FDX 20 fibre-optic boxes for 19-inch rack mounting collect cable terminations at one point in a telecommunications cabinet. The 1U housing-44.45 mm high, 480 mm wide and 280 mm deep-is metal, powder-coated and fitted with a pull-out drawer that allows splicing without removing the box from the rack. A version with twelve modular sockets supports 24 fibres, while the version with twenty-four sockets supports 48 fibres, with the same housing dimensions. Protection is IP20, operating temperature is −40 °C to 85 °C with an installation temperature of 0 °C to 50 °C, ferrules are made of zirconia ceramic with diameters of 1.25 mm for LC connectors and 2.50 mm for SC, and connectors withstand at least 500 mating cycles.
The box forms the transition point between the field level-cables laid in the ground over distances of kilometres-and active network components such as switches, routers and converters. Cable strength-member fastening, a splice tray with holders and internal fibre routing maintain the bend radius throughout the optical path. The boxes are supplied complete: the 12-duplex version includes twelve adapters, twelve blanking plugs, 24 pigtails and two cassettes; the 24-duplex version includes twenty-four adapters, 48 pigtails and four cassettes. Both have four cable entries at the rear with two Pg16 glands and a 19-inch mounting kit. The operating-temperature range makes them suitable for unheated wayside cabinets-an application argument independent of approvals and easier to demonstrate than normative compliance.
The boxes are selected by connector type and fibre category. Supported connectors are LC in compact SFF format for the highest connection density, SC with push-pull locking and ST, each in versions for 12 or 24 duplex connections. Fibre categories include multimode OM1 with a 62.5 µm core, OM2 and OM4 with a 50 µm core, and single-mode OS2 with a 9 µm core and PC polish. Datasheets for the 19-inch versions confirm resistance to flame propagation and housing flammability class V0 according to UL 94; they do not cite a railway standard. Compliance with DIN EN 45545-2 for fire protection is explicitly declared in the product list for DIN-rail versions; for the 19-inch version, confirmation is provided by the manufacturer’s declaration for railway applications downloadable from the manufacturer’s shop for the specific catalogue number. The range is complemented by field-attachable connectors, 1 m patch cords in LC, SC and ST configurations, and bulk fibre-optic cables in loose-tube, breakout and zip-cord designs.
