October 2017 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 criteria for arc flash protection – excavation in a substation would not produce the type of work exposure you described that could create an arc flash. The location of the work and the type of work would not bring a worker within any distance of an energized bus or apparatus that would be a threat. If that’s the case, there would not be a requirement for arc-rated clothing for civil workers in a substation.
We are aware that there are utilities that require all workers, no matter what their craft or task is, to wear arc flash protective shirts while in a substation because it’s a company policy. But in regard to your question, it’s all about exposure. No exposure, no requirement for shirts. It is obvious that it’s not quite that simple for policymakers and risk analysts, who often are the people who make these decisions. Utilities must decide how to protect employees, protect the company and comply with the standards. That goal sometimes results in a blanket requirement as opposed to writing detailed criteria for when workers must suit up. The rules held by some utilities raise this question: If workers must wear arc-rated shirts, why don’t they have to wear arc-rated face protection? In fact, most of the inquiries we’ve made would seem to indicate the decision to require arc protective clothing in substations is more about gut response to the spirit of arc flash protection for contractors and employees than the result of arc flash analysis. Processes and knowledge are still expanding in the industry. As most would say, it doesn’t hurt for civil workers to wear arc protective shirts unless there is an unacceptable heat stress factor involved. In fact, there are some pretty lightweight pullover tees in Cat 2 that may help relieve both arc flash and heat stress.
It still is important to realize that arc flash shirts are not a solution in themselves. The real solution also requires training and supervision. Since all persons who enter a substation should have a level of training and qualification commensurate to the work they are going to do, it would be appropriate to “procedure out” any risks associated with arc flash exposure and then provide observation and supervision, making sure the procedures are in place. By “procedure out any risks,” we mean to establish work practices, pathways and access that minimize worker approach or proximity to energized facilities.
Q: We have relay technicians who occasionally enter substations to read or check electronic relays in reclosers. We train all employees who enter a substation and require them to meet certain criteria to be permitted to enter. The new MAD rules got us discussing whether a technician standing in front of a breaker would be required to wear rubber gloves or even hang a barrier between himself and terminals on the breaker. The reason is that we have determined that from the technician’s position, they often can reach up into the MAD. Do you have any advice?
A: There is no doubt that there is both exposure and risk, but they are minimized by procedures and training. As to training, as mentioned in the earlier answer regarding the civil workers, relay technicians are no different. The employer should be qualifying every person who enters a substation to the expectations of 1910.269(a)(2)(i) through (a)(2)(ii)(E), including the note at the end of that section. The employer also must ensure they know the risks associated with the work they do and the environment they are working in.
OSHA interprets and formulates the outcome-based rules of the 1910.269 standard from a practical viewpoint, understanding that the work must get done and that some safety practices would do more to raise risks than mitigate them. The technician opening the compartment where no primary voltages exist need not don Class 2 gloves simply because 15 kV is 8 feet above at his workplace. Placing barriers or cover would constitute more risk than any risk from standing at the recloser. The technician’s work does not require reaching for the bus, contact with the bus or entering the MAD for the 15-kV bus. Training and procedures will require observation of conditions before the technician approaches the recloser and then constrain the worker’s exposure to the relay cabinet. As long as workers follow those procedural constraints, any risk should be extremely limited.
Q: Our safety committee is having trouble determining what to do for servicemen and troublemen who typically work alone but have been checking voltage on aerial transformers. They are in reach of the primary bushings. Should they be covering them, should they be in primary class gloves and should there be an observer present?
A: We have recently received several questions regarding the more unusual conditions of exposure to energized systems and protecting employees while conforming to the OSHA rules. This situation is no less important. The good thing about this question is that we have an interpretation by OSHA that follows advice we have given in the past. We believe the answer is no, provided the employer trains on appropriate procedures to ensure safety of the worker. For the most part, we would interpret the OSHA rule based on the keyword “exposure.”
Rule 1910.269(l)(2)(i) states that at least two employees shall be present while any employees perform the following types of work:
- Installation, removal or repair of equipment, such as transformers, capacitors and regulators, if an employee is exposed to contact with parts energized at more than 600 volts. (269(l)(2)(i)(C))
- Work involving the use of mechanical equipment, other than insulated aerial lifts, near parts energized at more than 600 volts. (269(l)(2)(i)(D))
- Other work that exposes an employee to electrical hazards greater than, or equal to, the electrical hazards posed by operations listed specifically in paragraphs 1910.269(l)(2)(i)(A) through (l)(2)(i)(D). (269(l)(2)(i)(E))
Many utilities use the designation “service work” to differentiate levels of exposure, so we will start there. Service work often involves a lone worker. The OSHA standard addresses the two-worker issue for work above 600 volts without specifically establishing a rule or exception. The discussion leaves the determination up to the employer, who must be able to justify the safety of an exception so that a serviceman or troubleman can approach the front of an energized transformer for the purpose of checking voltage. The employer should thoroughly read the preamble discussion to clearly understand OSHA’s basis for interpreting the requirements for the rule. You can read the two-man rule discussion on pages 20417 through 20420 of the OSHA final rule published April 11, 2014, in the Federal Register, Vol. 79, No. 70 (see www.gpo.gov/fdsys/pkg/FR-2014-04-11/pdf/2013-29579.pdf). In the text, OSHA declined to specifically address a two-worker rule for under 600 volts, saying that even though the incident rate for injuries was very low, the lack of a detailed record could not justify addressing any voltage-specific exceptions.
For OSHA, the MAD issue, as well as the two-man issue, is, as always, based on exposure. Exposures are mitigated by procedures, engineering design, barriers or PPE. Approaching the front of an aerial transformer does put the user within 26 inches of the primary bushing if they are positioned face-high with the secondary bushings. If an enforceable procedure ensured approach to the secondary was reaching up from lower than the secondary bushings, the reach is outside the MAD.
The other option is to cover the bushing, thereby removing the exposure. But covering the bushing puts the worker in a greater exposure during covering than is involved with simply checking voltage. Some utility interpretations preclude covering the bushing, opting for the approach from below as sufficient, because they believe that covering the bushing puts the operator at unnecessary risk. If the operator can’t reach into the MAD from his work position, covering the bushing is of little value compared to risk of installing the cover.
Using these practices to check voltage, with the operator in Class 0 gloves and below the secondary bushings, he can’t make primary contact. In this case, an observer would not be required, strictly based on the criteria for an observer found in the rule. On the other hand, if the operator were handling a service and wires and could reach into the MAD, or pulling a service to a pole with secondary service leads sticking out past the dead-end device, the operator would be at risk of contact if the leads could extend into the MAD at the primary bushing. That exposure is criteria requiring an observer. The best practice is to tape the leads back to the service, limiting that exposure.
Getting back to the interpretation by OSHA, the agency agrees that from a work position limiting the reach and access to the primary bushings, a worker alone would not be in violation of the two-man rule. However, in that interpretation, OSHA left open the possibility that two men could be required if during approach or maneuvering to the work location, criteria for two men were established. You can read the interpretation at www.osha.gov/pls/oshaweb/owadisp.show_document?p_table=INTERPRETATIONS&p_id=27809.
Q: Pad-mounted transformers and switchgear sit out in the open, accessible to the public, but the new rules require utility workers to wear rubber gloves while handling them, including when unlocking them. What’s the difference between the risk to utility workers and the risk to the public?
A: There isn’t really much risk to the public if pad-mounted equipment is conscientiously installed by skilled professionals – no more than with pole bonds or down guys. The risk to utility workers is greater for two reasons: what is going on under that cover and what can happen when we move the cover. Those things can cause arcs or flashes that momentarily energize the tank or door; that’s long enough to seriously injure or kill a worker touching it. If you are one of those workers who comes into contact with pad-mounted equipment, you might do so thousands of times over your career. Doing so increases the chances you will be one of those the pad flash happens to, and you will be glad if you are gloved up.
As to the rules, there is no direct rule or statutory requirement we are aware of that transformers be opened with rubber gloves. There are the ET&D Partnership best practices that some think are OSHA rules, and for some contractors they are under particular conditions. You can read about the partnership at www.powerlinesafety.org. The Electrical Transmission and Distribution Construction Contractors, the IBEW and trade associations adopted the lock-to-lock rule to counter the argument that you can’t see what’s going on inside the pad when it’s closed. They instituted gloves, sleeves and arc wear to open the pad until you know the conditions. Those rules only apply to partnership employers and are not OSHA rules. However, if you are a partnership employer that has trained your employees to the published standard, and an employee is injured in an incident investigated by OSHA, you could be cited for a General Duty Clause violation for failing to employ a safe work practice recognized and/or known to the employer that would have protected the employee from injury.
As far as live-front switching and elbow switching, there is an exposure at the open end of the elbow while the elbow is moving. That open-end exposure would be no different than switching in a live-front. However, since it is handled by an insulated stick, it is outside MAD. Concerning arc flash exposure in live-fronts, according to the NESC design for enclosed primary cabinets at primary voltage, there is supposed to be an insulating panel or “second door” (see IEEE C2 381G) in front of the high-side when the exterior door is open. Technically that would be a barrier, so there is no exposure. Under these conditions, one man would be acceptable under the OSHA rules.
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underground, Worksite Safety, Q & A