Since 1914, the National Electrical Safety Code has been a go-to standard for electric and telecom utility companies. The code is updated every five years. The 2023 edition, scheduled to be released on 1 August, becomes effective on 1 February.
The NESC updates better protect workers, the public, and facilities during the installation, operation, and maintenance of power and communications supplies. The revisions are designed to help the code remain relevant as new technologies start to be used and safer ways of working are discovered.
Edited and published by the IEEE Standards Association and approved by the American National Standards Institute, the NESC has contributed to major electrical safety codes in most U.S. states, territories, and military bases; the Caribbean; and other entities and countries throughout the world.
Not to be confused with the National Electrical Code, which primarily addresses indoor wiring of homes and businesses, the NESC focuses on the outdoor lines that connect to homes and businesses, the electric supply stations and telecommunications plants, and their overhead and below-ground structures.
Sections of the safety code cover electrical grounding, substations, overhead and underground power lines, and work practices.
Roles dependent on the NESC include:
- Utility company business leadership, operations management, engineering and line design, crew supervisors, and safety trainers.
- Providers of power, telecommunications, cable television, wireless services, and the Internet.
- Railroads, for their power and signaling systems.
- Manufacturers of electrical equipment and associated product testing agencies.
- Consultants and contractors that assist in the design and construction of utility lines and infrastructure.
- State and federal regulatory agencies that provide industry oversight.
What Are the Updates?
- New rules 190 through 195 cover photovoltaic generating stations.
- Rule 116c adds an exception for short lengths of insulated power cables and short-circuit protection if the situation involves fewer than 1,000 volts.
- Rule 320B has been revised to clarify separations that apply to communications and supply in different conduit systems.
- Table 410-4 is based on the latest arc flash testing on live-front transformers.
- Rule 092A adds an exception allowing protection, control, and safety battery systems to not be grounded.
- Rules 234 B1, C1, D1 were revised to better present vertical and horizontal wind clearances, and to coordinate requirements with the new Table 234-7.
- Rule 120A was revised to provide correction factors for clearances on higher elevations.
- Table 253-1 has been revised to reduce the load factor for fiber-reinforced polymer components under wire tension—including dead ends—for Grade C construction.
- Rule 410A now requires a specific radio-frequency safety program for employees who might be exposed.
Some long-standing sections have been made clearer. For tables that include both English and metric values, the inch-foot-pound system is followed by the corresponding metric values in parentheses.
Working groups of NESC subcommittees have been formed to investigate up-and-coming topics such as generating stations and fault-managed power system cables, which might be used for 5G networks.
Supplementing the code is the NESC Handbook, which includes commentary by contributors to help users improve their understanding of the code and how it might be applied. Topics include code changes and rules for installing and maintaining electric supply stations. The handbook also provides rules for the operation of electric supply and communications lines and equipment.