Abstract: A high power lighting device comprises a low voltage lamp which is driven from a mains supply via a toroidal transformer. The toroidal transformer 32 is housed radially outside of the reflector 20 of the low voltage lamp 10 in an annular chamber defined by a portion of a housing 12 and by a partition wall 46. The partition wall 46 is spaced from the low voltage lamp 10 and from the toroidal transformer 32 so as to form two coaxial airflow channels 48 and 50. Heat radiated from the low voltage lamp 10 is picked up by the partition wall 46 and air entering through suitably disposed openings at the front side of the lighting device flows through the two air channels 48 and 50, over both sides of the partition wall 46, and leaves the housing through openings adjacent the threaded base 18. The threaded base 18 and the shape of the lighting device make it possible for the lighting device to be screwed into normal threaded lamp sockets used for pressed glass type lamps.