Skip to main content


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 Utility Fleet Professional 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.

The Initial Question
The initial HDD question I received focused on the use of dielectric overshoes by trackers, those workers who follow the cutting end of the bore string for the HDD rig. The question was, does a tracker need to wear dielectric overshoes for protection from step potential should the drill contact energized cables? My first reaction was no, I don’t believe there is a hazard to the tracker. That might surprise the reader as the risk may seem obvious, but of course, it’s not as simple as that.

The person who asked the question then said that the manufacturer of their company’s HDD machines had just finished annual training on HDD safety and provided updated operator manuals. The newly updated manuals require dielectric overshoes for the tracker if there are electrical obstructions within 10 feet of the bore-path plan. That revelation raises an interesting issue. In deciding what remediations are appropriate for a recognized threat, the employer performs an analysis. Hazard analysis can have many components, including an assessment of likelihood and frequency of exposure, as well as issues with remediation. The analysis often is rightly calculated from the history of events and prior experience with similar hazards or occurrences and the results tabulated therefrom. I am not an expert on HDD, but in some 40 years of industry experience with the practice, I have never heard of any electrical fatalities experienced by trackers or operators. In an analysis of risk performed by qualified industry experts whom I contacted, none of those experts was aware of any step-potential incidents, and they tended to agree there is little risk to the tracker from step potential. I also read dozens of articles on HDD safety. I found one incident from 2018 that involved a worker who was shocked. I called the compliance safety and health officer (CSHO) in charge and learned there were a series of performance issues that led up to the contact. All of the articles on HDD safety that I found in 20 hours of research mentioned the potential for electrical strike hazards, but the only injury data or events mentioned were related to gas strikes and workers caught in turning equipment. Data from NIOSH’s Fatality Assessment and Control Evaluation program turned up no instances of electrocutions associated with HDD. I was even contacted by a troubleman from a large Western U.S. utility that had several trouble calls over the years where crews drilled into 4-kV and 15-kV feeders. The 4-kV delta did not relay until the second phase was penetrated, meaning the bore bit was energized for some period of time before the feeder protection cleared the fault. In all the incidents, there were no shocks reported. In fact, the crew not only didn’t feel any shock, they didn’t know they had penetrated a primary underground feeder.

All of the industry experts I sought out for their opinions agreed that, in principle, there is a possibility that an electrical hazard is present during an HDD strike, but the experience record suggests the risk is very low, if any. In all likelihood, the steel bit, in intimate contact with the flooded borehole, would easily ground the electrical field and not result in gradients on the walking surface above. It also was universally observed that a greater risk was likely touch potential at the machine, in particular at the initial borehole entry, although again, there was no record or knowledge of any such event by the experts queried. Some observers likened the level of risk to backhoe operation. Many have firsthand knowledge of dig-ins with shoveling crews in the ditch, yet none were aware of electrical contacts by those standing near the contact location. Still, the logic that a hazard exists and that a gradient could appear is undeniable if viewed from the perspective of currents flowing in earth. So, an employer could argue that there is little risk based on an experiential and a theoretical basis. The last historical observation comes from OSHA. The agency produces informational bulletins on particular hazards, typically including fatal facts or incident reviews to support the purpose of each bulletin. OSHA Safety and Health Information Bulletin 03-13-2018, “Avoiding Underground Utilities During Horizontal Directional Drilling Operations” (see, mentions electrical risks but only references an OSHA incident in which workers were injured by a gas ignition after a strike. A survey of several years of fatal facts and incident reports turned up no electrical incidents associated with HDD.

On the other hand, if there is a calculable level of risk, there is an OSHA principle that requires remediation of the perceived risk. The agency has a common approach to risk that states that if a known risk is calculable, the employer should determine the level of risk. Further, if the known risk can’t be calculated, it should be assumed hazardous and the appropriate protection of employees should be employed. As an industry, we have the theoretical modeling tools available. We use them in substation grid calculations. The problem is that a flooded borehole ground resistance is not easily modeled or calculated.

Risk Estimates and Instructions
So, where does an HDD machine manufacturer get its estimate of risk from, and what is the purpose of the manufacturer’s instructions? An industry insider told me that most of the operators to which manufacturers sell HDD machines are not electric utility operators or contractors. Most are gas, water or communications utilities or contractors where the machines are operated by skilled labor with little to no electrical hazard training. The advice given by the HDD equipment manufacturers is objective safety guidance for operators who may not be aware of the risks associated with a dig-in. There also is another aspect of the manufacturer’s agenda: liability exposure. It’s a very simple matter of perceived exposure easily remedied by a broad requirement for dielectric overshoes and rubber gloves. This is not a criticism of HDD machine manufacturers. In fact, in my review of the materials available online, manufacturers have done a remarkable job developing monitoring and warning systems to detect strikes, as well as developing training and warnings to keep operators safely on the machines and workers clear of touch potentials. But what about the old and common belief that OSHA can cite an employer for not following a manufacturer’s safety recommendations? Can a manufacturer’s operating guide, based on the manufacturer’s concern for liability protection, establish a worker safety procedure liability for a whole industry? Perhaps not, based on a survey of the OSHA standards.

I found numerous instances in OSHA’s 1910 and 1926 standards that require the employer to follow manufacturer instructions. All of the instances have a common theme related to design. In every case examined, the rule specifically applied to the integrity of structures or design factors and procedures crafted to limit employers from exceeding those design limitations. In every case, the OSHA instruction to follow manufacturer designs or procedures was done so to prevent dynamic failures of equipment that would result in risk to workers. Examples include 1926.302(b)(5) regarding manufacturers’ safe operating pressures for hoses, pipes and valves; 1917.43(b)(1) regarding forks on industrial lifts; 1926.1412(b) regarding repairs and adjustments to equipment; 1926.1404 regarding rope use; 1917.42(b) regarding wire rope; 1926.1404(q)(1) regarding manufacturers’ specs on outrigger beams; 1910.243(d) regarding powered tool applications; and 1910.243(e) regarding lawn mower use. Yes, there is a standard covering lawn mowers.

In every case, OSHA’s duty to follow procedures – with “procedures” defined in 1926.1401 as including but not limited to instructions, diagrams, recommendations, warnings, specifications, protocols and limitations – is related to maintaining design criteria. OSHA does address the duty implied by knowledge of a hazard and a remediation in the CSHO’s guidance on making a case under the General Duty Clause. In OSHA’s Field Operations Manual for compliance offices (see, the justification for a citation under the General Duty Clause requires several criteria, including the employer’s implied knowledge. On page 4-12 of the manual, a portion of paragraph 6(a) states, “Employer awareness of a hazard may also be demonstrated by a review of company memorandums, safety work rules that specifically identify a hazard, operations manuals, standard operating procedures, and collective bargaining agreements. …” On the next page, under the “Industry Recognition” section, the field operations manual mentions “[m]anufacturers’ warnings on equipment or in literature that are relevant to the hazard.” But in the same section, OSHA qualifies that industry experts with knowledge of the condition are a legitimate source regarding hazards. So, what happens if those experts contradict the assumptions made by a machine’s manufacturer? After all, there is no empirical evidence that step potential could occur.

To further confound the process, the manufacturer’s requirement is to use dielectric overshoes. These overshoes do have a role in the protection of electrical workers, but it is a limited one. I have no doubt that dielectric overshoes in good condition will provide a measure of protection from the lower voltage that is encountered in a ground gradient. Dielectric overshoes are designated as a secondary line of protection, meaning they are not to be relied on as a primary means of protection from an electrical exposure. My biggest concern for the efficacy of dielectric overshoes comes from the testing standard that requires a “ramp-up” of test voltage to ensure performance when, in actual use, there is no ramp-up of exposure. ASTM F1116, “Standard Test Method for Determining Dielectric Strength of Dielectric Footwear,” and ASTM F1117, “Standard Specification for Dielectric Footwear,” both qualify testing as only being accurate at the time of the test. There is no in-service testing protocol for periodic evaluation of the efficacy of the protection provided by the footwear. I am not too sure about the performance of muddy, sunbaked, rubber dielectric shoes with punctured soles that have been worn all day by a nonelectrical HDD crew boring in gas pipe. The last issue with dielectric overshoes is a recurring conversation from industry safety personnel concerned that the weight and fit of the overshoes are issues when it comes to back and knee strain. Again, there is no empirical evidence that these overshoes are a musculoskeletal issue, but anyone who wears them will have issues and an opinion.

A Perfectly Unusual Example
So, here lies a perfect example of how to assess all aspects of risks, yet it’s an unusual example of contradictions and policies that leave the safety manager with few choices. In summary, the safety manager is obligated to do two things: protect the worker and the employer. Here we have defensible assumptions based on principles of current and resistance that suggest risks associated with gradients and touch potential at the machine. Then we have defensible conditions of history, and experts who agree there is little step-potential risk for the tracker and little risk to the operator who stays on the isolated machine. We could just require PPE (overshoes), but we have reasonable concerns with long-term ergonomic drawbacks and issues with qualified users, in-service maintenance and limited application of overshoe efficacy. Next is consideration of the HDD equipment manufacturer’s legitimate civil interest, which no doubt includes the user’s protection but not necessarily because of certain incidents. Then we are addressing the issue without empirical guidance. Lastly, we have to consider the General Duty Clause, in particular the citation criteria, not the actual evidence of a risk. But why would you be concerned about General Duty citations if you were certain no one was going to be fatally injured, prompting OSHA’s involvement?

As a consultant to utilities, I recommend following the manufacturer’s instructions. But I also recommend specific training regarding the exposures and risks of musculoskeletal complications with long-term use of dielectric overshoes and the limited protection the shoes provide. Put greater emphasis on eliminating the risk of underground utility strikes by establishing written procedures that include effective underground facilities location followed by potholing to define locations of underground obstructions. With the technology we have today, it is very reasonable to assume that we can bore without strikes. And finally, having written the most eloquent of procedures, follow up with audits and accountability to ensure performance in the field results in prevention. After all, every assumption of what could happen and all the monitors and PPE a worker can bear are less effective than no incident at all. As always, I invite and value your comments and experiences.

About the Author: 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

After 25 years as a transmission-distribution lineman and foreman, Jim Vaughn, CUSP, has devoted the last 22 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].