16.) The location of the disconnecting means for Emergency Systems.
225.31 Disconnecting Means, 225.32 Location and 700.12 (B) (6) Outdoor Generator Sets
It is not uncommon to find a disconnecting means that has been improperly located for an Emergency System (Article 700) feeder which has been supplied from an outdoor housed generator. By the definition in Article 100 the conductors supplying an emergency system from a "separately derived system," in this case a generator, are considered as "feeder" conductors. Where the generator is located outdoors, the conductors would be considered as "outdoor feeder conductors" which are subject to the requirements of Article 225, Outdoor Feeders and Branch Circuits.
The scope of Article 225 (225.1) 225.31 states that a means shall be provided for disconnecting all ungrounded conductors that supply or pass through the building or structure. The first sentence of 225.32 requires the disconnecting means to be located either inside or outside of the building or structure served or where the conductors pass through the building or structure. The second sentence in this section notes that the disconnecting means must be at a readily accessible location nearest the point of entrance of the conductors.
The confusion typically comes in when the language in 700.12(B)(6) is applied improperly. This section, by the format of Code in 90.3, can supplement or amend Chapters One though Four. At first glance, one gets the impression that a disconnecting means that is located under or within the housing of an outdoor generator set can be used as the disconnecting means required by 225.31.
700.12(A) - (F) provide the general requirements for the acceptable sources of power supplying Emergency Systems. 700.12(B)(6) is titled "Outdoor generator sets" and states that "where an outdoor housed generator set is equipped with a readily accessible disconnecting means located within sight of the building or structure supplied, an additional disconnecting means shall not be required where ungrounded conductors serve or pass through the building or structure. One must further recognize that Article 100 defines the term "within sight of" and means that the specified equipment is visible and not more than 50' away. In the case of 700.12(B)(6), the "specified equipment" is the disconnecting means and it must be visible and not more than 50' away from the building served. The definition of "within sight of" in Article 100 does not preclude the use of a window in a panel of the generator housing. However, the disconnecting must be completely visible through the panel window from the building. On one final important note, 225.36 requires the disconnecting means to be suitable for use as service equipment and this requirement in not amended by Article 700.