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passing between the lamps, as shown at C. This is termed the neutral wire, and serves to conduct the current to either lamp of a couple when the other is turned out. Supposing the neutral wire to be of the same size as the other two wires, we then have in the three-wire system, three wires, each one half the size of any one of the four wires used in the two-wire system, thus we have for the same number of lamps but three eighths of the original amount of wire.
In actual practice this is further reduced by making the neutral wire one half the size of the other two; thus giving us a total of five sixteenths only of the wire used in the arrangement shown at A.
Fig. 12 shows very clearly the arrangement of dynamos, wires, and lamps, in the three-wire system. A and B are the dynamos; the positive wire r of A and negative wire t of B, forming the positive and negative wires of the system, while the negative wire of A, and the positive wire at B, unite at s to the neutral wire
