Page:Incandescent electric lighting- A practical description of the Edison system.djvu/58

 the mains. The feeders are brought ia at such points as are best arranged for distributing the current equally throughout the mains.

In Fig. 14, the junction-boxes are numbered 1, 2, 3, 4, and the lines running from them to the station are the feeders. In addition to the three feeders, there Are three Pressure- Wires returning to the station, these latter being connected to what are termed "Pressure Indicators" located in the station in plain view of the operators.

These pressure indicators show the pressure at the ends of the feeders in the junction-boxes where they are connected to the mains, and warn the attendant when the pressure in any part of the system is either higher or lower than it should be.

Where wires are to be laid underground they are first carefully wrapped with an insulating material, and are then arranged in lengths of wrought-iron tube, which are afterwards filled with an insulating compound to prevent all contact