Aging Electrical Grid Implications
Russ Owen, CUSP
March 22, 2023
American infrastructure is aging across a number of categories, from bridges and roads to wastewater and energy. More than 70% of U.S.’s grid transmission lines and power transformers are 25+ years old. The current electric grid was not developed with today's electrification needs in mind. And when the power goes out, it is more than an inconvenience: power outages are estimated to cost the U.S. economy $28-169 billion annually.1
To address current and future needs, the Department of Energy’s Transmission Facilitation Program has developed a new initiative, Building a Better Grid, that will expand transmission capacity through new and upgraded high-capacity transmission lines. Roughly $20 billion of investment has been allocated to rebuild and improve our nation's aging electric grid, which will bring larger systems with more capacity.2
Larger systems with greater capacity mean more power with higher amperages. This will affect fault calculations. Fault calculation, or determining the current flowing through circuit elements during abnormal conditions like short circuits, is important in electrical design and in worker protection.3 Fault calculation determines if the ratings of protective devices and cables are appropriate to handle the worst-case situation that an electrical system may encounter.
One of the key components in the fault calculation process is to determine the total impedance, which can be represented by an “X/R ratio” (the amount of reactance divided by the amount of resistance in a circuit). Locations in or near substations, generation and high-load areas usually have high X/R.4
Implications for electrical workers
What does this mean for workers doing the construction and maintenance of this equipment when using temporary grounds? If they are working in high-load areas, they must use devices that meet stringent standards. In locations with X/R greater than 1.8, using ground sets with an H rating from ASTM F855 is required as of the date of this writing.5
Table 2 within the American Society for Testing and Materials’ F855, Standard Specifications for Temporary Protective Grounds to Be Used on De-energized Electric Power Lines and Equipment, outlines the test requirements for grounding assemblies to be used with the higher currents and higher X/R ratios that may be encountered in the field. Higher-rated components, which have been tested to the requirements in Table 2, are identified with a H rating. The values in Table 2 represent an X/R ratio of 30 (90% asymmetry).
Ratings for your application should be checked and verified regularly to ensure section of proper equipment.
How we help
Honeywell Salisbury™ is committed to providing the highest level of worker safety in this ever-changing environment. We offer a broad selection of grounding clamps and accessories that are compliant with the latest standard, including H rated grounding.
Proper selection and use of personal protective grounding has saved many lives. Rely on Honeywell Salisbury™ for protective equipment designed to meet your 5H & 7H grounding applications.
This article is part of a series. Learn more here.
About the Author: Russ Owen, CUSP, served in the U.S. Military for 21 years, 13 of which were spent in the U.S. Army doing power generation and distribution, and 6 years in power distribution safety. Now he is a senior technical lead at Honeywell Salisbury and serves on ASTM International committees (formerly known as the American Society for Testing and Materials). His experience as a lineman gives him first-hand insight into how to make our products both high-quality and user friendly.
1 - https://infrastructurereportcard.org
2 - Department of Energy. (2022, May 10). Energy.gov. Retrieved from Department of Energy: https://www.energy.gov/articles
3 - https://myelectrical.com
4 - Phillips, J. (2005, April 15). X/R Ratio. Retrieved from Brainfiller: https://brainfiller.com
5 - ASTM International F855-20. (2020). F855-20. Standard Specifications for Temporary Protective Grounds to Be Used on De-energized Electric Power Lines and Equipment. American Society for Testing and Materials.