Tag: Q & A

August-September 2023 Q&A

Written by Jim Vaughn, CUSP on August 18, 2023. Posted in Q & A.

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...

June-July 2023 Q&A

Written by Jim Vaughn, CUSP on May 19, 2023. Posted in Q & A.

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...

August – September 2022 Q&A

Written by Jim Vaughn, CUSP on August 11, 2022. Posted in Q & A.

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...

April – May 2022 Q&A

Written by Jim Vaughn, CUSP on April 15, 2022. Posted in Worksite Safety, 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...

February – March 2022 Q&A

Written by Jim Vaughn, CUSP on February 24, 2022. Posted in Worksite Safety, Q & A.

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...

December 2021 – January 2022 Q&A

Written by Jim Vaughn, CUSP on December 13, 2021. Posted in Worksite Safety, Q & A.

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...

October-November 2021 Q&A

Written by Jim Vaughn, CUSP on October 4, 2021. Posted in Worksite Safety, Q & A.

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...

August-September 2021 Q&A

Written by Jim Vaughn, CUSP on August 11, 2021. Posted in Worksite Safety, Q & A.

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...

June-July 2021 Q&A

Written by Jim Vaughn, CUSP on May 21, 2021. Posted in Worksite Safety, Q & A.

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?

April-May 2021 Q&A

Written by Jim Vaughn, CUSP on April 15, 2021. Posted in Worksite Safety, Q & A.

Q: I read the article “A Practical Review of the ANSI A92.2 Standard” in the October-November 2020 issue of Incident Prevention magazine (see https://incident-prevention.com/blog/a-practical-review-of-the-ansi-a92-2-standard/), and I’d like to know, is there a standard for the construction of electrically insulating bucket liners? We have problems with the geometry of a bucket. Because the walls of the bucket and the bucket liner are separated, I need to know the tolerance or maximum distance between the walls of those elements. Can you help?

February-March 2021 Q&A

Written by Jim Vaughn, CUSP on February 12, 2021. Posted in Worksite Safety, Q & A.

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...

December 2020-January 2021 Q&A

Written by Jim Vaughn, CUSP on December 11, 2020. Posted in Worksite Safety, Q & A.

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...

October-November 2020 Q&A

Written by Jim Vaughn, CUSP on October 7, 2020. Posted in Worksite Safety, Q & A.

Q: We have a crew performing pole change-outs with the line energized. They are suspending phases with a link stick and digger derrick to provide more clearance between phases to install new poles and hardware. The question is, can the operator leave the controls with the phase lifted? We thought they could, but it seems there has been a change to OSHA 29 CFR 1926.1417(e). A: The good news is that you cited the wrong rule. Pole change-outs fall under the 1910.269 operation and maintenance rules. You cited the rule for construction (OSHA 1926). The operation and maintenance rule – found at...

August-September 2020 Q&A

Written by Jim Vaughn, CUSP on August 18, 2020. Posted in Worksite Safety, Q & A.

Q: I read what was written about an air gap for worker protection in the June-July 2020 issue of Incident Prevention magazine, but one of our engineers who sits on a National Electrical Safety Code advisory committee brought something to my attention. NESC C2-2017 444.2 states, “Air gaps created (e.g., cut or open jumpers) for de-energizing equipment or lines for the purpose of protecting employees shall be tagged and meet minimum clearances as specified in Table 444-1 or separated by a properly rated insulator.” What are your thoughts on this matter? A: Thanks for your question. Our...

June-July 2020 Q&A

Written by Jim Vaughn, CUSP on June 16, 2020. Posted in Worksite Safety, Q & A.

Q: Should we worry about beards in relation to arc flash? At our company, we think hair generally protects the body against extremes. Do you know of any evidence to the contrary? A: Here is what we know: Human hair is protein fiber. It will burn when exposed to a flame but stop burning when the heat source is removed. Human hair does not melt; it becomes a fragile ash that turns to powder when crushed. This property is known as self-extinguishing. Hair is pretty much like cotton – it burns away. As such, it is not a hazard related to arc flash and actually provides some protection. OSHA...

April-May 2020 Q&A

Written by Jim Vaughn, CUSP on April 13, 2020. Posted in Worksite Safety, Q & A.

Q: Recently we had an employee reference OSHA 29 CFR 1926.960(f) and 1910.269(l)(7), “Conductive articles.” The question is, can an employee work in an energized area while wearing jewelry, and earrings in particular? The rules discuss conductive articles such as watches, bands, rings and chains, but I do not see where it mentions earrings. A: When it comes to interpretation, it is good to confine a rule to the language used, but sometimes you also have to address the intent. The concern that drove the creation of this rule was whether jewelry, which is conductive, increases...

February-March 2020 Q&A

Written by Jim Vaughn, CUSP on February 19, 2020. Posted in Worksite Safety, Q & A.

Q: Where does OSHA’s switching and lockout/tagout policy draw the distinction between generating plants and the plants’ substations, particularly with metal-clad substations? A: It depends more on the equipment used than a distinct line, and it has to do with OSHA’s intent, equipment design and practicality. Let’s look at this from the perspective of intent. OSHA intends that employers have an energy control plan that protects workers. LOTO was developed for that and has worked very well over the years. The data shows that LOTO has been directly responsible for a dramatic decline in severe...

December 2019-January 2020 Q&A

Written by Jim Vaughn, CUSP on December 13, 2019. Posted in Worksite Safety, Q & A.

Q: As a contractor doing transmission maintenance, we see many different constructions of statics at the tops of transmission poles and structures. They’re grounded, and we always thought they were safe to handle with leather gloves. Now we’re hearing that statics should be grounded temporarily for worker protection. What’s the explanation for that? A: It’s called a “static,” but don’t forget that the voltage and current flowing on it is induction-coupled alternating current that will kill you. As an industry, there are a lot of utilities that have worked statics in leather gloves and have...

October-November 2019 Q&A

Written by Jim Vaughn, CUSP on September 16, 2019. Posted in Worksite Safety, 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...

August-September 2019 Q&A

Written by Jim Vaughn, CUSP on August 19, 2019. Posted in Worksite Safety, 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...

June-July 2019 Q&A

Written by Jim Vaughn, CUSP on June 14, 2019. Posted in Worksite Safety, 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...

April-May 2019 Q&A

Written by Jim Vaughn, CUSP on April 10, 2019. Posted in Worksite Safety, 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...

February-March 2019 Q&A

Written by Jim Vaughn, CUSP on February 18, 2019. Posted in Worksite Safety, 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...

December 2018-January 2019 Q&A

Written by Jim Vaughn, CUSP on December 14, 2018. Posted in Worksite Safety, 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...

October-November 2018 Q&A

Written by Jim Vaughn, CUSP on October 11, 2018. Posted in Worksite Safety, 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...

August-September 2018 Q&A

Written by Jim Vaughn, CUSP on August 10, 2018. Posted in Worksite Safety, 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,...

June-July 2018 Q&A

Written by Jim Vaughn, CUSP on June 12, 2018. Posted in Safety Management, Worksite Safety, Q & A, Grounding.

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),...

April-May 2018 Q&A

Written by Jim Vaughn, CUSP on April 18, 2018. Posted in Worksite Safety, 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...

February-March 2018 Q&A

Written by Jim Vaughn, CUSP on February 21, 2018. Posted in Worksite Safety, Q & A.

Editor’s Note: This installment of “Q&A” addresses some common questions Incident Prevention receives throughout the year. Most are misunderstandings of the wording or intent of OSHA standards. From time to time iP has addressed the following scenarios – or similar ones – because they never seem to go away. In the following answers, the research or interpretation methods employed have been summarized to help readers become more familiar with interpretation and construction of the standards. Q: Does OSHA 29 CFR 1910.269(l)(12), “Opening and closing circuits under load,” prohibit the use...

December 2017 Q&A

Written by Jim Vaughn, CUSP on December 15, 2017. Posted in Worksite Safety, Q & A.

Q: I understand OSHA has made a final announcement on minimum approach distances. Can you explain the latest information? A: On December 22, 2016, OSHA issued a memorandum to regional administrators regarding the enforcement of minimum approach distance requirements in 29 CFR 1910.269 and 1926 Subpart V (see www.osha.gov/pls/oshaweb/owadisp.show_document?p_table=INTERPRETATIONS&p_id=31079). The memorandum had an effective date of July 1, 2017. Readers will recall that concerns about the rising risks of transient over-voltages were the basis for the increased minimum approach distances...

October 2017 Q&A

Written by Jim Vaughn, CUSP on September 11, 2017. Posted in Worksite Safety, Q & A.

Q: We have gotten mixed advice from our colleagues at other utilities and can’t decide whether or not civil workers digging a foundation by hand in a hot substation should be required to wear arc protective clothing. They are inside the fence but in a new area approximately 20 feet from the nearest distribution structure. Where do we find the requirements or OSHA guidance? A: That depends. Sometimes it depends on the criteria in the statutes, and sometimes it depends on compliance with company policy. Normally, following the guidelines of OSHA 29 CFR 1910.269(l)(8) – which establish the...

August 2017 Q&A

Written by Jim Vaughn, CUSP on August 8, 2017. Posted in Safety Management, Worksite Safety, Q & A, Grounding.

Q: We are a contractor and were recently working in a manhole with live primary cables running through it. We were cited in an audit by a client’s safety team for not having our people in the manhole tied off to rescue lines. We had a tripod up and a winch ready for the three workers inside. What did we miss? A: This question has come up occasionally, and it’s usually a matter of misunderstanding the OSHA regulations. The latest revision of the rule has modified the language, but following is the relevant regulation. Look for the phrases “safe work practices,” “safe rescue” and “enclosed...

June 2017 Q&A

Written by Jim Vaughn, CUSP on June 7, 2017. Posted in Safety Management, Worksite Safety, Q & A, Equipment Operations, Grounding.

Q: We have a group reviewing our personal protective grounding procedures, and they are asking if we should be grinding the galvanized coating off towers when we install the phase grounding connections. What are your thoughts? A: In addition to your question, we also recently received another question about connecting to steel for bonding, so we’ll address both questions in this installment of the Q&A. Your question is about the effectiveness of grounding to towers, and the other question is about the effectiveness of EPZs created on steel towers. We’ll discuss the grounding question...

April 2017 Q&A

Written by Jim Vaughn, CUSP on April 18, 2017. Posted in Safety Management, Worksite Safety, Q & A.

Q: Our plant safety committee has a longtime rule requiring electrical hazard safety shoes for our electricians. We were recently told by an auditor that we have to pay for those shoes if we require employees to wear them. We found the OSHA rule requiring payment, but now we wonder if we are really required to use the shoes. Can you help us figure it out? A: Sure, we can help. But first, please note that Incident Prevention and the consultants who have reviewed this Q&A are not criticizing a rule or recommending a rule change for any employer. What we do in these pages is explain...

February 2017 Q&A

Written by Jim Vaughn, CUSP on February 15, 2017. Posted in Safety Management, Leadership Development, Worksite Safety, Q & A, Equipment Operations.

Q: We are a small, distribution-only municipal utility that has been looking into human performance. We are having some trouble understanding it all and how it could benefit us. Most of the training resources are pretty expensive. Can you help us sort it out? A: We can. Human performance management (HPM) has been around in various forms and focuses since before the 1950s. Throughout the ’50s and ’60s, it seems the focus was on companies performing functional analysis and correcting issues that created losses, thereby promoting more efficient and error-resistant operations. In the ’60s and...

December 2016 Q&A

Written by Jim Vaughn, CUSP on December 12, 2016. Posted in Safety Management, Worksite Safety, Q & A, Equipment Operations, Grounding.

Q: We hear lots of opinions on whether a lineworker can lift a hot-line clamp that has a load on it. There is a rule that says disconnects must be rated for the load they are to break. We’ve been doing it forever. Are we breaking an OSHA rule or not? A: Incident Prevention has answered this question before, but it won’t hurt to revisit it and use the opportunity to explain how OSHA analyzes a scenario to see if it’s a violation. Most objections to operating a hot-line clamp (HLC) under load are based on OSHA 29 CFR 1910.269(l)(12)(i), which states that the “employer shall ensure that...

October 2016 Q&A

Written by Jim Vaughn, CUSP on October 12, 2016. Posted in Safety Management, Worksite Safety, Q & A, Equipment Operations.

Q: What is meant by the phrase “circulating current” as it pertains to transmission towers? Does it have something to do with the fact that there is no neutral? A: We’re glad you asked the question because it gives us an opportunity to discuss one of the basic principles of the hazard of induction. More and more trainers are teaching with a focus on principles instead of procedures, and we often overlook some of these basic definitions. The concept of circulation is associated with what happens in any interconnected electrical system. Refer to the basic definition for parallel paths:...

August 2016 Q&A

Written by Jim Vaughn, CUSP on August 22, 2016. Posted in Safety Management, Worksite Safety, Q & A, Equipment Operations.

Q: We have heard that OSHA can cite an employer for violation of their own safety rules. How does that work? A: OSHA’s charge under the Occupational Safety and Health Act is the protection of employees in the workplace. The agency’s methodology has always assumed the employer knows – or should know – the hazards associated with the work being performed in the employer’s workplace because that work is the specialty of the employer. OSHA’s legal authority to use the employer’s own safety rules as a reason to cite the employer is found in CPL 02-00-159, the Field Operations Manual (FOM), which...

June 2016 Q&A

Written by Jim Vaughn, CUSP on June 10, 2016. Posted in Safety Management, Worksite Safety, Q & A, Equipment Operations, Grounding.

Q: Is a transmission tower leg considered a lower level? And is there an exception for hitting a lower level when someone is ascending in the bucket truck to the work area? Our concern is that the shock cord and lanyard could be long enough that the person could hit the truck if they fell out of the bucket prior to it being above 15 feet. A: The February 2015 settlement agreement between EEI and OSHA addresses both of your questions, which, by the way, were contentious for several years until this agreement. The settlement agreement includes Exhibit B (see...

April 2016 Q&A

Written by Jim Vaughn, CUSP on April 26, 2016. Posted in Safety Management, Worksite Safety, Q & A.

Q: What is an employer’s affirmative defense relative to an OSHA charge and how does it work? A: In simplified legal terms, an affirmative defense is the act of an accused party putting forth a set of alternative claims or facts. The purpose of the accused party doing this is to mitigate the claim against him, or at least the consequences of the claim, even if the facts of the claim are true. Following is an example of a fairly common scenario in which an affirmative defense is claimed by an employer. OSHA investigates an incident that resulted in an injury to an employee and finds the...

February 2016 Q&A

Written by Jim Vaughn, CUSP on February 12, 2016. Posted in Safety Management, Worksite Safety, Q & A, Grounding.

Q: I work for a small utility and am new to my safety role. Recently I have been wading through the Federal Motor Carrier Safety Regulations (FMCSR) in an attempt to understand my responsibilities with regard to testing CDL drivers. Can you briefly explain these responsibilities? A: FMCSR 391.31 requires the employer to ensure a driver is competent by means of road testing. The FMCSR allows a valid commercial driver’s license as evidence of competency (see FMCSR 391.33). If the employer accepts the evidence of the driver’s competency, the employer does not have to road test the driver. Rule...

December 2015 Q&A

Written by Jim Vaughn, CUSP on December 16, 2015. Posted in Safety Management, Worksite Safety, Q & A, Equipment Operations, Grounding.

Q: I’ve been reading ASTM 855, IEEE 1048 and the National Electrical Code, and I’m a little confused by the practice of grounding through a switch. Can you help me better understand this? A: In transmission/distribution applications, there is no issue with grounding through a switch. To explain, we always have to ask whether the issue is grounding through (in the path) a switch or grounding (by way of closing) a switch. The application may sound the same, but it depends on which standard you read. Our subject matter experts think the confusion lies in the well-known NEC rules, which require...

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Tag: Q & A