Incident Prevention Magazine

9 minutes reading time (1862 words)

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.

Q: One of our substation workers received a serious shock while making a ground lead to a 345-kV substation grid. The structure was a new dead-end structure on concrete columns, part of a substation expansion. The grid in question was not yet bonded to the grid on the existing energized operating side of the station. The new grid was already installed with a hole left open and grid connection lead coiled up in the hole for later attachment to the structure. After the structure was set on the column, our substation electrician kneeled, grabbed the cable and touched the structure, receiving a shock. We know that grids can become energized when breakers operate, but this grid was not connected to the energized side. Can you explain what happened?

A: You have provided some good information, but we want to be clear that our response to your question is an opinion based on our experience. First, it’s important to understand that in order to have current on a substation grid, it’s not required that a breaker operates or a fault condition occurs. It depends on how well the grid works and where you are with respect to any source of current being conducted to the grid. We have measured hundreds of amps of current flowing to a grid as a result of induction from the overhead conductor crossing a station, and this likely is the case here. It is more probable that the current causing the exposure was coming from the tower as opposed to the isolated grid. The tower sitting on a concrete column is somewhat isolated from earth by the resistance of the concrete. Certainly, the concrete is of higher resistance than the copper cable in the grid. It is likely that your electrician bridged a gap between the grounded grid and the isolated steel tower that had induction on it coming from the substation’s nearby 345-kV bus.

Q: We recently held our first informal conference with OSHA over a serious-level citation that we, the employer, felt was incorrect. We had never been cited before by OSHA, so the informal conference was new for us. We used the OSHA guides, including the CPL 002-00-159 Field Operations Manual, to prepare for the meeting. The local OSHA office’s assistant area director met us for the conference, listened to our argument and then said he would present our case to the area director for consideration. We didn’t think that was right, but we decided to go ahead and pay the fine after they reduced the citation to less than serious. We didn’t think this handling of the informal conference allowed us a fair hearing of our case. What are your thoughts?

A: Your question provides an opportunity to discuss several OSHA changes as well as enlighten others about the perils of dealing with OSHA. The agency has been good for workers, as statistics indicate, and Incident Prevention has continuously supported OSHA’s efforts toward a safer workplace. Still, employers need to recognize that OSHA is in the business of writing rules and prosecuting employers. And they are very good at it. That does not mean we need to fear OSHA, but it does mean we need to be properly prepared to deal with them. The first thing we noticed while reading your question is that you referred to an outdated field operations manual (FOM) that no longer represents OSHA’s policy. OSHA replaced CPL 002-00-159 with CPL 002-00-160 in August 2016. The lesson here is, make sure the rules and guides you use are the most up-to-date versions. The latest PDF version of the FOM has 17 chapters and 280 pages. The previous edition had 16 chapters and 380 pages. Keep in mind that OSHA documents may be amended or revoked at any time, so users should visit the agency’s website (www.osha.gov) to be sure they are referencing the most current versions. Knowing you have the latest version also applies to any adopted or recognized consensus standards you use in your defense.

There is a disclaimer at the beginning of every version of the FOM that precludes any enforcement of any provision of the FOM by any person or entity against the U.S. Department of Labor. So, the FOM is not law that can be enforced. It is produced for the benefit of government and clearly states in the disclaimer that “No duties, rights, or benefits, substantive or procedural, are created or implied by this manual.” Still, we were surprised to learn that an assistant area director conducted your informal conference. A thorough reading of part 7(II)(F) of the FOM indicates that the area director should have conducted the informal conference. That doesn’t mean OSHA was wrong, but we are not aware of any directives or interpretations that would suggest otherwise. We also reached out to several consultants associated with iP who deal with OSHA. They agreed that in their experience, informal conferences are held with area directors. The reason is that area directors are the only entity at an area office who can make changes to a citation. Our opinion is that if an assistant area director was an intermediary, the area director may not have received a thorough explanation of your workplace activity.

Usually after an informal conference, if the employer is not satisfied with the outcome, they have the opportunity to file a notice of contest with OSHA for a formal hearing before a magistrate. That is not mandatory – it is simply an action open to the employer. Be aware that the employer must file a request for an informal conference that must occur within 15 working days of receipt of the citation. If the informal conference is not satisfactory, the employer still must file a notice of contest within that same 15-day period or the employer loses the right to contest the action.

Q: We were recently cited by OSHA after a tree being felled by one of our tree trimmers was struck by another tree that barber-chaired and hit the employee, resulting in his hospitalization. The basis of the citation was improper qualification for a tree feller, even though he had been a tree trimmer for us for 12 years. What are the rules for qualification?

A: If the citation used the work classification “feller,” we would assume OSHA is basing the citation on the logging standard, 29 CFR 1910.266. Most utility safety managers recognize and comply with the tree-trimming section in the OSHA standard for utility employers of tree crews. Tree crews trim trees. Tree crews are covered by part (r) of 1910.269. If the crew is using gas-powered chainsaws, they also must comply with part (e) of the 1910.266 logging standard. If tree crews are taking trees to the ground, they may be covered by other standards contained in the logging standard. The problem here is that the tree-trimming standards of 1910.269(r) are about trimming of trees for right-of-way power-line clearance and the working conditions normally found in that type of work. Felling trees is not tree trimming; it usually is considered by OSHA to be logging.

In your question, you indicated the employee was injured by a tree that “barber-chaired.” That is a term used by tree fellers, the worker with the chainsaw who fells trees. For our readers who may not be familiar with the term, a barber-chair is the result of an improper application of an undercut and subsequent back cut. Instead of the tree falling toward the notch in a controlled fashion, the tree violently splits up its length as it begins to fall. The split tree often breaks at the cut and can blow out explosively along its length, becoming a hazard to anyone standing nearby.

Your description indicates felling was in process. If a worker is felling trees, the worker also is expected to be in compliance with the applicable section of the logging standard that regulates manual tree felling. At a minimum, those rules would include:

  • 1910.266(d)(1), "Personal protective equipment," which requires hearing protection, chaps, face shields and cut-protective boots or protectors.
  • 1910.266(d)(6), "Work areas," which includes requirements for spacing of personnel, observers, escape routes for fellers and clearances from trees being felled.
  • 1910.266(e), "Hand and portable powered tools,” which holds the requirements for chainsaws, permitted use, maintenance and operation.
  • 1910.266(h), "Tree harvesting," and 1910.266(h)(2), "Manual felling," which cover OSHA’s requirements for manual felling of trees.

Do you have a question regarding best practices, work procedures or other utility safety-related topics? If so, please send your inquiries directly to This email address is being protected from spambots. You need JavaScript enabled to view it.. Questions submitted are reviewed and answered by the iP editorial advisory board and other subject matter experts.

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Friday, 25 May 2018

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