Kinematograph year book (1927)

Digest of Acts. 157 pole switch shall be fixed for each arc lamp so that the pressure may 02 cut off whilst recarboning is taking place. (c) Where two or more projectors are installed and a change-over switch is required, it shall, unless it be a double-pole switch having a secure " off " position, be in addition to and not in substitution for the above main switch. (d) All live parts of apparatus within five feet of the projector shall be shielded so that they cannot be accidentally touched. The covers of enclosed switches shall be of metal and, with the exception of change-over switches, shall be so constructed that the switch handle does not work through an open slot. Where live metal is exposed so that it may be touched, the floor within a radius of three feet from a point immediately below the live metal shall be covered with insulating material. (e) Within the enclosure the pressure of the supply between any two conductors or between any conductor and earth shall not at any time exceed 250 volts direct or 125 volts alternating for the projector circuit. Where the supply of alternating current is at a higher pressure, the pressure shall be reduced by means of a double-wound transformer. In the case of a stand-by or temporary supply from across the outer conductors of a direct-current 3-wire system exceeding 250 volts, the projector circuit shall be taken as a shunt across part of a resistance connected across the outer conductors of the supply, so that the pressure within the enclosure shall not at any time exceed 250 volts. (f) The projector motor circuit shall be controlled by a double-pole switch or hand-shield plug. The motor starter and its resistance may be within the enclosure, but these and all other parts of the circuit shall be protected so that no live metal can be inadvertently touched. (g) Fuses shall be protected by enclosure in covers or cabinets against scattering of hot metal and shall be mounted in carriers or holders, so constructed that the hand cannot inadvertently touch live metal and that the hand is protected from the flash should a fuse blow on the insertion of the carrier in the contacts. (h) The lamp or lamps for lighting the enclosure and the rewinding room shall not be connected to the safety lighting. (i) All metal work liable to become accidentally charged, including the projecting apparatus, shall be efficiently earthed. The size of the earth wires shall be in accordance with the requirements of the Wiring Rules of the Institution of Electrical Engineers. (j) The arc lamp adjusting handles shall be made of insulating material and shall be so constructed and arranged that the hand cannot inadvertently touch live metal. (k) An ammeter shall be provided in the projector circuit within the enclosure. (I) Resistances shall be so constructed and maintained that no coil, or other part shall at any time become unduly heated, (a) The framework, supports and enclosures of resistances shall be made entirely of fire-resisting material. * Resistances shall not be attached to wood work and shall, as far as possible, be kept away from any wood work. All wood work shall, where necessary, be effectively protected against overheating. The terminals of the resistances and the connecting cables shall not be placed above the resistance elements. Resistances placed where they are liable to be accidentally touched shall be efficiently guarded. (w) Resistances, in which more than two kilowatts are dissipated, shall bs placed outside the enclosure and in a room or place other than the rewinding room accessible only to the technical staff. Adequate precautions shall be taken against fire resulting therefrom. If within the building, the room or place shall not communicate directly with the auditorium. It shall be well (a) e.g., they should not become so heated that a piece of newspaper placed in contact with any part of the resistance would readily ignite.