I MOVABLE LIGHTING APPARATUS This invention relates to movable lighting apparatus. The invention has particular application to movable lighting apparatus of the type in which an array of lights is 5 mounted to a boom which can be raised when in a desired location for directing light onto a selected area and lowered for transport to another desired location. One known movable lighting apparatus includes a towable skid base with a vertically extendable boom with lights 10 mounted thereon, the boom being mounted so that it can be raised from a horizontal stowed position in which the boom is fully retracted and suitable for travel to a vertical position in which the -boom can be extended and suitable for operation. Such apparatus typically only provides for operation of the 15 lights when the boom is in the vertical position and only provides for securement of the boom in the retracted horizontal position or in a vertical position. The present invention is aimed at providing movable lighting apparatus which can be more easily moved from one 20 site to another and which provides for operation of the lights within a greater range of positions. With the foregoing in view, the present invention resides broadly in movable lighting apparatus, including: an elongate base having two spaced apart support members 25 adapted to rest on the ground and slide relative thereto during towing or pushing therealong and at least one connecting member connected to said support members to hold them in spaced apart relationship; a mounting post connected to said base towards one end 30 thereof for pivoting movement relative thereto about a vertical axis; a boom having a proximal end and a distal end and being mounted to said post at or adjacent its proximal end for pivoting up and down movement relative thereto about a cJON05114tIcdIOJunc2OI I 2 horizontal axis between a lowered position and a raised position and for pivoting movement about a vertical axis, said boom also being extendable from a retracted position to an extended position; 5 load bearing supports connected to said base for movement from a retracted position on or adjacent said base to an extended position remote from said base, said retractable load bearing supports being adapted to engage the ground when in the extended position to support said base; 10 drive means for extending and retracting said extendable boom, raising and lowering said boom about said horizontal axis, pivoting said boom about the vertical axis and extending and retracting said load bearing supports; lighting means operatively connected to said boom at or 15 adjacent its distal end; electricity generation means mounted on said base towards the other end from said mounting post and remote therefrom; and electricity communication means connecting said electricity 20 generation means to said lighting means. Preferably, said electricity communication means includes a cable drum mounted on said boom adjacent its proximal end, said cable drum being adapted to release and retract cable in synchronisation with extension and retraction of said boom. 25 Preferably, said cable drum includes a multi-point slip ring or similar device adapted to transfer electrical power theroacross irrespective of the angular position of said cable drum. In such form, it is preferred that said electrical communication means include a flexible cable extending from 30 said electricity generation means to said slip-ring with a predetermined amount of loose cable for accommodating movement of the cable drum as the boom is pivoted about the vertical and horizontal axes. Preferably, pivoting movement of the mounting post relative to the base about the vertical axis is cJONO5H14ti1ed1June2011 3 limited to less than a complete turn so that the cable from the generation means to the cable drum cannot be wound about the post. That is to say, the arrangement is such that the post can only rotate through less than 360 degrees about the 5 vertical axis in one angular direction or the other and preferably through less than about 330 degrees. In a more preferred form, the angle of rotation(or pivot) is less than about 60 degrees thereby ensuring greater stability when the boom is extended. 10 Preferably, said electricity generation means is a close coupled generation unit which includes an internal combustion engine and an alternator or generator coupled thereto. It is also preferred that said electricity generation means be mounted to said base such that its weight is spread across the 15 base as far as possible. It is also preferred that a fuel tank for the engine be mounted to the base between the generation unit and the mounting post. Preferably, said drive means includes an electric drive motor coupled to a hydraulic pump which in turn is drivingly 20 connected to hydraulic rams or motors suitably arranged to drive the boom as previously described. In such form, it is preferred that the electric motor be powered by the electricity generation means. In such form, it is preferred that the electricity generation means be selected to drive the 25 electric drive motor while powering the lighting means. It is also preferred that the drive means have a substantial hydraulic oil reservoir and that the drive means and the reservoir be mounted to said base close to said mounting post to provide weight thereat. 30 The terms "horizontal" and 'vertical" are intended to describe; the orientation of the particular axis or component being referred to when the apparatus is at rest on a level horizontal surface even though the axis or component may not be geometrically exactly vertical or horizontal. Further, such cJONO51 Iftilcd1OJUne2O1 : 4 terms are not intended to limit the apparatus to use in any particular orientation. In order that the invention may be more easily understood and put into practical effect, reference will now be made to 5 the accompanying drawings wherein: Fig. 1 is a perspective view of movable lighting apparatus according to the invention with the boom raised and fully extended; Fig. 2 is a side elevation of the apparatus of Fig. 1 with 10 the boom in the same position; Fig. 3 is a front elevation of the apparatus of Fig. 1 with the boom in the same position; Fig. 4 is a rear elevation of the apparatus of Fig. 1 Fig. 5 is a side elevation of the apparatus of Fig. 1 with 15 the boom lowered and retracted in the ready to move position; Fig. 6 is a plan of the apparatus of Fig. 1 with the boom lowered and retracted in the ready to move position; Fig. 7 is a side elevation of the apparatus of Fig. 1 showing the extent of boom movement to the front and rear in phantom; and 20 Fig. 8 is a plan of the apparatus as shown in Fig. 7 showing the extent of sideways boom movement in phantom. The lighting apparatus 10 illustrated in the drawings includes a base 11 having two spaced apart side rails 12 and 13 formed of steel channel with upwardly tapered front and 25 rear lead in end portions 12a, 13a and 12b 13b. Suitably, the side rails are connected by a plurality of spaced apart cross members shown typically at 14 and 15. Advantageously, a front bumper 16 and a rear bumper 17 extend upwards from the side rails and are welded thereto to provide means by which the 30 base can be pushed either forwards or backwards by a bulldozer or the like. A boom mounting post 18 is pivotally mounted to a mounting block 19 which in turn is fixed to the base 11, the post being arranged to pivot (or swivel) on the mounting block about a JONS1141Ikd0IJUne2011 5 vertical axis 21 and an extendable boom 22 is mounted to the post near its upper end for up and down pivoting movement relative thereto about a horizontal axis 23. A lighting frame also in known manner for apparatus of this type and driven by 5 a hydraulic motor (not visible in the drawings) . An extendable boom 21- is mounted to the turret for up and down movement about a horizontal pivot pin 22 also in known manner for apparatus of this type. A lighting frame 31 having an array of lights 32 mounted 10 thereon is connected to the distal end 33 of the boom by a pivot pin 34 for up and down movement relative to the boom and the pin can be locked in any selected predetermined position. The lights in the array are powered by a diesel engine driven generator unit 41 which is bolted to the base towards 15 the front end. Advantageously, the generator unit provides a suitable: counterweight for the boom and the lighting frame attached thereto when extended rearwards and also provides a suitable base weight for stability when extended in other directions. Suitably, a large fuel tank 42 is mounted on the 20 base beside the generator so as to add to the weight and act as a suitable counter weight. A power cable 51 extends from the generator unit 41 to a retractable cable drum 52 mounted at the proximal end of the boom and.is connected thereto via a slip ring so as to connect 25 to a cable 53 wound thereon so as to travel with the boom in unison with it extending and retracting and is connected to the lighting array at the distal end 54. Advantageously, a sensor is mounted on the drum to determine when the cable is fully unwound from the drum and the sensor in turn is 30 connected to a controller connected to the light activation switch (or the generator) so as to prevent the lights running while cable is still wound onto the drum. cJONOS i4filed IOehia20 I 6 In other forms of the apparatus, the cable is attached to the boom in a manner which allows it to loop thereunder as the boom is retracted. In such form, the drum is not required. Suitably, two opposed outrigger type load bearing support 5 units 61 and 62 are mounted to the base for stabilising the base when the boom is extended sideways. Advantageously, the support units are hydraulically operated and can be raised for travel or lowered to engage the ground remote from the base as required. In other forms where the boom is not required to 10 extend sideways, the outrigger load bearing supports can be omitted. An electric motor driven hydraulic pump and reservoir unit 43 is mounted on the base in front of the post 18 for supplying hydraulic fluid to drive the boom in and out and up 15 and down as well as the outriggers. In one embodiment, the spool is also hydraulically driven in which case the hydraulic pump also supplies fluid to the spool drive while in another embodiment the spool is electrically driven but in yet another it is cable driven by the boom as it extends and retracts. 20 In use, when temporary lighting is required at a particular location on a mining site, for example for machinery breakdown .repairs night mining etc, the lighting apparatus is towed or pushed to the desired location by a bulldozer or other suitable machine where the boom is fully extended and the 25 generator started to supply power to the lights and the lights turned on. The foregoing description has been given by way of .illustrative example of the invention and many modifications and variations which will be apparent to persons skilled in 30 the art may be made without departing from the spirit and scope of the invention as described herein. eJON05S 4filed1OJuine20I1