When it comes to personal protective grounding, it’s critical to go beyond just installing temporary grounds. Instead, you must integrate an entire process into the procedures to create safe working conditions. The workers can then go hands-on the lines and equipment while they are de-energized.
During my career working for a utility, I had a lot of experience with personal grounds. In fact, I helped to write the procedures as a line supervisor for overhead transmission and distribution and distribution underground. Today, as a consultant, I work with utilities to help them to write their own policies and procedures for grounding for workers’ protection.
To provide the current best practices, it is incumbent upon me to interact with the companies’ linemen, supervisors and engineers, and research the most recent findings related to working on lines and equipment in a de-energized condition.
To develop and implement personal grounding procedures, it’s important to work with the stakeholders at your utility. For example, the stakeholders include the employees who will be performing the work and the system engineers who will be providing the information about the fault currents, system protection equipment and devices. In addition, you should involve system operators and dispatchers whose responsibilities are to constantly monitor the status of the grid, and to retain or release control of circuits to the line crews. Other stakeholders include design engineers, the department responsible for purchasing equipment and drawing the construction standards, and the accounting team that determines from where the money is coming.
You also should review the changes to the construction standards, because new infrastructure will be purchased to enhance worker protection. For example, utilities are purchasing pull boxes with grounding lugs attached to the rebar in the concrete to create an equipotential zone when working on underground cable. In addition, distribution automation changes the way that workers clear equipment. As such, your training department must update existing materials and curriculum, and you should schedule all of the workers for training.
When developing procedures, particularly about personal protective grounding, consider several factors:
• Existing company procedures: Where are they? Who updates them and makes revisions? Are there multiple procedures that might conflict with each other?
• Conditions and climate the company works in
• Reviews of all construction standards
• Equipment and meters
• Training records
• Lockout/tagout procedures
• System operations procedures and policies
• Engineering specifications.
Creating a Plan
1. Set up a meeting. The first order of business is to get an on-site meeting with the individuals who will be committee members. These individuals will have the authority to review and sign off on the procedures and will be able to purchase test meters, equipment and other devices necessary for the work. Other key member are the system engineers as well as a system operator.
2. Review existing procedures. Be on the lookout for any conflicts. For example, a utility might have several procedures that mention the installation of grounds such as line work procedures, the safety manual or substation procedures. Some companies may have no procedures and instead rely on FED-OSHA 1910.269 or state guidelines. Although 1910.269 does not provide procedures for work, it does provide guidelines and conditions that the employer must implement for OSHA compliance so the employees can work safely on the lines while de-energized. Also, check to see if one set of procedures was recently updated and if there was a review of the other procedures to reflect the newest information.
3. Consider the system configuration. Does the utility run a wye or delta system? I’ve worked on ungrounded wye systems, multi-grounded wye systems, some delta and underground
systems that were non-jacketed and direct-buried (which creates an entire set of challenges for implementing personal protective grounding).
4. Take into account the conditions and the climate. When working in a rocky region, you have different issues to consider than if you are working in the desert or on the coast or an island. For example, what might work well in an area with a high moisture level may not work at all in one with low to no moisture. For example, I’ve installed grounds in areas where the resistance level is high enough that the system protection doesn’t activate.
5. Inspect the equipment and meters. Does the utility have all the necessary meters for testing de-energized to checking the resistance levels on the temporary ground rods that were driven into the earth? How about cable identification in dead front pad mount or subsurface equipment? Is there an ability to identify cable in trenches or boxes where there are multiple circuits?
Putting the Process in Motion
After you have done your research, work with the system engineers to create fault duty tables, then insert them into the document so the workers can reference the fault current to the grounding equipment. That way, they can ensure that the grounds can withstand an accidental re-energization of the lines without failing, long enough to trip the system protection.
Training, training and more training is necessary anytime your utility decides to install new equipment, devices and components such as distribution automation.
Also, when it comes to clearances and authorizations, it’s always preferable to move from a written clearance to an electronic one. This becomes especially important during mutual-assistance operations. You must review your company’s policies during storm response and determine which procedures have authority, both when you send your crews to assist and when you bring other crews onto your property to assist you.
In addition, you must consider which method is more effective, isolating or installing grounds. Recently, I was talking to a line supervisor about his company’s procedures, and he asked me whether he should install grounds or use an isolation method in a network system in a large metropolitan city. His challenge was the inability to get a visual open and test the cables because the switchgear was completely immersed in oil.
In summary, installing the grounds is not the total solution. In fact, the grounds are the last component in the total scheme of worker protection for working on de-energized lines and equipment. ♦
Maximo Fuentes retired as the Grid Assets T&D Line Supervisor-Business Operations for the Sacramento Municipal Utility District in Sacramento, California. He now owns a consulting business, Grid Resources, which provides technical consulting, leadership development and expert witness services to the transmission and distribution utility industry. Fuentes is also a general business partner for West Coast Utility Solutions – North.
Check out the May 2018 issue for more articles, news and commentary.