The National Electrical Safety Code (NESC) is published by the Institute of Electrical and Electronics Engineers (IEEE). The latest edition is designated as ANSI C2 2017. This article examines the basics of the NESC relative to its scope and purpose, provides essential information about correlation with the National Electrical Code (NEC) and addresses the importance of the term “service point.”
Section 015 of the NESC, “Intent,” provides information about mandatory text as compared to recommendations within the NESC. For example, the words “shall” or “shall not” indicate mandatory requirements while the words “should” or “recommendation” indicate nonmandatory requirements. Exceptions modify a rule’s minimum requirements. Within the NESC, examples and notes often provide further information. The recommendations, notes and exceptions follow the rule to which they apply. Recommendations are not included in the NEC, but exceptions and informational notes also follow the rule to which they apply.
The NESC’s purpose is to provide basic rules for safeguarding persons from hazards arising from the installation, operation or maintenance of conductors and equipment in electric supply stations, and both overhead and underground electric supply and communication lines. It also includes some work (safety in the workplace) rules for the construction, maintenance and operation of electric supply and communication lines and equipment. The NESC is generally applicable to systems and equipment operated by utilities. It also can apply to similar systems and equipment in an industrial establishment under the control of “qualified persons,” another term both codes define.
NESC rules are recognized and intended to provide a practical standard of safe practices that can be adopted by public utilities, private utilities, state or local utility commissions or public service commissions, or other applicable boards or bodies. NESC rules contain basic provisions, under specified conditions, considered necessary for the safeguarding of the public, utility workers (employees and contractors), and utility facilities. Just like the NEC, the NESC is not intended as a design specification or instruction manual.
The NESC scope provides specific details about what is covered and what is not. In general, the NESC covers installations on the supply side of the utility meter installed on the premises. That includes a lot of infrastructure such as power distribution systems, electrical transmission, substations and generation facilities.
The NESC and NEC both use the term “service point,” and it has the same definition and meaning between the codes. The definition is simply the point of connection between the facilities of the serving utility and the premises wiring. It is generally understood as the point of demarcation and between the serving utility and the premises wiring, clarifying applicability. Another way to look at it is the service point on the wiring system is where the serving utility wiring ends and the premises wiring begins.
The serving utility generally specifies the location of the service point based on the serving utility’s condition of service and applicable utility service requirements. If the conductors are located on the utility side of the service point, they are not covered by the NEC. The NEC clearly defines the terms “service lateral” and “service drop” as being covered by the utility, thus the NESC rules where it is so adopted. Based on the NEC definitions of “service point,” “service lateral” and “service drop,” any conductor on the serving utility side of the service point generally is not covered by the NEC. In contrast, the terms “overhead service conductors” and “underground service conductors” are covered by the NEC.
It is important to note that the location for a service point may vary between utilities and occupancies; in addition, locally adopted utility service requirements may apply. It is always a good practice to verify what code is adopted in a jurisdiction and determine if there are any local amendments that must be applied to an installation. This holds true on both the utility side and the premises wiring side of the established service point.
The 2022 NESC is currently in its development cycle, and more information can be found at standards.ieee.org/about/nesc/form.html. The NEC Correlating Committee has taken important steps to correlate where possible with the NESC main committee in areas of growth and common interest. The idea is to achieve appropriate coverage and correlation without conflict or duplication.
For example, a large-scale photovoltaic, wind or energy storage system installed and maintained under the exclusive control of a serving utility would not be covered by the NEC. In these cases, the applicable code should include the requirements for these installations or should provide users references between the codes. This keeps each code relevant, adoptable and enforceable.