Publication: The Electrical Engineer
New York, NY, United States
THE MCDONALD GLASS HANGER BOARD.
THE insulation of appliances used in high tension series arc lighting is always of the greatest importance, and particularly for inside are light wiring where a dangerous voltage is carried into the building and directly to the lamp. A large number of arc light hanger boards have been designed from time to time, having for their object better insulation, and, for a newcomer, the McDonald glass hanger, are now claimed the most striking results. As shown in the accompanying illustration, the hanger board consists of glass insulating knobs mounted on a glass base or support. This secures a perfect insulation, which will always remain the same, as moisture or corrosion is not possible. This hanger makes a bright, clean appearance, and can always be kept in that condition. The extra holes shown in the base, allow the board to be used with three insulators, as shown; or with
only two insulators, one at each end of the board. When a series of lamps is being hung, the board at the end of the series may be used with two insulators, while all the other boards should be used with three insulators. Thus, when the wire readies the first board it is tied to the first of the two insulators at the double end. From this point a loop is made for the lamp, and the line wire leaves from the other insulator on the double end. This is repeated on each board of the series, until the last board having only two insulators is reached. On this board the line goes first to the insulator at one end of the board, then through the lamp to the insulator at the other end. From this point it starts back out of the building, using as support the free insulators on all of the boards having three insulating knobs. This makes a neat arrangement of the loops and at the same time a perfect insulation of both wires. The McDonald glass hanger board is being placed on the market by the Electric Appliance Company, of Chicago.