by Mike Hyland, NESC and American Public Power Association
The 100-year-old National Electrical Safety Code (NESC) is not a design manual, but the code is leveraged widely in design criteria for power and communications distribution facilities throughout most of the U.S. and an increasing number of countries worldwide. Consequently, its impact on the finances of the utilities, telephone companies and wireless companies that look to the NESC in construction design can be substantial.
Although existing facilities are grandfathered, ongoing code changes in areas such as strength and loading can influence the financial costs of construction projects. A proposed change to the upcoming 2017 edition of the NESC that would remove a 60-foot exemption regarding extreme wind load is a prime example.
In the 1960s, storms brought down several hundred miles of transmission lines suspended on tall structures. The storm brought no ice, but bare wind loading on the lines was substantial because wind speed (and, thus, wind pressure) increases with height above ground. The experience eventually led to the addition of a new extreme wind loading map to the NESC in the 1977 edition of the code-with the stipulation that the extreme wind load case was not required if a structure or conductor was less than 60 feet above ground.
Today, however, with the use of even larger conductors and multitudes of large communications cables, taller poles are being installed, and bare wind loadings are leading to failures on electric distribution systems. As a result, one of the change proposals under consideration for the 2017 edition of the NESC is removal of the exemption and application of extreme wind loading to all structures, regardless of their height.
An open commentary period is going on now through May 1, 2015, on this and the other change proposals in line for the code. The input of utilities, telephone companies, wireless companies and other entities with so much financial stake in the NESC’s evolution is key to ensuring rollout of the best possible edition code for all stakeholders.
Utilities’ Stake in the NESC
In continuous use since its inception in 1914, the NESC proposes basic provisions that are considered necessary for the safety of employees and the public alike during installation, operation and maintenance of electric supply and communication lines and their associated equipment.
In varying degrees, nearly every state has adopted the NESC, and about 100 other countries use the code in some manner. Some states adopt only the construction and maintenance rules in the NESC, for example. Others do not adopt a safety code for utilities but refer to the NESC as issues crop up related to its scope. California, on the other hand, has its own state safety code but reviews its requirements in light of the new release of the NESC every five years.
The range of applications addressed in the NESC is sweeping: electric supply stations (generating facilities and substations), high-voltage transmission towers and joint-use poles for local distribution of communication and power services, underground systems and buried areas in easements and rights of way, among them. The code’s scope is from the point of generation (or delivery from another entity) to the “service point,” where power or communications systems are handed off to a customer’s premises wiring system.
Most NESC users are in the electric utility industry. This makes utilities’ stake in the NESC’s ongoing refinement especially critical. Beyond the financial stake, the safety of so many utility field technicians, contractors and customers can be affected by changes to the code.
Keeping the Code Up-to-Date
It is a never-ending and open effort to keep the NESC effective and relevant in the face of new technologies and challenges presented by population growth, mobile communications and Internet proliferation, the smart grid, etc.
As the standards and collaborative solutions arm of IEEE, the secretariat of the code since 1972, the IEEE Standards Association (IEEE-SA) oversees the open and inclusive process through which the code is revised methodically every five years.
The current 2012 edition of the code introduced key changes and clarifications in areas such as the NESC’s application regarding the National Electrical Code (NEC), techniques for effective grounding, protection of electrical supply stations, underground inspection rules and requirements, apparel arc ratings and minimum approach distances (MADs).
We are on our way to the next edition of the NESC. Since the 2012 edition was published, change proposals were received from the public and then considered by NESC subcommittees. We are amid an eight-month period of open commentary on the preprint of those proposed changes for the 2017 edition of the code. This period of open commentary is made intentionally wide so plenty of time is given for all voices to be heard. Until May 1, 2015, any interested party may review, affirm or suggest additional changes to the change proposals for the next NESC edition.
In addition to the proposed elimination of an existing exemption for structures and supported facilities not exceeding 60 feet in height from extreme wind and ice with concurrent wind loading rules, several of the proposed revisions being considered for the 2017 NESC also include:
- Definitions around communication equipment, electric supply equipment and structure conflict;
- Clearance rules regarding communication space above supply space; and
- Harmonization of the NESC’s work rules with Occupational Safety and Health Administration (OSHA) 29 CFR §1910.269 and §1926 Subpart V final rulings.
The complete NESC 2017 Preprint is publicly available at www.standards.ieee.org/store. Visit the NESC website, www.standards.ieee.org/about/nesc/erp/index.html, to understand more about how to participate in the ongoing open commentary period and submit your thoughts electronically. A wide range of inputs, expertise and lessons learned from the real-world field is sought.
After the open commentary, relevant NESC subcommittees will review the proposed revisions and comments. The draft of the next edition of the code will go before the NESC Main Committee for approval, as well as concurrent public review by the American National Standards Institute (ANSI), and, finally, ANSI’s Board of Standards Review. The 2017 edition of the NESC is scheduled to be published Aug. 1, 2016.
August 2014 marked the 100-year anniversary of the NESC. A century after the National Bureau of Standards initially brought together representatives of electric utilities, telephone utilities, railroads and factory owners to drive consistency and safety considerations into the design, construction and utilization of U.S. electricity and communications infrastructures, the code is one of the most widely adopted safety codes.
Protection of utility field employees, contractors, other workers and the public is the primary concern of everyone involved with the NESC’s evolution, but the financial implications of changes are important, too. As the code’s largest base of users, utilities’ stake in the NESC from every perspective is tremendous. Utilities should weigh in now on the 2017 edition of the code and ensure their input and requirements are reflected.
Mike Hyland is NESC chair and senior vice president of engineering services at the American Public Power Association (APPA).
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