90.7 Examination of Equipment for Safety.For specific items of equipment and materials referred to
in this Code, examinations for safety made under standard
conditions provide a basis for approval where the record
is made generally available through promulgation by
organizations properly equipped and qualified for
experimental testing, inspections of the run of goods at
factories, and service-value determination through field
inspections. This avoids the necessity for repetition of
examinations by different examiners, frequently with
inadequate facilities for such work, and the confusion that
would result from conflicting reports on the suitability of
devices and materials examined for a given purpose.
It is the intent of this Code that factory-installed internal
wiring or the construction of equipment need not be
inspected at the time of installation of the equipment,
except to detect alterations or damage, if the equipment
has been listed by a qualified electrical testing laboratory
that is recognized as having the facilities described in the
preceding paragraph and that requires suitability for
installation in accordance with this Code.