April – May 2022 Q&A
Q: Why are communications systems bonded to a utility system neutral? Doesn’t that make the communications messenger a parallel neutral path?
A: Yes, it does, but this is a case of “Which is worse?” There are a number of things we do for one purpose that create hazards for another. We must know the issues and choose what we will do. Down guys are one example. In transmission and distribution, many utilities install insulators in the upper section of a down guy to isolate it from the electrical environment at the top of the pole. The purpose is to protect the public from the potential of a hot guy. Then the engineer calls for a bond connection below the insulator to ground the guy, further ensuring the guy cannot become energized, again to protect the public. But the protection of the public endangers the lineworker. The bonding of the down guy connects the guy to the neutral or the transmission static that is bonded to the pole bond. Current follows every available path, so current from the neutral divides down the guy into the earth through the anchor. It’s the same for the static. It has induction from the parallel transmission conductors flowing to earth through the pole bond. An unwitting lineworker could – and this has happened with deadly results – open the path at the anchor and get between the down guy and the anchor. The public can’t be trained to recognize this potential hazard, so we train lineworkers to recognize it.
The same goes for the communications worker. OSHA 29 CFR 1910.268, “Telecommunications,” requires bonding of all conductive components on the pole to the utility pole bond, which is typically also bonding the neutral to earth. The benefit is that any differences in potential are bonded out. If the potentials are equal, the communications worker can’t get shocked. If they can’t get shocked, no neutral current in the system can enter or harm the communications worker. It’s the same at midspan. If a messenger comes down or is open, it is bonded to the neutral and both tangent structures. Any open in the messenger is bonded across by the neutral, limiting the risk of an open parallel-path hazard. It is the task of training developers to be sure to inform trainees and apprentices as to the nature of multiple paths and current flow in grounded systems so that they can take the proper precautions in the field.
Q: Where do we find the rule requiring bonding of man baskets to a grounded bus in substations? We are having a discussion about adding this requirement, but we can’t seem to find it.
A: The rule is a general requirement that does not specifically mention aerial lifts or man baskets. The rule is based on the two requirements of grounding to protect workers, which are to (1) trip the circuit and (2) equalize any potentials in the workers’ environment so that they are not exposed to any hazardous potential differences. As Appendix C to 1910.269 points out, these requirements can be met by either organizing grounding conductors in an equipotential arrangement or by adding connections to achieve the equipotential environment.
Paragraph 1910.269(n)(3), “Equipotential zone,” is the preeminent rule. The rule states the following: “Temporary protective grounds shall be placed at such locations and arranged in such a manner that the employer can demonstrate will prevent each employee from being exposed to hazardous differences in electric potential [italicized for emphasis].” That last phrase about protecting the employee from hazardous differences in electric potential makes basket bonding a requirement. If the grounded phases are subject to being inadvertently energized, subject to induction voltage, or if they are current coupled, any path to ground will carry that current. If a conductive lift is used, it is a path to ground. A worker in a basket that is not electrically bonded to the grounded bus will be in between the current-carrying bus and the path to ground through the boom.
Appendix C to 1910.269 also offers additional guidance requiring bonding in part (III)(D)(2)(ii), titled “Ensuring that the potential differences between conductive objects in the employee’s work area are as low as possible.” The first paragraph of that part states, “To achieve as low a voltage as possible across any two conductive objects in the work area, the employer must bond all conductive objects in the work area. This section of this appendix discusses how to create a zone that minimizes differences in electric potential between conductive objects in the work area.”
By the way, our readers who are electrical engineers will notice the use of the phrase “electric potential” in this article. We know that is improper usage and that “electric” and “potential” mean the same thing. However, that is the usage in the OSHA standard, probably for clarity for uninitiated readers, so we are bound to use it here.
Q: What policies are you aware of that address 1926.1410 crane/drill rig work in proximity to energized conductors, specifically transmission voltages? In particular, what is required for a field policy that allows for a crane to work closer than Table A around an energized transmission conductor?
A: This is a gray area that requires some knowledge of how OSHA views rules and the differences between the 1926 Subpart V standards and the Subpart CC/1926.1400 “Cranes and Derricks in Construction” standards. Digger derricks are exempt from 1926.1400 qualified crane operators for power-line work (except in some state plans). Cranes are not exempt. However, Table A is about non-electrically-qualified operators, and working within Table A requires the operator to consult with the utility owner for guidance. If the operator is the utility, they have all the qualifications necessary to do the work safely within the Table A clearances using the utility’s own MAD-related standards. This is not specifically called out in the 1926.1400 standard. It is pretty clear if you examine the rules for intent and what the rules and OSHA guidance are trying to accomplish, which is preventing contact with the power line that could result in injury to workers. Yes, “injury to workers” is a qualified statement. You can contact the circuit, burn it down and smoke the crane, but you don’t have to report that to OSHA unless someone is hospitalized or killed.
In order to protect workers, there are procedures called out by the rules that intend to prevent employees from the hazard of an electrical contact. If the crane is not operated by an electrically qualified operator (a qualified lineworker), then the operation must comply with 1926.1400. That includes outside Table A clearances, barricades, observers, demarcation, paint on the ground and so forth. With drill rigs, choice in capabilities matters. A rotating table drill rig that doesn’t have a hoist with a hook (many do) is not a crane and is covered under 1910.269 or 1926 Subpart V.
If your drill rig has a cable and hook and rotates, it meets the criteria for a crane found in the 1926.1400 scope. This is arguable in our industry but not to OSHA, at least until someone tests it in court or interpretations. In power-line work/pole foundations with an electrically qualified operator, the operator of the crane must be 1926.1400 compliance-certified as an operator. But if your crane operator is the power company, that makes the 1926.1400 requirements for fewer than 20 feet sort of moot since you can figure out the limitations yourself. The low-drill or pressure-drill rig doesn’t have to have a 1926.1400 qualified crane operator. Still, the operator must be certified by the employer as qualified to safely operate. So, whether it’s a crane or not, with a qualified operator, it’s as simple as a tailboard with a detailed discussion of hazards identified, procedures established, observation and clearances.
Q: We are having conflict within our utility about who is qualified to enter the substation. We have found that the standards that are available are somewhat thin on details. It would be great to have a list. How do we resolve this?
A: Any qualification criteria begin with the OSHA 1910.269(a)(2) requirements. In brief, the basic criteria are that each qualified employee shall be trained and competent in:
- The skills and techniques necessary to distinguish exposed live parts.
- The skills and techniques necessary to determine the nominal voltage of exposed live parts.
- The minimum approach distances specified in this section corresponding to the voltages to which the qualified employee will be exposed and the skills and techniques necessary to maintain those distances.
- The proper use of the special precautionary techniques, personal protective equipment, insulating and shielding materials, and insulating tools for working on or near exposed energized parts of electric equipment.
- The recognition of electrical hazards to which the employee may be exposed and the skills and techniques necessary to control or avoid these hazards.
But that’s not an all-inclusive list. The rules also include requirements that entrants shall be trained in and familiar with safety-related work practices, safety procedures and other safety requirements, and each employee shall be trained in and familiar with any other safety practices, including applicable emergency procedures. We think we know where some of the issue lies, and it’s not uncommon. Substation operators and crews don’t like to have unqualified personnel roaming around their substations; this includes engineers who feel their engineering credentials are qualification enough. Unfortunately, those credentials do not equal substation entry qualification unless the credentials include training by the employer specific to the hazards of substations. This is no criticism of engineers and their accomplishments. It takes years of hard work to get there, but that hard work does not include the specific analysis and training associated with substation entry. Everyone who enters a substation – from the gardener to the president – must have the utility-specific training meeting the criteria established by OSHA.
OSHA establishes compliance outcomes in 1910.269(a)(2) qualification without specifications, knowing that there are things that occur in substations unique to the operating characteristics that can cause hazards unique to the operating system. There are automated operations that expel debris jets that become hazardous. There are grounding and bonding inspections required by entrants. There are SCADA remote operations and barricaded areas uniquely controlled by a crew-owned clearance as well as multicrew procedures that are under the purview and control of a local crew in the substation. There should also be entry notification procedures that are trained on, and qualification conferred through the employer’s OSHA-compliant procedures.
Each substation employer/owner is expected to establish qualification and control of their substation and develop and deliver training to all personnel who enter the substation. Those procedures and training must be documented, and they must be defensible and compliant with the expectations of the OSHA standard and the consensus standards, particularly the National Electrical Safety Code. Good luck and don’t take it personally. Bad things have happened to unsuspecting people when we don’t get this right.
Do you have a question regarding best practices, work procedures or other utility safety-related topics? If so, please send your inquiries directly to firstname.lastname@example.org. Questions submitted are reviewed and answered by the iP editorial advisory board and other subject matter experts.