Abstract: An expansion enclosure assembly includes a bottom surface having apertures formed therein. The bottom surface may be adapted for connection with a base enclosure. The base enclosure includes a generator inlet connector aperture. The expansion enclosure includes cooling fans, racks for insertion of electronic components, access panels for enabling a user to access an interior of the enclosure, fiber optic cables suitable for installation through the generator inlet connector aperture, telephone cables suitable for installation through the generator inlet connector aperture, electrical cables suitable for installation through the generator inlet connector aperture, and a battery backup unit. The fiber optic cables, the telephone cables, and electrical cables of the expansion enclosure may be inserted through the generator inlet connector aperture during mounting of the expansion enclosure on the base enclosure.