Improvements relating to fluorescent lighting fittings

1,112,425. Cooling discharge lamps. ASSOCIATED ELECTRICAL INDUSTRIES Ltd. 23 Aug., 1965 [25 Aug., 1964], No. 34711/64. Heading H1D. [Also in Division F4] In a sealable casing consisting of a support member 4, e.g. of sheet metal, and a transparent cover member 5 and enclosing one or more fluorescent discharge lamps 1, 2, a duct 6 extends through but is sealed from the interior of the enclosure and has open ends, one of which in use is higher than the other, a thermal conduction path of solid material being provided between the interior of the duct and a selected portion of the lamp envelope to convey heat from the envelope to the interior of the duct. The cooling reduces the mercury vapour pressure inside the tube to the optimum value for operation. The duct may be of metal, e.g. copper or aluminium, or of plastics material. In the latter case a metallic element in contact with the envelope may project into the duct. The conduction path may consist of resilient metal clips supporting the lamp at the selected point or points, the clips being carried by a collar 11 forming a thickened part of the wall of the duct. Alternatively, when the duct 6 is of metal its outer surface may be in direct contact with the lamp.