On ten of the lines the number of wires is greater than three or four, thus reducing the necessary size of each wire for a given conductivity of the line. The Butte, Oakland, and Hamilton lines are run on two sets of poles for greater security, and a second pole line has been added to the Niagara and Buffalo system to carry additional wires.
The largest wire used in any of these lines is the aluminum cable of 500,000 circular mils between Niagara Falls and Buffalo. This cable has 1.66 times the area in cross section of a copper cable of equal conductivity.
SIZES AND MATERIALS OF WIRES ON SOME AMERICAN TRANSMISSION LINES.
+----------------------------+----+------+----------+--------+-------+ | | | | | |Length | | | |Number| Size of | | of | | Location of Transmission. |Line|Wires.| Each Wire|Metal in|Trans- | | | +-+ +--+ B. & S. | Wire. | mis- | | |Volt- | | Gauge. | | sion. | | |age. | | | |Miles. | +----------------------------+------+-+-------------+--------+-------+ |Cañon Ferry to Butte |50,000|6| 0 | Copper | 65 | |Colgate to Oakland |40,000|3| 00 | Copper |142 | | | |3| 000 |Aluminum|142 | |Electra to San Francisco |40,000|3|471,034 C. M.| „ |147 | |Santa Ana R. to Los Angeles |33,000|6| 1 | Copper | 83 | |Apple River to St. Paul |25,000|6| 2 | „ | 25 | |Welland Canal to Hamilton |22,500|3| 1 | „ | 35 | | | |3| 00 | „ | 37 | |Cañon City to Cripple Creek |20,000|3| 3 | „ | 23-1/2| |Madrid to Bland |20,000|6| 4 | „ | 32 | |White River to Dales |22,000|3| 6 | „ | 27 | |Ogden to Salt Lake City |16,000|6| 1 | „ | 36-1/2| |San Gabriel Cañon to Los | | | | | | | Angeles |16,000|6| 5 | „ | 23 | |To Victor, Col |12,600|3| 4 | „ | 8 | |Niagara Falls to Buffalo |22,000|6|350,000 C. M.| „ | 23 | | „ „ „ |22,000|3|500,000 C. M.|Aluminum| 20 | |Yadkin River to Salem |12,000|3| 1 | Copper | 14.5 | |Farmington Riv’r to Hartford|10,000|3|336,420 C. M.|Aluminum| 11 | |Wilbraham to Ludlow Mills |11,500|6|135,247 C. M.| „ | 4.5 | |Niagara Falls to Toronto |60,000|6|190,000 C. M.| Copper | 75 | +----------------------------+------+-+-------------+--------+-------+
Aluminum lines are now employed for the three longest electrical transmissions in North America. In the longest single line, that from Electra power-house to San Francisco, a distance of 147 miles, aluminum is the conductor used. The 142-mile transmission between Colgate and Oakland is carried out with three aluminum and three copper line wires. For the third transmission in point of length, that from Shawinigan Falls to Montreal, a distance of 85 miles, three aluminum conductors are employed.