Page:Incandescent electric lighting- A practical description of the Edison system.djvu/66

, through "Am-meters" which show the amount of current being delivered by each couple, while two other ammeters are arranged in the bus line to indicate the total amount of current flowing out to the lamps. Beyond the am-meters are placed what are known as "Changing Switches," by means of which either the positive or negative circuit may be broken at will, so as to make both outside wires of the system either positive or negative; the neutral wire serving in such a case, either as positive or negative according to the way the switches are thrown.

This arrangement of the wires is rarely brought about except in case of an accident disabling some of the engines or generators when the load on the wires is very light.

To their proper bus are connected the feeder wires enclosed in tubes, 1, 2, 3, 4, leading to the junction boxes similiarlysimilarly [sic] numbered. These feeder wires are connected with the equalizers before described; the neutral wires, however, being