Figs. 786 to 789.—Various parallel systems. Fig. 786, cylindrical conductors parallel feeding; [fig. 787], tapering conductors parallel feeding; [fig. 788], cylindrical conductors anti-parallel feeding; [fig. 789], tapering conductors anti-parallel feeding. The term "tapering" is here used to denote a conductor made up of lengths of wire, each length smaller than the preceding length, the object of such arrangement being to avoid a waste of copper by progressively diminishing the size of wire so that the relation between circular rails and amperes is kept approximately constant. In an anti-parallel system, the current is fed to the lamp from opposite ends of the system.
Series-Parallel System.—This is a combination of the series and parallel systems, and is arranged as indicated in [fig. 790]. Several lamps are arranged in parallel to form a group, and a number of such sets are connected in series, as shown. It is not necessary for the groups to be identical, provided they are all adapted to take the same current in amperes, which should be kept constant, and provided the lamps of each set agree in voltage. For example, on the ordinary 10-ampere arc circuit, one group might consist of 5 lamps, each requiring 2 amperes at 50 volts; the next might be composed of 10 lamps, each taking 1 ampere at 100 volts, and so on.
Fig. 790.—Series-parallel system of distribution. It consists of groups of parallel connected receptive devices, the groups being arranged in the circuit in series.
Parallel-Series System.—In this method of connection, one or more groups of lamp are connected in series and the groups in parallel as shown in [fig. 791].
