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1948-49 Theatre Catalog, 7th Edition, Page 347 (334)

1948-49 Theatre Catalog, 7th Edition
1948-49 Theatre Catalog
1948-49 Theatre Catalog, 7th Edition, Page 347
Page 347

1948-49 Theatre Catalog, 7th Edition, Page 347

obvious that such installations are usually neglected by the service and main tenance men as they are difficult to reach and maintain.

Further caution should be taken by the electrical contractor in making the installation during the construction of the theatre. The dimmer apparatus is a relatively expensive piece of equipment and should be handled with care to insure that it is turned over to the owner in first class condition. Tarpaulin or covers of some kind should be placed over the apparatus when plastering is performed within the immediate area, and at all times whenever any chipping or cutting of concrete or masonry is apt to cause particles of dirt and dust to fall into the dimmer equipment.

The apparatus should be given a thorough cleaning and lubrication before placing it in operation. All the instruction sheets supplied by the dimmer manufacturer as well as the switchboard manufacturer should be carefully reviewed by the contractor to insure that all points and considerations included in the installation recommendations are carefully carried out. If the apparatus is installed prior to closing in the building, care should be taken to prevent the rusting of steel parts or the corrosion of electrical contacts that would affect

THE DIMMER BANK may he installed in any loit area which exists above the proiection booth with extended levers so arranged as to be easily ac

the operation of the apparatus. After the apparatus is connected to the various lighting circuits a careful check of these connections should be made and compared with the wiring diagrams furnished for the installation. Only too often improper connections will cause a dimmer to fail before the owner of the theatre has had a chance to use it.

The use of shunting controls to cut out the dimmer equipment in the event of panic presents a very important wiring problem. Many states require that means be provided to turn on the lights in the auditorium from one or more remote locations regardless of the condition or position of any dimmer equipment or circuit switches included in the lighting system. With either resistance or reactance type dimmer equipment, a simple single pole contactor connected across the dimmer terminals will cut out the dimmer and cause the connected lamp load to burn at full brilliancy. However, with the Autrastat type of dimmer equipment, this cannot be accomplished so easily. Because the Autrastat is connected directly across the line, the load connection must be removed from the dimmer and placed on the line by means of a single pole, double throw transfer switch or contactor. Otherwise, if the dimmer happens to be near the

"dim" position a direct short circuit can be made by attempting to shunt between the line and the load connections.

The proper wiring connections for the dimmer equipment are shown in the diagrams. It will be noted that the resistance type dimmer is shown connected in the neutral return of the branch circuits. The National Electric Code permits this type of connection and it is recommended by the dimmer manufacturer because any fault in the lighting circuit between the lamps and the dimmer will not cause the dimmer to burn out. However, if any means is provided on the dimmer itself to automatically open the circuit in the tidim" position, then the dimmer equipment must be connected in the hot leg as the Code does not permit opening the neutral returns of lighting circuits. '

The Autrastat dimmer should be connected between the main source of energy and the branch feeder to the lighting circuits. A third connection from the neutral of the system must also be made to this type of dimmer. This connection should have a capacity of approximately 40% to 50% of the maximum connected load on each dimmer. It will also be noted that circuit protective devices should be included in the panel board, both ahead of the Autrastat dim cessible to the projectionist during his normal duties. Such an installation preSents little problem but the loft area should be accessible.

1948-49 Theatre Catalog, 7th Edition, Page 347