do not slide but are hinged two side lobes 52 are pivoted at 54 to the main central body portion 56 which mounts the base 58 the ballast is preferably divided into two parts each part being housed in a respective one of the side lobes as indicated at 60 in fig6 the two pivotal side lobes are swung up over the threshold 62 of the tube mounting socket of the adaptor fig4 illustrates how compactly the ballast can be configured at least in planform in the plane orthogonal to the axis of the threaded base its profile or planform is scarcely larger than the top portion of the mounting socket with a profile this compact the unit can be installed in most places previously using an incandescent bulb of course there must be adequate room to expand the lobes into the operational position shown in fig5 so that the fluorescent tube 64 can be installed in fig6 a parabolic reflector lamp is shown to make the point that the wide expanding portion of the reflector will fit between the two expanded lobes the fluorescent tube has a hot spot which is indicated at 66 in fig6 inside the mounting base of the tube fixture the hot spot corresponds to the location of the electrodes inside the ends of the tube it is very important to ventilate the portions of the tube around the hot spot as well as possible for this.