Q & A Archive

Q: We are looking for some direction and opinions regarding SF6 gas switches. The SF6 switches we use on our campus are older and starting to pose problems. Some are leaking and others are very difficult to operate. Can you help? A: Sulfur hexafluoride, or SF6, isn’t a topic or problem we can effectively deal with in this venue, but we can offer some direction along practical lines as SF6 has greatly fallen out of favor with regulatory agencies and – as a result – the industry as a whole. We understand that several states have SF6 “remove from service” dates on their environmental calendars. SF6 is nontoxic and nonflammable, but it is a huge issue among environmentalists as a primary greenhouse gas contributor. If your SF6 gas switches a…

Q: How high can we stack poles in a pole yard? I can’t find any references in OSHA or ANSI C2/the National Electrical Safety Code. Is there a standard? A: Your question provides us with an example of when a standard governing our industry is not necessarily found in the National Electrical Safety Code, OSHA 29 CFR 1910.269 (General Industry) or OSHA 1926 Subpart V (Construction). What you will find is that there is no specific standard for pole piles; the rules for stacking/storage of materials are the same for every industry. Those rules are found at OSHA 1910.176 and 1926.250, in particular 1926.250(b)(9) for “cylindrical materials.” The objective is safety in storage, access and handling as each of the rules for materials requires tha…

Q: Why don’t all utilities use rubber gloves with hot sticks? A: One of our supporting consultants sent us this question that he gets all the time. The answer is simple: There is no requirement in any standard to use rubber gloves with hot sticks. Rubber-gloving hot sticks has evolved as a work practice in the last decade. There is nothing wrong with choosing to use rubber gloves with hot sticks, and lineworkers have been known to do so during wet or snowy conditions. But many lineworkers with more than 20 years of experience will tell you that we never used rubber gloves routinely with hot sticks and never had an issue with that practice. Why is there no requirement? Well, that’s based on history. The inspection and maintenance protocol…

Q: We recently participated in a safety seminar during which OSHA’s digger derrick/crane exemption was discussed. We have used the exemption with digger derricks to raise baskets of travelers to pole-tops for wire-pulling installation. Are we in compliance if we are not using a certified crane operator for this work? A: Our interpretation of the OSHA rule indicates that your use of the digger derrick exemption is incorrect. Here’s a little history: OSHA’s Cranes and Derricks in Construction (29 CFR 1926.1400) final rule of 2010 included the exemption of digger derricks. In October 2012, OSHA published the direct and final rule, clarifying the digger derrick pole truck exemption from the Cranes and Derricks in Construction standard and as…

Q: We were driving ground rods with a hammer drill for a switch pad on a construction site when OSHA inspected the site. OSHA was there to see the general contractor, but they cited our crew for not using a ground fault circuit interrupter (GFCI) where we were plugged into the site’s construction temporary. That brought up these questions: Why GFCI? What does GFCI do and how does it work? A: The GFCI or GFI (ground fault interrupter) was invented by University of California at Berkeley Professor Charles Dalziel. A GFCI does not limit voltage; you can still be shocked, but you won’t be killed if the GFCI is successful. In a tool or appliance circuit, the GFCI operates at the speed of light when it senses a current imbalance between the ho…

Q: Our network group employees don’t work anything over 600 volts without working clearance. When working 480 volts, can they wear Class 2 sleeves with Class 0 gloves? We’ve looked through OSHA 29 CFR 1910.269 and are unable to find where it says they can’t. A: We applaud you for attempting the research. OSHA’s perspective on the standards is to tell employers what they must accomplish (not how to accomplish it) or not to do it. Most of the time, your research begins with OSHA regulations. We look to them first because they are statutory and what we must answer to. When we understand OSHA’s expectation, we can then go to the related consensus standard for best practices. The answer to your question is that it is not prohibited to don Cla…

Q: With distribution URD cable and other circuits in the same duct bank, should there be any concern about inductive current/voltage on the conductor if there is a fault on the opposing circuit? Most of our circuits are in plastic conduit and encased in concrete. We have a neutral running through from the substation, and the vaults are grounded to earth with it all tied together. We also still have some lead cable (PILC) in our system. A: There are several conditions to your answer. For the poly-dielectric insulated, if the cables are not jacketed, the concentric in a common conduit will be in contact, so they are not truly isolated. If the cables are jacketed, they may be considered isolated. The reasoning is that since the concentric i…

Q: Is there a rule that determines at what voltage level we must ground downed primary (e.g., at voltages higher than 4 kV)? A: No, there is no rule that you must ground downed primary when working to get it back up in the air. When conductors are on the ground, the objective of grounding is twofold. The first objective is to help collapse the voltage and trip the circuit should the circuit inadvertently become energized while crews are working on it. The second objective is to aid in bonding the conductor close to the potential of earth where the workers are in contact with the downed conductors; this is to keep the voltage low between conductor and earth. Both of these objectives help to limit the hazard. Grounding does not remove the …

Q: How do consensus standards apply to the employer responsibility for safe work practices? Are they absolute? A: No, consensus standards are part of a system the employer can use to develop their safety programs. The issue is, can the employer defend their programs that do or do not conform to the consensus standards? Compliance with a consensus standard does not ensure compliance with OSHA. In fact, OSHA has clearly defined the role of consensus standards as useful for the employer in complying with the more performance-based requirements of the OSHA standard. “Performance-based” refers to how OSHA rules tell the employer what must be accomplished but do not dictate how the employer accomplishes compliance with the rules. The definitio…

Q: Is it ever OK to put a man basket on a crane? My understanding is that OSHA 1926.1400, “Cranes and Derricks in Construction,” states doing so is prohibited.   A: For our readers, the rule you are referring to is 29 CFR 1926.1431(a), which begins, “The use of equipment to hoist employees is prohibited …” The rule goes on to list the basis for exceptions. For line construction, an exception centers around two provisions: the need for access and safety. In a transmission corridor, there are often parallel circuits. An articulating boom in a conventional bucket truck would put the boom elbows in hazardous proximity to adjacent circuits. Additionally, in the past, crane booms had reach that could not be matched by conventional bucket truck…

Q: Why does grounding alone not prevent static discharges, and why don’t we have to ground all flammable dispensing drums and stations? A: “Flammable” is a relative term, and some of the written standards are detailed to the point that they can be confusing. The best thing any facility can do is to consult a chemist, chemical engineer or fire science specialist to survey and equip your flammable operations. The simple explanation has to do with volatility, which is how easily a chemical vaporizes and then how flammable that vapor becomes and at what temperature. Every chemical in the workplace should have a safety data sheet that lists the material’s vapor point and relative flammability. The issue then is the material’s vapor flash poin…

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 t…

Q: Is it a good idea to wear dielectric boots in a substation? Do they provide additional protection to a worker? We feel that the worker is at equipotential – given the grid and stone are maintained per design – so we don’t believe that dielectric boots would provide extra protection. What are your thoughts? A: The design of the substation’s grid has two purposes in its construction. One incorporates ground rods to create a low-resistance electrical path to get harmful voltage and current into the earth to protect the equipment in the station. The grid itself helps by interconnecting the rods. To most of us, the second purpose is more important. The grid creates a plane of bonded equipotential across the ground in the substation. The cr…

Incident Prevention magazine still receives many questions about the different facets of equipotential bonding. In this installment of Q&A, we provide detailed answers to several of the most frequent questions in an effort to help the industry better understand and resolve these issues for the safety of their workers who use temporarily grounded systems. Q: We have heard that we should be bonding baskets to the grounded transmission or distribution bus to equalize voltage differences between the basket and grounded phase. The idea of using a jumper bond from an insulating aerial lift to the grounded overhead conductor is new to everyone. How does this work, why do we need to do it, and how should we do it?

Q: We are contractors with a truck grounding question for work inside substations. Working within a proper clearance, the generation and transmission cooperative (G&T) that owns the transmission circuit coming into the substation believes 4/0 equipment grounding is needed, while the consumer utilities operating the substation say 1/0 or 2/0 is required. We sometimes are required by the G&T to use double 4/0 to meet the required available fault current. Can you explain the disparity in requirements? Also, do we meet the OSHA requirements if we use the 1/0 or the 2/0 for equipment grounding on manlifts when working within the minimum approach distance in a de-energized area that is locked out and tagged out?

Q: We have been reading OSHA 29 CFR 1910.269 regarding two-man work, but we cannot find a definition for “routine switching.” We are under the impression that a trained troubleshooter can replace blown fuses in cutouts without a second man. Since it is not specifically mentioned in the exceptions, do we have this wrong? We have old porcelain cutouts on our 4-kV system where you cannot remove the door with a stick and must grab it with your hand, putting the worker within the minimum approach distance of the energized 15-kV overbuild above. This is especially an issue for us at night and in storms. Can you help?

Q: We have received some pushback from clients when setting up transmission pulling on EPZ mats that are constructed over crane mats, covered with galvanized cattle panels, overlapped, stapled down and bonded together. We follow a model passed down through our parent company’s safety research committee. Our clients have asked if the installation is certified. We did some research, found ASTM F2715 and are now wondering if that is what we should be doing. Can you help?

Q: Why do some experts say ground rods won’t work to trip a circuit? A: The experts say this because they are right depending on the conditions, which we’ll soon discuss. But let’s start with a definition of the idea of “remote ground” as the point at which we connect a protective system to earth. The lower the resistance of that remote ground connection to earth, the more current flows and the faster a fault clears. So, what we should be doing as a rule is using the best available ground to remote earth. The problem is that we often overlook a key element in this debate, which is that the ground source is not what protects the worker. The ground path trips the circuit. Bonding the worker into the ground scheme – the path between the fau…

Q: We don’t provide self-rescue equipment for lone workers, but we recently heard that OSHA is requiring self-rescue equipment as part of the General Duty Clause. Are you familiar with this? A: This is a complex question, part of which might border on legal arguments. Incident Prevention relates legal opinions to our readers from case outcomes that we are familiar with, but in practice avoids rendering advice or opinions that may border on legal terms. The rescue requirements in the OSHA rules do not address self-rescue. Many employers address self-rescue in part based on their interpretation of the training requirements found in OSHA 29 CFR 1910.269(a)(2)(i)(B) because of the language that states, “… including applicable emergency proce…