December 2016 Q&A
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 devices used by employees to open circuits under load conditions are designed to interrupt the current involved.” There are some utilities that prohibit operating HLCs energized, and there’s nothing wrong with that. Our purpose at iP is not to judge an employer’s operational rules but to enlighten and educate the industry.
On its face, the rule seems to prohibit use of an HLC to break load. Anybody could also argue, then, that any operation of an HLC must be dead-break since HLC manufacturers offer no load-break value at all. However, there are several facets to analyze in this scenario. First, if a non-rated HLC cannot be lifted under load, how about a drop-out switch? We operate those thousands of times a day without injury to the employee, although sometimes an ill-advised operation does smoke a pole top. There is nothing in the rules that prohibits an employer from making an engineering-based decision establishing criteria or protocols for operating HLCs or drop-outs under certain load conditions. Primarily, the employer’s determination would be based on risk to the employee and risk to the equipment. For OSHA, the primary consideration would be risk to the employee. Just as in the working alone rule, if the device is operated by a hot stick from a position that prevented injury to the employee, there would be no violation. Second, what would be the solution in the scenario? If the solution required installing a mechanical jumper and installing a load-break switch, would such an operation add risk exposure to the crew, and would adding the switch really enhance the safety of the operation? At the very worst case, the scenario – operating the HLC under load – could be ruled a de minimis violation. De minimis is the level of violation where OSHA recognizes that a direct rule was violated, but there was no other way, or no safer way, of executing the required task, and there was no risk to the employee.
Q: It’s a common issue, so why doesn’t OSHA provide any guidance about setting up bucket trucks on slopes?
A: The first part of the answer is that OSHA doesn’t tell employers how to perform tasks. Though recent rule-making has occasionally leaned toward procedural expectations, historically the rules have been written to tell the employer what must be accomplished in certain scenarios as opposed to how we should accomplish tasks. Under the General Duty Clause, in absence of a specific rule, the employer is expected to ensure equipment is operated safely under all conceivable conditions in the workplace. The obvious place for the employer to gather information toward safe operation is from the manufacturer.
Regarding the use of tools and equipment, OSHA frequently makes reference throughout the rules to manufacturers’ design specifications. In any equipment incident, the first place OSHA compliance officers will go is the manufacturer. Employers may have competent engineers who make determinations, but an employer’s policy for setting up equipment should be strictly governed by the manufacturer’s operator’s manual. The manual will list maximum safe angle of slope and recommended orientation of the vehicle to the slope. It isn’t as common in utilities, but in construction many crews will have a dozer on-site and, if there are no environmental considerations, an operator can cut a flat on which to set-lift equipment.
Q: We recently had a discussion about whether to ground equipment operating in a substation. If the station rock bed is good, how much electrical isolation does it provide and can it be counted on as protection from step and touch?
A: Understanding the purpose of the rock bed and how grids are designed will give you a good basis for developing your safe work plans. The resistivity of crushed rock used in substations is about 3000Ω per meter. That crushed rock is part of a system of protection designed to conduct faults to earth, limit voltage rise across the station and control potential gradients across the surface of the earth inside the station. In one sense, the ground grid acts like a big equipotential blanket except that, unlike the blanket – which is a floating plane parallel connected to a conductive circuit – the substation grid is grounded at numerous points and is a series-conducting electrode passing voltage into the earth. The grid itself is designed both to meet grounding and fault-conducting duty and, in conjunction with the resistance of the earth, a plane of equipotential. Still, at the speed of light, there are instantaneous differences across the mat that can create voltage rises between any two points. The three functions mentioned are pretty much accomplished by the grounds and grid installed and the layer of compressed earth over the grid. The resistivity of the rock layer is just one more buffer layer designed to keep the voltage gradient at a tolerable level if a fault should occur in the station. The risk of step potential is dependent on a worker’s proximity to the source of the current and the magnitude of the fault. A well-designed system has very low resistance to earth. The isolating rock layer provides resistance between the grid and walking surface, further reducing voltage rise between a worker’s feet. The calculations for the design are complex and based on fairly reliable assumptions, as evidenced by the thousands of hours personnel spend in stations without incidents related to step potentials. However, grids do get damaged and rock does decompose and become contaminated. We cannot recommend using the rock layer as a principal means of protection since the rock layer cannot be tested to ensure it is isolating. The grid can protect against step potentials, but if your equipment comes in contact with an energized bus in the station, touch potentials between your truck and the grid still exist. Our recommendation is that you treat your equipment operating in the station just as you would in the field.
Q: We are a contractor that performs substation and transmission construction in several states in the eastern United States. Several of our clients are now asking us for our lockout/tagout program. We are exempt from LOTO in overhead lines, but what about the substations?
A: We are not actually exempt from the requirements for the control of hazardous energy. Part of the issue is simply the phrase “LOTO,” which is pretty foreign to the transmission and distribution side of the utility industry. OSHA’s 1910.269 standard has energy control requirements in parts (d) and (m) that are especially designed for the peculiarities of the industry, but that doesn’t mean we are exempt from 1910.147, “The control of hazardous energy (lockout/tagout),” common to all other industry. For all workplaces, there is a basic requirement that the employer has to perform analysis and create compliant workplace-specific activities to implement the control of hazardous energy. The transmission and distribution equipment in the field does not have lockable switches except where the switch mechanical or motor operators are at ground level.
In generation and substations, many devices are equipped and must meet the locking or tagging provisions of 1910.269(d), “Hazardous energy control (lockout/tagout) procedures.” Notice the words “lockout/tagout” in parentheses? Lastly, in the note to paragraph (d)(1), OSHA states the following: “Installations in electric power generation facilities that are not an integral part of, or inextricably commingled with, power generation processes or equipment are covered under §1910.147 and Subpart S of this part.” OSHA 1910.147 is the old general industry lockout/tagout standard, and Subpart S is the general industry electrical standard. In 1910.147 there is an appendix with the minimal requirements for a typical program. By the way, by most interpretations, those portions of the plant not inextricably linked to the generation of electricity are shops; warehouses; meeting, training and office spaces; and maintenance areas.
To recap, in all workplaces the employer has to identify those sources of energy that are a hazard and then provide the devices or means to isolate and control those sources. Once the hazards and methods of control are identified, the employer communicates the procedures and, if necessary, trains on how to install the control devices. If it can be locked out, it must have a lock installed unless the employer can ensure that tags only are an effective alternative. In the field, controls must be implemented such that the operations of the system and safeguards to protect employees are as effective as installing locks.
Do you have a question regarding best practices, work procedures or other utility safety-related topics? If so, please send your inquiries directly to firstname.lastname@example.org. Questions submitted are reviewed and answered by the iP editorial advisory board and other subject matter experts.