British Kinematography (1951)

loo BRITISH KINEMATOGRAPHY Vol. 18, No. 6 To reduce fire hazard it is also requ red that the apparatus shall not be installed in the I >veen a i eiling and the floor boards Transformers and choke coils arc to be of the fixed reactance type. This would appear to exclude discharge tube lighting when the dimming is .iii. cl iriation oi rea< tan< e. Su< h would rous restriction and it is thought thai as such means oi dimming has only recently 1) en perfected the requirement was drafted prior to the development. Almost certainly steps will be taken to remove this anomaly which lias arisen due to progress outpacing legislation. inflammable material which Is fluid at normal working temperatures is to be used for insulation purposes in any part of the discharge ipparatus. If the tubes are placed within reach of the public they must be protected so that if a tube is broken a live electrode cannot be touched. REGULATION 19 This regulation deals specifically with luminous discharge tube installations where the pressure between any two parts of the installation exceeds 650 volts (i.e. high voltage). When cables are installed in positions where they may be me< hanically damaged they are required to be armoured or suitably protected. It is to be noted that in this instance conduit is not considered to be suitable protection. Unarmoured lead cables must not be drawn into conduits except for short lengths passing through a wall or ind all metal, including such short lengths of conduit, must be earthed. All metal parts of the installation, including irmers, liable to be charged at high voltage in the event of a defect occurring are required to be earthed independently of the earthing path of the metal conduit or sheathing. This will undoubtedly necessitate an additional earthing con: being provided in the majority of neon and other high voltage installations. Tf the c haracteristi< s of the circuit are such that ir similar excess current devices are Ineffec lutomatic c ut-outs must be fitted even if the rated input is below 500 volt-amperes. This will affed m iny kinemas which have cold cathode lighting fittings installed in vestibules or oJ the input wattage, if the 50 volts cut-outs must be ed. It ha I een stated that at the present • manufactured suitable input below 500 watts, and for this reason exhibil to comply with this : ously, firemen's switches controlling outside high voltage ins have been required fixed on the ■ : the building. But now exterior switches mast Ik installed also for ntrol of any fixed interior installations. The I.E.E. Regulations require such provision only if the interior installations are run unattended, and it is difficult to understand why this extra safety precaution has been imposed on kinematograph theatres. Indeed, the requirement In no way enhaiKcs the safety of such premises because these c in uits are never left unattended and are always under the ready control of the staff. The transformer rating of a transportable selfcontained high tension luminous discharge tube unit must not exceed 100 volt-amperes and any luminous discharge tube installations running unattended within a building for any display or window lighting must be controlled by a conspicuous switch located at the main entrance of the building or, in exceptional circumstances, in any other position approved by the licensing authority. The foregoing two regulations dealing with discharge tube installations have been criticised as being excessive and far exceeding the precautionary standards which experience has shown to be adequate. It is true that they are more stringent than those of the Institution of Electrical Engineers, which have been designed to cover installations in more hazardous situations than kinemas. Indeed, the I.E.E. Regulations are adequate for installations in garages and other places where there is a likelihood of the apparatus operating in an atmosphere containing inflammable vapours. REGULATION 20 Deals with electrical apparatus which requires to be installed in separate rooms, from which the public are excluded. It requires that generating plant driven by gas, oil engine or other prime movers, main supply and main circuit transformers, shall be installed in enclosures not communicating directly with the auditorium or an exit way. The enclosures must be constructed so as to prevent the spread of fire. The main supply and main circuit switchgear is also required to be installed in an enclosure and the door kept locked if it communicates with the public parts of the premises. Some licensing authorities have endeavoured to go well beyond this requirement and have demanded intake rooms of fire-resisting construction with fire-resisting doors, etc., but experience has shown that the fire risk in intake rooms is negligible, especially when all switches, busbars, etc., are ironclad. The lighting in projection rooms, rewind rooms, film stores, is required to be by electricity supplied from sub-circuits separate from the general or safety lighting systems. Thus safety lighting is now permitted in the projection suite. It is, however, to be noted that the regulation does not require that the enclosure, etc., must be illuminated by the safety lighting, it being left entirely to the discretion of the exhibitor, who may, if he so wishes, now provide it in these