110.12 Mechanical Execution of Work. Electrical equipment
shall be installed in a neat and workmanlike manner.
Informational Note: Accepted industry practices are described
in ANSI/NECA 1-2006, Standard Practices for
Good Workmanship in Electrical Contracting, and other
ANSI-approved installation standards.
(A) Unused Openings. Unused openings, other than those
intended for the operation of equipment, those intended for
mounting purposes, or those permitted as part of the design
for listed equipment, shall be closed to afford protection substantially
equivalent to the wall of the equipment. Where metallic
plugs or plates are used with nonmetallic enclosures,
they shall be recessed at least 6 mm (1⁄4 in.) from the outer
surface of the enclosure.
(B)Integrity of Electrical Equipment and Connections.
Internal parts of electrical equipment, including busbars,
wiring terminals, insulators, and other surfaces, shall not be
damaged or contaminated by foreign materials such as
paint, plaster, cleaners, abrasives, or corrosive residues.
There shall be no damaged parts that may adversely affect
safe operation or mechanical strength of the equipment
such as parts that are broken; bent; cut; or deteriorated by
corrosion, chemical action, or overheating.
