an issue. Where do I find the information to resolve this issue?

A: OSHA refers to forklifts as powered industrial trucks or PITs, while the industry commonly calls them forklifts. OSHA’s construction standard has a section on material-handling equipment. The very last rule is 1926.602(d), “Powered industrial truck operator training.” The rule consists of a single note that states, “The requirements applicable to construction work under this paragraph are identical to those set forth at §1910.178(l) of this chapter.”

I have had people tell me that this rule means that operators of construction equipment using forks, like a loader, are required to be licensed or certified as a PIT operator. That is not the case. The PIT standard that contains forklift operation and training rules is found in the general industry rules. The second sentence of paragraph 1910.178(a)(1) states the following: “This section does not apply to compressed air or nonflammable compressed gas-operated industrial trucks, nor to farm vehicles, nor to vehicles intended primarily for earth moving or over-the-road hauling.” Wheel loaders are designed to move earth. They are not PITs even if they are equipped with forks.

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Jim Vaughn, CUSP

Train the Trainer 101: Manufacturer Warnings and OSHA-Compliant Safety Performance

Over the past few weeks I have received several inquiries regarding horizontal directional drilling (HDD). It’s not unusual in our industry for questions to make the rounds of utilities and contractors, generating interest and often controversy. I also have recently received several inquiries regarding OSHA allegedly canceling the digger derrick exemption in 29 CFR 1926 Subpart CC, “Cranes & Derricks in Construction.” OSHA hasn’t done that, but somebody said they did, and folks started asking around. Soon after, I received calls for clarification on the matter. In the digger derrick case, there was nothing to it; OSHA has not changed anything about the exemption. However, concerning HDD, there is an issue that raises an interesting question for those who administer compliance.

The point of the rest of this article is not to recommend or criticize any safety procedure associated with HDD. The point is to examine the role of manufacturer warnings and OSHA-compliant safety performance in the workplace. There is no doubt that I will get emails from HDD machine manufacturers and adherents of overshoe use, as well as overshoe sales or manufacturing representatives. I invite your response. To be clear, both Incident Prevention magazine and I are solely interested in providing an opportunity for perspective and analysis of a process that will help individuals learn how to deal with challenges in the workplace.

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Jim Vaughn, CUSP

June-July 2019 Q&A

Q: We experienced an event that has caused some confusion among crew and supervisors about what we thought we knew about grounding. We were working midspan on a de-energized 345-kV circuit. We drove a ground rod, grounded our trucks to it and grounded the phases to it. Almost immediately, we smelled hot rubber, and then tires started to smoke. Can you help us understand why this happened?

A: That was likely much more serious than hot tires. For the benefit of readers, we spoke with you on the phone, got details and shared opinions. Here is what happened: Your crew was in a right-of-way with very high induction. The ground rod you drove was very high resistance. When you connected your trucks, essentially you made a radial connection from phase to truck through the ground rod connection. In doing so, you loaded very high induction current onto the truck, which passed into the earth across the tires and outriggers. Many utilities by procedure use ground rods at midspans, and often it goes without problems. This is why we stress learning the principles of current flow in grounded systems. If you can ground phases to the very low-resistance static, the induction load is handled without much risk to workers on the ground. If you do have to ground your truck, and there is high induction, a well-driven rod isolated from the phase grounds might be a good choice. If grounding to the same ground electrode as the phases can energize the truck, as happened in your case, dangerous gradients can occur around the truck, and touch potentials between earth and truck can be deadly.

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Jim Vaughn, CUSP

Train the Trainer 101: Root Cause Analysis, Training and Lessons Learned

I’m not sure how I became an analyst. I don’t think it’s a career goal you necessarily plan for. My understanding of the analyst role is that it’s an individual who studies the elements of an event or occurrence. Analysts break down the elements of an event to learn how those elements are related. The purpose of analysis is to understand the nature of the event being studied. Through effective analysis, we ultimately create or assure desired outcomes and prevent or minimize the likelihood of undesired outcomes.

Over the past 10 years I have analyzed a half-dozen training accidents that occurred in apprentice training yards. Recently I also have seen a couple of videos of incidents involving apprentices in which no one was hurt; they were actually kind of funny to watch. But to an analyst, those videos have a lot more to offer than the lighthearted “been there” sympathy. Lineworkers often learn the hard way how not to do things. It’s that hard way that I want to eliminate because sometimes the hard way becomes the final act to what might have been a great life.

I was once engaged to write an opinion on a root cause analysis (RCA) that OSHA and a utility performed based on an incident that hospitalized three apprentices in a single event. OSHA only performs RCAs to identify where the employer may be at fault, but in this situation, the RCA listed all kinds of physical conditions and procedural mistakes that caused the incident. All of those items were causally related, but none were the real root cause. Before we move ahead in this edition of “Train the Trainer 101,” readers need to understand RCAs and how they fit into the lessons learned from training accidents.

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Jim Vaughn, CUSP

April-May 2019 Q&A

Q: OSHA’s digger derrick exception – found at 29 CFR 1926.1400(c)(4) – includes digger derricks when they are used for augering holes for poles carrying electric or telecommunication lines, for placing and removing the poles, and for handling associated materials for installation on, or removal from, the poles, or when used for any other work subject to 1926 Subpart V. Substations are included in Subpart V, so why do some people say setting steel or regulators is not covered by the exception?

A: You might try to justify substations as being in Subpart V – except for what the substation rules cover in Subpart V. OSHA 1926.966, “Substations,” is not about construction of substations. It is about working in substations. The rule covers minimum approach distances, guarding of live parts, switching and electrical safety. Steel erection, just like concrete work, falls under horizontal standards. 

The logical thinking of very reasonable people regarding this issue often is challenged for sensibility, mostly because of their perspective. For instance, if I can hang a capacitor on a wood pole with a digger derrick, why can’t I hang a beam and capacitor in a substation with a digger derrick? It’s the same thing, it’s a capacitor. The right perspective is that all construction-related lifting of loads by cranes is regulated under 1926.1400, except lifting poles and pole-mounted equipment that are installed using a truck specifically designed for digging and setting poles. 

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Jim Vaughn, CUSP

Train the Trainer 101: Telcom Workers Don’t Need FR – Or Do They?

The question that is the title of this installment of “Train the Trainer 101” originally came to me from a client during safety training for the company’s distribution employees. The client is a T&D contractor with a telecommunications (telcom) division. And yes, the question was regarding arc flash, which is not the same thing as FR. To utility workers, FR formerly meant “flash resistant.” The acronym FR was stolen from the utility industry by the road construction industry for traffic safety vests and now has come to stand for “flame resistant.” Flame resistance is the quality of a material designed for protection from exposure to fire or flame, not electrical arcs. OSHA, which does not use “FR” in the standards, requires that arc flash protective clothing also must be flame resistant to ensure clothing does not continue to burn after exposure to an electrical arc. In addition, flame resistance is required for the outer layer of clothing worn by an electrical worker who could be exposed to a heat source that could ignite that outer layer. There has been confusion, so it is important to recognize that use of the term “FR” on a traffic vest label does not mean the vest is arc protective; it is only flame resistant, meaning it has resistance to burning and will not continue to burn if the flame exposure is removed. It’s a habit to use the term FR when referring to arc flash protective gear, but we all need to understand the difference in labeling.

Now, back to the initial question. My first thought upon hearing it was that telcom workers are not required to use FR. After all, telcom is regulated by OSHA 29 CFR 1910.268, and 1910.268 does not require arc protective clothing like the 1910.269 standard does. But the answer doesn’t end there. So, if you are in the telcom business, don’t stop reading here. This is a lesson on interpretation of the standards as much as it is an answer to the question, who is required to wear arc flash protection?

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Jim Vaughn, CUSP

February-March 2019 Q&A

Q: We have crews working under a clearance on a de-energized circuit jointly controlled by two different utilities (employers). The concern is that the other employer’s personnel, wishing to bundle maintenance opportunities during the outage, are taking protective relays out of service on their end of the circuit. If a switch were inadvertently closed on their end, taking their relays out means no tripping protection since the other end of the circuit is open, too. Such an action could delay if not eliminate relay protection and raise current on the grounds protecting our workers. Is there an obligation between utilities to manage an outage under common rules?

A: There is an OSHA-based solution that comes in two parts. And even though your question is about grounding and tripping during inadvertent re-energizing, the solution to the issue actually lies ahead of grounding.

As you are aware, OSHA 29 CFR 1910.269(m) contains the rules for de-energizing lines and equipment for the protection of employees. That rule section is the pre-eminent means of ensuring no switch is ever closed without the permission of the employee in charge of the equipment or lines that have been de-energized and placed under their control. As you noted in your inquiry, we ground a circuit after the clearance process to ensure against any possibility of re-energizing. The grounding is based on an evaluation of relay trip settings to assure effective tripping to protect the crew under the clearance. Any change to the values or trip settings puts the crew at risk.

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Jim Vaughn, CUSP

Train the Trainer 101: Solving PPG – Without Electrical Math

This installation of “Train the Trainer 101” may have an odd title, but it was inspired by some recent conversations I’ve had. I’ve learned a lot about personal protective grounding (PPG) in the past 20 years, and I continually learn even more as others share their research and experiences. Some time ago I learned that much of the fundamental electrical math upon which electrical circuit theory is based does not adequately explain the risk from high currents imposed on grounded systems. That does not mean there are not theoretical explanations for all of the results in high-current fault testing. But the simple circuit math of Ohm’s law cannot explain the complex electrical physics that occur in a high-current fault, and that is partly what confuses the issue concerning EPZ.

What is simple is this fundamental of worker protection: It takes 50 volts to break the electrical resistance of a worker’s skin. If you can break the electrical resistance of the skin, current can flow, and the worker can be injured. However, if voltage cannot penetrate the skin, current cannot flow. You cannot eliminate system current by grounding; you can only divide it (i.e., send most of it through a different path) and hope for the best. But you can eliminate voltage in the worker exposure. You eliminate voltage potential by bonding. Once you’ve eliminated the voltage potential hazard, current no longer matters and thereby the risk is altogether eliminated.

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Jim Vaughn, CUSP

December 2018-January 2019 Q&A

Q: With all the talk about grounding, cover-up, EPZ and minimum approach distances, we have been debating the best practice for setting steel poles in energized 138 kV. A big question is, what class gloves should ground personnel wear while handling the pole? How can Class 3 or 4 gloves protect against 138 kV?

A: The short answer is that a Class 4 glove won’t protect against 138 kV. However, if you do it right, there is a very good chance you won’t be exposed to 138 kV even if you do get the pole in the 138. Here is how and why. At transmission voltages, we rely on planning, equipment setup, and precise/predictable control of the equipment and airspace to prevent contacts. We then take additional equipotential bonding actions to protect against a worst-case scenario like loss of control and pole contact with a circuit.

Here are some recommendations for those additional actions. Grade the work area. Grading the area flat around the pole hole gives the crew space for equipotential mats or grids. In best-case planning, it is ideal to stand the pole up with little hands-on contact until you get to the grabbers. If you are using portable mats, the prime location is at the stand-up/grabber location. During handling, the crew members on the pole butt will be in an EPZ. The pole then gets swung to the hole without crew contact. At the hole, mats are used to line the hole for crew who will handle the pole setting. Many crews are now using cattle panels as grids to create equipotential mats in the pole-setting areas. The panels are available at feed stores, constructed of welded #4 steel wire and bonded to the ground rod to create a large walking area around the pole-handling area that will be at equal potential with the pole.

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Jim Vaughn, CUSP

Train the Trainer 101: Are Those Tools and Equipment Approved?

We provide tools and equipment for our crews. Sometimes they are special tools, and sometimes they are generic tools necessary to support routine crew work. Sometimes they are accessories for trucks and equipment, and sometimes they are simply extra tools or equipment to make things easier on the people in the field. The question then is, are these tools approved?

The following is going to aggravate some readers, so let’s start with a reminder: I attempt to clarify and simplify compliance with this series. This is about making compliance easier and sometimes less expensive. So, here is an example.

About 20 years ago I was organizing a training school for a community college in Florida. I was recruiting utilities as clients. A visiting utility safety director saw that we had 40-foot-length retractables at the tops of the training poles. He said, “You are going to get into trouble with those yo-yos. They have to be mounted on approved davits.” My first question – and what should be your first question, too – was, approved by who? Without skipping a beat, the safety director responded, “OSHA.” We then went to his office where he had a similar device for which they had paid a little over $2,000. And just like he said, right there on the box was clearly printed “OSHA approved.” It only took me a few minutes on OSHA’s website to show him reference after reference and interpretation after interpretation in which OSHA stated to employers and manufacturers that it does not approve equipment. If an employer writes to OSHA and asks if they approve of having the employer’s employees in a specific type of exposure, and the employer intends to use a specific tool and equipment in a particular configuration, OSHA will respond that the agency does not approve equipment. The agency will then go on to state that in the situation described, using the equipment as described, OSHA believes the employer’s solution would – or would not – meet OSHA’s requirements.

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Jim Vaughn, CUSP

October-November 2018 Q&A

Q: We were recently sticking distribution for a small utility when the utilities inspector stopped us for not having safety latches on our hot hoist. We have now been told that OSHA requires safety latches, but we can’t find a rule for that in the OSHA 1910.269 standard. What are we missing?

A: This answer will surprise and confuse some safety folks, so we want to remind you that we are not necessarily advocating the information we provide – we are educating readers on the rules and best practices. In response to your question, you are not missing anything; there is no OSHA rule for our industry that requires safety latches on hooks. Latches make sense. With a latch, connections do not unexpectedly separate. However, hooks under strain do not unexpectedly separate either. Most hooks for hoists have a tab for installing a latch. Many come with latches, and many do not. In hot-sticking applications, it often is difficult to open a latch and remove a hook from a sling. OSHA does, however, have safety latch requirements for some vertical standards that have no effect on utilities.

Q: When does OSHA consider a pole hole an excavation requiring a barricade?

A: It depends on whether or how long the pole hole is open and/or unattended. The preamble has a discussion on pole holes in which OSHA, in a fit of practicality, agreed that if the hole is bored and the pole is set within a reasonable time – being tens of minutes – there is very little practical reason to install fall protection. However, if the hole is large enough that a worker could fall in even with the pole in place, then some measures should be taken. As a contractor, we would ensure spoils were stable and lay 6 to 8 feet of 12-inch scaffold board across the holes between pole and spoils to ensure stable footing and no void large enough that a person could fall through. The other issue is, a hole for what pole? Distribution is not an issue. Transmission starts to need activities for protection like the above. Some transmission holes are 50 inches for a pole that’s only 36 inches to allow for concrete ballast. Those are excavations. We know many contractors that have used half of a round hay-bale feeder from Tractor Supply Co. as a guardrail.

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Jim Vaughn, CUSP

Train the Trainer 101: The Value of a Site-Specific Health and Safety Plan

If you follow OSHA’s guidelines, you train your workers to perform hazard analysis. You probably have a tailboard process as well, although your company might have a different name for it. Tailboards and crew hazard analysis are fundamental leading indicators of a good safety program. But hazard analysis and tailboards are only two elements of what really makes a difference in a safe approach to work. A health and safety site-specific plan (HASSSP) and the HASSSP process bring with them innumerable benefits – not just prevention of unwanted incidents.

When I was a contractor safety manager, I wrote a site-specific plan for every project. I started doing so about 15 years ago, after a series of preventable incidents and conditions that wouldn’t have occurred if I had provided prevention information to the supervisor and crew prior to the events. It occurred to me that for all the planning our company did, we missed some pretty big issues – issues that cost us pain and treasure.

A health and safety site-specific plan is not just a contractor tool. Many utility projects will benefit from a HASSSP since the level of detail for the plan itself is relative to the type and complexity of the work. Contractor HASSSPs typically are more detailed and developed if the local area is new to the company and particularly if the contractor is hiring new personnel for the duration of the project. The HASSSP is the product of prework research and analysis of the worksite and conditions that can or will affect crew performance or success.

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Jim Vaughn, CUSP

August-September 2018 Q&A

Q: I am brand new to the safety side of contracting and need guidance on finding information about heat stress. There are lots of guides on assessing heat illness as it occurs, but what about industry practices to prevent heat stress? What do successful heat-stress prevention plans look like?

A: We have three recommendations for you. First, some state plan safety and health agencies – such as California’s – have mandatory program requirements that include trigger temperatures. When a worksite reaches such a temperature, certain site practices for heat stress must be employed. Section III, Chapter 4 of the federal OSHA Technical Manual (see www.osha.gov/dts/osta/otm/otm_iii/otm_iii_4.html) also has detailed information about heat hazard assessments and programs.  

Second, call your local hospital or favorite occupational medicine specialist and review your heat-stress prevention plan with them. In the past, I have offered to pay a fee to have a doctor visit a safety meeting to talk about prevention, although doctors usually will come to speak for free.

Third, do just as you have done: Ask questions, and share information with individuals and companies that have good, effective programs.

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Jim Vaughn, CUSP

Train the Trainer 101: Enforcement of Vehicle Weight and Load Securement Rules

In the past few months, I have received comments and inquiries from all over the U.S. regarding what appears to be stepped-up enforcement of both load securement and vehicle weight rules. It’s not unusual that these topics garner attention from the U.S. Department of Transportation when it comes to carriers, but this recent uptick seems to be for smaller commercial vehicles, mechanics trucks, pressure diggers, and bucket and digger derrick trucks.

Not all utility safety professionals may be up to date on this topic because DOT issues are not front-burner issues. Typically, the human resources department handles a driver’s qualification file and drug testing for the DOT. Drivers at utilities only spend a few hours a week on the road between calls and jobs, idling most of the workday. We recognize that there are utilities with rigorous DOT management programs for equipment and drivers, but generally we find a more lax daily inspection protocol among utilities and contractors than you would find with a carrier. That might be justified considering the time a utility truck spends in transit compared to a carrier that is preparing to put a rig on the road with two drivers for 20 hours a day over the next two weeks. But it’s not the rule, and mistakes or latitude over trucks can suddenly become a serious liability when one of those overlooked trucks loses a steering link as it is driven through a school zone full of first-graders.

Craft Worker Compliance
Recently there have not been any changes of note in the rules for vehicle weight and load securement; however, it appears that some of the latitude taken by utilities, if not given by the DOT, has caught the attention of those responsible for enforcement of the rules. 

In the last couple of years, state enforcement agencies used local media to inform local commercial businesses – that are not carriers – that they would be stopped if they did not appear to comply with loading and marking standards for their class of vehicles. In Arizona, New Mexico, Washington and Colorado, my colleagues and I began to hear of roadside stops involving lawn maintenance companies and small construction concerns that were pulling dual-axle, 5-ton trailers behind a Ford F-350, carrying loaders, backhoes and super lawn machines. That soon extended to power company trucks, especially those loaded with large wire reels. I even heard of one instance in which state enforcement set up scales in a shopping center parking lot on a well-known route out of a power company service center. Within 40 minutes they cited 22 vehicles for being overweight. You would think drivers would have warned others, but the DOT waved them into the parking area before they started weighing and inspecting the vehicles, so no one knew what to expect. It shouldn’t have been – but it was – a big surprise for that utility’s fleet management to learn what kind of loads lineworkers were putting on those trailers.

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Guest — Sawake
am interested in some of this training especially on hot sticks
Tuesday, 17 July 2018 23:35
Guest — Michael Well
Hi Jim, a great resource on Enforcement of Vehicle Weight and Load Securement Rules. Well, vehicle weight needs to be figured out ... Read More
Wednesday, 05 December 2018 07:30
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Jim Vaughn, CUSP

June-July 2018 Q&A

Q: Whenever we see graphics for single-point grounding, it’s always a cluster, a connection to the neutral, a connection to a phase and a chain connecting to the other two phases. But when we check with other utilities or consultants, we see all kinds of arrangements, such as bracket grounds with a single point or two sets of single-point grounds bracketing the workspace. Where do we find the definitive arrangement, and why are there so many variations?

A: Under OSHA, the employer is solely responsible for determining how they will meet the requirements of 29 CFR 1910.269(n)(3), “Equipotential zone,” which requires that grounding of de-energized phases be installed in an arrangement that prevents employees from being exposed to differences in electrical potential. In addition to 1910.269(n)(3), there also is Appendix C to 1910.269, “Protection From Hazardous Differences in Electric Potential,” as well as IEEE 1048-2016, “IEEE Guide for Protective Grounding of Power Lines,” a consensus standard that may be considered the authoritative best practice. IEEE 1048 is filled with detailed electrical data – from modeling to application – to explain how to create equipotential protection and effective tripping of grounded circuits that may inadvertently be energized.

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Jim Vaughn, CUSP

Train the Trainer 101: Current in Grounds Can Kill

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.

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Jim Vaughn, CUSP

April-May 2018 Q&A

Q: Recently an event occurred during a trouble job that surprised us. We had an underbuild phase down that was broken midspan. Our crew was working from an insulated bucket, and we grounded both the feeder we were working on and the one above. While our crew was beginning to crimp the splice for the repair, an energized line a few spans away came in contact with the grounded phase our lineman was in contact with. The lineman was in an insulated bucket, but he still received a shock. He was not seriously injured. Can you help us understand this?

A: The explanation is simple. Grounded circuits will still have current flowing through them if they are energized. Where there are resistances in parallel paths with the grounded circuit, there will be a voltage drop and there will be current flow through the parallel path. The current level is limited by the resistance in the path. Insulated bucket trucks are not totally isolating. To confirm that, all you have to do is look at the electrical tests performed on insulating booms. The current flow on an insulating boom is limited to a value well below the current necessary to injure a worker. In your case, there was voltage drop in the gap between the grounded, energized phase and the insulating boom that was a path to ground. Your lineman bridged that gap when he was in contact with the phase while standing in the bucket. The voltage was high enough to penetrate his skin so that current could flow. He was protected from injury by the current-limiting function of the insulating boom. We know it takes about 50 milliamps of current through a worker to rise to the level of injury. Depending on the electrical integrity of the boom and the voltage involved, there were – and this is just a guess based on boom-test protocols – perhaps 50 microamps to 1 milliamp of current that could flow on the boom. That is well below the level of injury. Electrical integrity of the boom is paramount in protecting workers. That is why it is critical to wash and maintain the boom.

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