December 2019-January 2020 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 had no issues. There are others that had no issues for decades – right up until the day someone on their crew was injured by current on a static.
It’s not actually grounding that protects the worker; it’s bonding of the grounded static. Because of the hazard level associated with this discussion, we need to post a disclaimer here: Incident Prevention magazine publishes what it believes to be the best, most accurate advice available from industry experts, but the publication is not a training venue nor is it in the consulting business. It is the employer who is solely responsible for work methods employed in the field.
With that said, you are right: The static is grounded on most circuits, although we have seen insulated statics that are only grounded every three to five structures – or more – apart. Grounding a static has two principal functions. The first is that it serves as an overhead lightning shield. The grounded static is much more likely to be struck by ground-potential-seeking lightning than a phase conductor. As to the second function, grounding collapses the voltage that would be present on the static that could arc across hangers and clips and cause loss of the static into the phases. The voltage is a result of capacitive coupled induction of the energized phases below the static. With respect to lineworker safety, grounding the static collapses voltage on the static conductor, but it has no effect on magnetic or inductive coupled current on the static. Because the static is grounded at multiple points, each set of grounds creates a loop for current to flow. That means there are current loops all across a multi-grounded static. Multiple grounds keep the currents low, but on older systems that may have numerous broken ground connections, the current rise across the multiple spans of static can be very high. If you are connecting or reconnecting statics to pole bonds, you could be making a very high-current connection. In addition, there could be – and most likely will be – a significant voltage difference between the static that is grounded at adjacent structures and the grounded pole bond you are connecting to. There are several considerations and work methods appropriate when working a static.
Our contributors agreed that, if accessible, an insulated bucket with rubber gloves is a good approach, maintaining the minimum approach distance for the phases below the bucket. However, whether from an insulated platform, a crane basket or the structure, bonding with hot sticks between static and pole bond is required before glove contact to reduce risk of electrical shock from different potentials, as well as connection flash during the reconnect/repair. Use a short mechanical jumper or grounding jumper to mach out the broken bond connection before contacting it. You can get a current reading off the static using an AC amp meter to see how much current you are going to be shunting to ground when you make the reconnect. You also can use an auto-ranging AC voltmeter or phasing meter to check for potential between a static and a pole bond/ground connection.
Several of Incident Prevention’s consulting contributors have seen pretty high currents (induction) on older lines due to failed bond connections on circuits. High current on a grounded static can still cause a large connection flash in the worst case. Where there are numerous failed connections being restored, the first few repairs on a circuit will result in some big arcs until several connections are repaired, lowering the available current across the static.
Q: OSHA, the Department of Transportation and some other agencies require the employer to keep training records. Their rules also establish a set length of time to keep the records, but we can’t find any reference as to how long we must keep safety training records for the training required in OSHA 29 CFR 1910.269(a)(2). Can you help?
A: You should keep the records forever. That might be a bit of an exaggeration, but you must keep them for as long as an employee works for you. Here’s why: The rules don’t require you to keep records, but they do require that you be able to show that the employee has demonstrated the safety skills required in 1910.269(a)(2). That requirement can only be met if you have some kind of record to show that the employee was trained and evaluated.
Part 3-10 of OSHA’s Field Operations Manual (see www.osha.gov/sites/default/files/enforcement/directives/CPL_02-00-163_1.pdf) denotes the procedures a compliance officer follows during an investigation of a work site incident, referred to by OSHA as an “inspection.” Wherever you read an instruction about reviewing “documents,” you should insert “training records.” That’s because both 1910.269 and 1926 Subpart V – the horizontal standards that specifically refer to the utility industry – require training and the employer’s assurance of the employee’s demonstrated safety-related work procedures.
See Note 1 to 1910.269(a)(2)(viii), which states, “Though they are not required by this paragraph, employment records that indicate that an employee has successfully completed the required training are one way of keeping track of when an employee has demonstrated proficiency.” Utility and utility contractor employers who have had an OSHA inspection will tell you that the first documents OSHA asked them for were tailboards and training records for every crew member on the incident site. This note does not make any mandatory requirements, but there is no way to show compliance with 1910.269(a)(2) without some defensible form of documentation.
Q: Our company requires every employee to go through the OSHA 10-hour safety training. Some employees are familiar with what they refer to as the “T&D 10.” I have been unable to find a provider. Can you shed any light on this?
A: Sure. The OSHA 10-hour course you refer to as the T&D 10 is a specific curriculum for OSHA 10 that was established through the Electrical Transmission & Distribution (ET&D) Partnership. You can read more about the partnership at www.neca-neis.org/powerlinesafety.
The ET&D curriculum for the 10-hour training was developed with OSHA for the members of the ET&D OSHA/contractor partnership. Partnership members are the only ones required to undergo the training, and originally, they were the only ones authorized to deliver the ET&D OSHA 10 training and certify OSHA 10 cards with the ET&D Partnership logo.
However, there also is a resource from Georgia Tech. If you visit the school’s Professional Education website at https://pe.gatech.edu/sites/pe.gatech.edu/files/Mkg-LPs/OSHA/osha_catalog.pdf, you can find their 2019-2020 course catalog, which includes course EST 7020, “Electrical Transmission and Distribution: 10-Hour Construction Safety and Health.” It is our understanding that the Georgia Tech program offers the ET&D course and a completion card with the ET&D logo.
Q: We are looking for information about whether or not we have to wear an arc flash shield while completing normal switching operations on dead-front URD transformers. What is your opinion, or do you know the ruling on wearing an arc flash shield in this situation? We are having a hard time finding any information regarding if or when an arc flash shield is needed while completing this task.
A: Do you mean face shields or stick-mounted shields? We will address both. There is an abundance of information available in Appendix E to OSHA’s 1910.269 standard, titled “Protection From Flames and Electric Arcs,” including some exposure tables created by OSHA using the ARCPRO arc flash estimating program. We will try to summarize the information here but encourage readers to study Appendix E.
In dead-front switching, shields typically are not necessary because you do switching with hot sticks. Keep in mind that most arc flash calculations – including the OSHA tables in Appendix E for non-calculated exposures – are based on 15-inch clearance from arc source to worker in open-air and uninsulated systems. Even for uninsulated systems, when using sticks, the temperature of the arc exposure drops off exponentially the farther you are from the source. If you are 5 to 7 feet from the switch, the heat exposure is very low. You likely can find some people in your organization who have had switching go wrong and didn’t have any burn exposures. There also is a difference between dead front and live front in that dead front almost always contains the arc flash. From a practical perspective, we also must consider arc-in-a-box reflection of heat. That’s where policies such as clearances in front of equipment and length of sticks also have a protective effect for the employee. It still boils down to calculations, procedures and training.
As far as OSHA is concerned, there is no general requirement for shields except when the worker’s face is at or within the exposure boundary. You will find specific arc protective wear, including face shields above 8 cal/cm2, listed in the Appendix E tables. Shields for sticks are not mentioned by OSHA at all, including in the alternative exposure tables. Stick shields utilized by some utilities in switching have a purpose, but they are a choice to go above the standards. We get questions on where to find the requirements for stick-mounted shields from time to time. Those shields are another example of someone asking a question and a manufacturer creating a solution. From there, that “solution” creates a perceived need, and the next thing you know, everybody thinks you have to have one. That’s not the case.
The employer’s responsibility under the standard is to use either calculations or tables to estimate heat energy exposures and then equip the employee with the necessary arc flash protection. There is nothing wrong with using shields, but most calculated or table switching exposures as described above would not benefit from adding a shield. From practical experience, shields that are not required get in the way, especially in URD, and they are difficult to manage. Shields mounted on sticks have the same problem. When we inquired with our consultants, we found that some utilities supplied and installed stick-mounted shields, and that it started out well, but within a few months they were quietly removed and never used again.
By the way, where shields are required by analysis, the inconvenience of their use is not an excuse for not using them.
Q: We have an underground riser feeding a transformer. Both the riser and the transformer are going to be abandoned and removed. We opened the riser feed, removed the stingers from the disconnects and prevented backfeed at the transformer. Are we required by 1910.269(d) to get a clearance, and are we required to tag at either of the locations? Based on 1910.269, I am trying to understand if – when we isolate or create a way in which the wire can’t be energized – we still have to tag open points.
A: I think I understand your question, so my answer is no, you are not required by any OSHA rule to tag the switch in the scenario you described. If you are using 1910.269(d), “Hazardous energy control (lockout/tagout) procedures,” you will have a hard time figuring out what to do, but that’s because the section only applies to generation. Your scenario – and, in fact, all other transmission and distribution field switching and clearances – falls under 1910.269(m), “Deenergizing lines and equipment for employee protection.” Your specific question falls under a local control, 1910.269(m)(2)(iii), that OSHA considers safe since it’s operated by the qualified persons working behind the switch, who have ultimate control over the switch and/or stingers and the work process.
Paragraph 1910.269(m)(2)(iii) specifically states the following: “If only one crew will be working on the lines or equipment and if the means of disconnection is accessible and visible to, and under the sole control of, the employee in charge of the clearance, paragraphs (m)(3)(i), (m)(3)(iii), and (m)(3)(v) of this section do not apply. Additionally, the employer does not need to use the tags required by the remaining provisions of paragraph (m)(3) of this section.”
The only reason you would be obligated to tag is if your local utility procedures required it.
Do you have a question regarding best practices, work procedures or other utility safety-related topics? If so, please send your inquiries directly to [email protected]. Questions submitted are reviewed and answered by the iP editorial advisory board and other subject matter experts.