110.12 Mechanical Execution of Work.

These requirements focus on the installation of electrical equipment.  Electrical installations must be neat, and care must be taken for various reasons.  The parent language of this section is clear in that electrical installations must be installed in a professional and skillful manner.

Section 110.12 includes 3 first level subdivisions as follows:

(A) Unused Openings

Openings in electrical equipment expose workers and others to energized parts.  Openings are placed in equipment to connect conduit, install wire, and allow for components to extend beyond the enclosure for access.  Enclosures must not expose energized parts.  When plugs or plates are used on nonmetallic enclosures that are metallic, special care must be taken to ensure this section is met in regard to being recessed from the outer surface of the enclosure.  The requirement is that it has to be ¼ in. from that outer surface.

(B) Integrity of Electrical Equipment and Connections

The overall integrity of electrical equipment and connections are important for electrical safety.  This section addresses the internal parts of electrical equipment such as busbars, wiring terminals, insulators and more.  These portions of the equipment are behind closed doors and their integrity is important especially when covers are removed during maintenance and other justified energized work. A review of these internal parts for paint over spray, plaster debris is important during the installation phase of a structure.  In addition, this section points out the fact that many cleaners and other methods that may be used to maintain equipment such as abrasives or other corrosive materials can jeopardize the integrity of the equipment.

In general, installed equipment must not be jeopardized due to contamination or damaged parts and pieces.  Review the installation realizing that all aspects of the equipment will come under stress especially when the system experiences a fault or other abnormal condition.  In addition, future electrical workers will be accessing this equipment and that access very well could be while energized.  The integrity of the equipment and connections is critical for their safety.

(C) Cables and Conductors

Sometimes, cables and conductors must be installed in such a manner that they are exposed on the surfaces of ceilings or sidewalls.  In these cases their integrity and protection is important as the only thing between an energized conductor and a person or other metal object that may cause a fault, is a relatively thin layer of insulation of varying materials.  This section seeks to ensure these conductors are supported by the building structure and secured such that they will not be damaged by normal building use. Two important sections to ensure are met include the following:

300.4 Protection Against Physical Damage

300.11 Securing and Supporting

A reference in this section is made to be considerate of the cable ties and other nonmetallic cable accessories that may be used in spaces that are used for environmental air.  This equipment must be listed as having low smoke and heat release properties.

NFPA 70-2023 Change

Changes were made in the parent text of 110.12 addressing the phrase “neat and workmanlike manner.”  To make this language gender neutral, this text was replaced with “professional and skillful manner.”Section 110.12(C) was modified to remove informational note No. 1.  The submitter of public input number 300 noted that inclusion of optical fiber cables in 110.12(C) is inappropriate.  Article 110 deals with electrical installations and optical fiber cable installations are not electrical.  This is already addressed in 770.24.