Almost every contemporary server rack cabinet dimension is based on one of the earliest, but still fundamental: AT&T's 1922 relay rack specifications. The dimensions are a 19-inch (482. 45 mm) rack height / module. A 19-inch rack is a standardized frame or enclosure for mounting multiple electronic equipment modules. Tapped - Front and Rear Flange. These are our most popular sizes! Hammond offers many more Relay Racks varying in size, material and. This report offers proven specifications, field-proven sizing data, enclosure structural standards referenced by EIA-310, ASHRAE TIA and NEMA, so you can forge your knowledge-based purchasing decision. 3 cm) (two- or four-post EIA cabinet or rack, with mounting rails that conform to English universal hole spacing per section 1 of ANSI/EIA-310-D-1992).