Continued from the February column, let’s resume our overview of the significant changes in the 2023 National Electrical Code.

New articles and revised titles

In addition to the articles discussed previously, one article has been added, while two others have revised titles to reflect scope changes.

• 725—Class 2 and Class 3 Power-Limited Circuits (Revised title). The title was revised due to the relocation of Class 1 circuits to the new Article 724.

• 726—Class 4 (CL4) Power Systems (New). This new article covers the installation of fault-managed power systems. Fault-managed power is defined as “A powering system that monitors for faults and controls power current delivered to ensure fault energy is limited.”

• 810—Antenna Systems (Revised title). The title of this article was changed to reflect the scope. It does not cover radio and television equipment and only covers antenna systems.

Article 100

In the January column, I mentioned significant changes to NEC Article 100 for the 2023 edition. The most significant change is that Article 100 will be the collection point for all definitions in the NEC. Furthermore, Article 100 will no longer be subdivided into parts. Part II applied only to definitions for installations over 1,000V. There were only five major definitions with some sub-definitions. Part III only applied to hazardous locations. Retaining it as a separate part would not work at this point, and would likely result in the call for many more parts.

After the first draft stage, there were more than 800 definitions in Article 100. Some will disappear because there was some duplication among the panels. Going into the second draft stage, there were some efforts to harmonize definitions among panels. Some new ones were added and some were deleted. Some terms were changed in favor of others that were more descriptive.

Definitions in the NEC receive more attention than they do in other NFPA documents, which explains why there are so many and why there are many revisions each cycle. Some are due to changes in technology that may combine functions of existing equipment, and others may be because an old definition doesn’t match what the equipment will do today.

Rules for definitions

The NEC Style Manual requirements are found in 2.2.2. The most important fundamental requirement is found in the NEC Style Manual as follows:

“2.2.2.2 Style. Definitions shall be in alphabetical order and shall not contain the term that is being defined. Definitions shall not contain requirements or recommendations.”

Let’s break that rule down. The requirement for alphabetical order makes perfect sense. However, I authorized breaking that rule in the case of the following set of definitions:

Dwelling, One-Family: A building that consists solely of one dwelling unit.

Dwelling, Two-Family: A building that consists solely of two dwelling units.

Dwelling, Multifamily: A building that contains three or more dwelling units.

Which one would appear first alphabetically? Dwelling, Multifamily. This drives the editorial purists nuts, but this violation of the rules made sense to me. It followed a different order (1, 2, 3+). It is unlikely to survive in the 2023 Code, however, and I am not sure that it should.

The next question about this definition is, does it violate the second part of the rule about using the term in the definition? No. “Dwelling unit” is a defined term, as follows: “A single unit, providing complete and independent living facilities for one or more persons, including permanent provisions for living, sleeping, cooking, and sanitation.”

Using the defined term in these other definitions makes more sense than trying to use the definition of dwelling unit together with the terms one, two or three or more. Why do we have to define all three? There are requirements that only apply to one- and two-family dwellings. Without a definition, would a two-family dwelling be considered a multifamily dwelling? Perhaps.

The final part of the rule for definitions is that they are not permitted to contain recommendations or requirements. These three definitions clearly do not, but some have issues every cycle. It is challenging to avoid requirements or recommendations in definitions, so the correlating committee is always on the lookout. Problem words in definitions include should, shall, must, may, listed and identified. Dimensions can also be a problem.

Let’s look at another definition. Is it a violation of the rule against requirements and recommendations?

Combustible dust: Solid particles that are 500 micrometers or smaller (i.e., material passing a U.S. No. 35 Standard Sieve, as defined in ASTM E11-17, Standard Specification for Woven Wire Test Sieve Cloth and Test Sieves) that can form a potentially explosive mixture when suspended in air at standard atmospheric pressure and temperature.

No. If the particles are larger, it isn’t a dust. It doesn’t recommend or require that anything be done to the particle. The reference in the middle of the definition is a violation of the NEC Style Manual. However, this definition is extracted from NFPA 499, Recommended Practice for the Classification of Combustible Dusts and of Hazardous (Classified) Locations for Electrical Installations in Chemical Process Areas.

There is a slightly new format for definitions. Most are straightforward and will appear as they always have. However, some require special treatment. The following is an example of a definition that required application of all of the unique format rules:

Hazard current, fault (Fault hazard current): The hazard current of a given isolated power system with all devices connected except the line isolation monitor. [99:3.3.72.1] (517) (CMP-15).

The term is displayed as “Hazard current, fault” and then parenthetically as “(Fault hazard current).” People subscribe to the electronic products because it is easy to search for terms. Displaying the term in its natural format aids in electronic searches. Otherwise, it might not be found by an electronic search of Article 100.

There are several numbers following the definition. The numbers [99:3.3.72.1] indicate this is an extracted definition originating in NFPA 99, Health Care Facilities Code. In most other NFPA documents, the definitions are numbered. This definition appears in Chapter 3 of NFPA 99 and is numbered as 3.3.72.1. The “(517)” means this definition only applies within Article 517. “(CMP-15)” indicates that Code-making Panel (CMP) 15 is responsible for the definition. However, because this is an extracted definition, CMP-15 can only make changes to the definition through the NFPA 99 committee, which means that the source document needs to be changed first.

Much of what appears in this example does not appear for every term. Some terms do not need to be rearranged for searches because their normal alphabetical order is how they are used in the Code. Most terms are not extracted from another NFPA standard, so that block of numbers will not appear. Most NEC definitions apply throughout the Code; therefore, it will be unnecessary to apply an article number parenthetically following the definition. All definitions will have a CMP assigned, so that will appear for every definition.

One final rule for definitions originates in the NFPA Manual of Style: the term must be used in the document. In my earlier days at NFPA, I served as the secretary/staff liaison for another committee in addition to the NEC. I found that there were several defined terms that were not used anywhere in the document. Some thought they were helpful, but they served no purpose in the application of the document, so they were deleted.

Specific Code changes

Here are the first Article 100 changes.

Accessible (as applied to wiring methods). Revised to recognize that accessible wiring methods are also those that are not “blocked by the structure, other electrical equipment, or building systems.”

Attachment fitting, weight supporting (WSAF) and its companion definition Ceiling receptacle, weight supporting (WSCR). These definitions replaced the terms “attachment fitting” and “locking support and mounting receptacle,” which first appeared in the 2020 Code .