Marylebone H/O 1936-               part 4

ELECTRICAL SERVICES

The whole of the Electrical Services throughout the Building have been installed on the screwed welded conduit system with ironclad type switchgear. A three-phase four-wire, 415/240 volt supply has been brought into the Building, terminating in an Intake Chamber in the Basement allocated to the Supply Authorities, from which electricity is supplied to the Main Switch-room, also situated in the Basement, through duplicate main cables.

The Switch-room equipment comprises two incoming oil circuit breakers supplying power, heating and lighting ,bus-bar chambers having metal-clad switch fuse-gear mounted thereon, from which current is distributed to the various distribution centres. The whole of the incoming supply is metered in the Switch-room on the outgoing power, lighting and heating sections. From the Switch-room, main cables are run to the various rising main switchgear enclosures which are situated in convenient positions in the centre section of each half of the Building. These cable are run vertically through all floors of the Building and feed the various services on each Floor.

In the switch gear enclosures the whole of the metal-clad sub-main switchgear, distribution boards, etc., is mounted on angle iron framework supports.

The Offices and Works Sections of the Building are separately controlled, and lighting and power circuits have been installed in a manner to suit exactly the requirements of the Works and Offices layout, special attention being paid to the question of accessibility both as regards. control and individual points. All lights are switched on individual circuits or grouped in suck a manner to suit the Works requirements.

For an emergency or standby supply for lighting purposes, a storage battery is installed, with rectifier and trickle charging equipment. The emergency lighting service is controlled by an automatic contactor control unit which switches all emergency lighting over to the battery in the event of a failure on the main supply. Corridor and staircase lighting is incorporated in the emergency system, and also lights in various sections of the Works and Offices.

Special arrangements have been made to allow the secondary lighting system to be employed by the night watchman as a pilot service.

The Building is equipped with G.P.O. telephone, system, having a 100 line switchboard situated in a central position in the Building.

For inter-communication within the Building, a very complete 100 line automatic inter-house telephone system has been installed, representing the very latest development in automatic telephony, and includes a number of instruments installed with loudspeakers and special push button facilities for calling selected Departments, obviating the necessity of dialling. The system also permits of priority calls, conference and secretarial services.

For fire protection, besides the installations mentioned under Mechanical Services, a fire alarm system has been installed. When any fire alarm is put into operation, indication is immediately given by visible and audible signals in the Watchman's Office. The visible signals indicate from which point of the Building the fire alarm emanated. The installation also includes a system of signalling throughout the Building, operated from the Watchman's Office, which enables the whole of the Staff in the Building to be warned that a fire has occurred, and that the Building is to be vacated.

Electric clocks are installed throughout, on the impulse system. The master clock is situated in the Watchman's Office, operating the various out-station clocks in the Building.

A programme repeater installation is included in the clock system, to automatically operate bell signals in various sections of the Building on a pre-selected programme, to indicate to the occupants starting and stopping times of work. A special feature is incorporated to automatically cut out this service during weekends and holidays.

For the convenience of calling principal Members of the Staff who may be in different parts of the Building, a system of Staff Signals has been installed, in conjunction with the clock dials. The clock numerals are illuminated, and each executive has an allocated number on the clock dial. To call any particular person, instructions are given to the telephone operator to put out that person's call. The telephone operator switches on the selected circuit, and the particular numeral is then illuminated on the clock faces.

The Secretary's Office with the Clock used in the Signalling System

In addition to this Staff Signal System, other systems are installed for special inter-communicating signals between Departments.

The lighting system throughout has been designed to accommodate the detailed requirements of the Company, the Main Showroom being lighted by a daylight and luminous balustrade around the gallery. In certain internal rooms artificial. illuminated windows have been incorporated. Throughout the various rooms direct and indirect lighting schemes have been employed. The main facade of the Building is floodlit, while the main Ground Floor show windows are equipped with a multiple of lighting points to permit of any decorative feature required. Such circuits can be controlled either manually or by time switch.

The whole of the motive power for the Boiler House, air conditioning plant and Works Sections of the Building, is supplied by electric motors arranged with automatic push button control. In the Boiler House a central indicator panel is installed, upon which indicators are given regarding the, operation of the various motor driven units.

For the Works requirements as regards electrical services, motor generators and transformers have been installed, supplying various A.C. and D.C. voltages, to enable testing of the Works products to be carried out under actual operating conditions prevailing in the District or part of the country to which they are .to be dispatched

For the electro-plating, electro-typing, nickel-plating and cleaning processes necessary for the Works, four rectifiers have been installed, having outputs of 100 to 500 amperes, at 3 to 6 volts.

Marylebone H/O part 5