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STRANDS OF COPPER WIRE.

C С

OPPER WIRES are laid up into concentric strands

or into ropes of seven strands. A rope of seven strands each composed of seven wires, is called a seven by seven rope, and is usually written 7x7. The number of wires that can be made into a strand is limited hy the capacity of the stranding machinery. Two hundred wires is the usual limit of a concentric strand, and one hundred and thirty-three wires of a rope.

In a strand of circular milage, C. M., composed of n wires of diameter d, with a weight per 1 000 feet w, then we have

O. M.=d? x n.

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The weights of strands are calculated about one per cent. heavier than a solid wire of the same circular milage, while the resistance is calculated for the solid wire.

In specifying how a strand shall be made, the number of wires to be used or the diameter of each wire may

be given. In the first case the wire usually has to be specially drawn, and this will delay an order, especially a small order, unduly. It is, therefore, better to specify the size wires B. &. S. G., of which the strand is to be made.

The diameter of a strand may be calculated by multiplying the diameter of one wire by the factors given in the table at the bottom of the opposite page, according to the number of wires composing the strand.

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[blocks in formation]

377.

1 000 000 || 1 000.

288.7 229.4 192.5 164.4 144.3 128. 950 000 974.6 368.4 | 281.4 223.6 187.6 160.2 140.7 | 124.7 900 000 948.6 358.5 273.9 217.6 182.6 155.9 136.9 121.4 850 000 921.9 348.4 266.1 211.5 177.4 151.5 133.1 | 118. 800 000 894.4 338. 258.2 205. 172.1 | 147. 129.1 114.5

[blocks in formation]

750 000 700 000 650 000 600 000 550 000

866. 327.3 250. 198.6 166.7 142.3 125. 110.8 836.6 316.3 241.5 / 191.9 161. 137.5 120.8 107.1 806.2 304.7 | 232.7 | 184.9 155.2 | 132.5 116.4 | 103.2 774.6 292.7 223.6 | 177.6 | 149.1 127.3 111.8 99.1 741.6 280.3 214.1 170.1 142.7 121.9 107.

94.9

100. 96.6 93.1 89.4 85.6

90.7 87.7 84.5 81.2 77.7

83.3 80.5 77.6 74.5 71.4

76.8 74.2 71.5 68.7 65.8

71.4 69. 66.5 63.9 61.2

66.6 64.3 62. 59.5 57.1

62.5 60.4 58.2 55.9 53.5

58.8 56.7 54.7 52.5 50.3

123.7 119.5 115.2 110.7 106.

75. 72.5 69.9 67.1 64.2

500 000 450 000 400 000 350 000 300 000

707.1 267.2 204.1 162.2 136.1 116.2 102.1
670.8 253.5 193.7 153.8 129.1 110.3 96.8
632.4 239. 182.6 145. 121.7 103.9 91.3
591.6 223.6 | 170.8 135.7 113.9

85.4 547.7 207. 158.1 125.6 105.4 90. 79.1

90.5 85.8 80.9 75.7 70.1

81.7 77.5 73. 68.3 63.2

74.1 70.3 66.3

68. 64.6 60.9 56.9 52.7

62.7 59.5 56.1 52.6 48.6

58.3 55.3 52.2 48.8 45.2

54.3 51.6 48.6 45.5 42.1

51. 48.4 45.6 42.7 39.5

48. 45.5 42.9 40.1 37.1

101. 95 8 90.4 84.5 78.3

61.3 58.1 54.8 51.2 47.4

97.2

[blocks in formation]

250 000

500.

189.

144.3 114.7

96.2

82.1

72.2

64.

57.7

52.4

48.1

44.3

41.2

38.4

36.1

33.9

71.4

43.3

DIAMETERS OF WIRES IN STRANDS.—(Continued.)

[blocks in formation]
[blocks in formation]

1 000 000 950 000 900 000 850 000 800 000

61. 58. 54.9 51.9 48.8

96.1 91.3 86.5 81.7 76.9

120.8 152.4 192.9 244.1 307.8 384.5 493.8 625. 114.8 144.8 183.2 231.9 292.4 365.3 469.1593.8 108.7 137.2 173.6 219.7 277. 346.1 444.5 562.5 102.7 129.5 164. 207.5 261.6 326.8 419.8 531.3 96.6 121.9 154.3 195.3 246.2 307.6 395.1 500.

771.6 733. 694.4 655.9 617.3

976.6 1 562. 927.8 1 484. 878.9 1 406. 830.1 1 328. 781.3 1 250.

3 121. 2 965. 2 809. 2 653. 2 497.

6 299. 10 000. 5 984. 9 500. 5 669. 9 000. 5 354. 8 500. 5 039. 8 000.

92.5 87.9 83.8 76. 74.

750 000 700 000 650 000 600 000 550 000

45.8 42.7 39.7 36.6 33.6

72.1 67.3 62.5 57.7 52.9

90.6 114.3 144.7 183.1 230.8 288.4 370.4 468.8 84.6 106.7 135. 170.9 215.5 | 269.2 345.7 | 437.5 78.5

99.1 125.4 158.7 | 200.1 249.9 321. 406.3 72.5 91.4 115.7 146.5 184.7 230.7 | 296.3 375. 66.4 83.8 106.1 134.3 169.3 211.5 | 271.6 343.8

578.7 540.1 501.6 463. 424.4

732.4 1 172. 2 341. 683.6 1 094. 2 185. 634.8 11 015. 2 029. 585.9 937.4 | 1 873. 537.1 859.31 717.

4 724. 7 500. 4 409. 7 000. 4 094. 6 500. 3 779. 6 000. 3 464. 5 500.

69.4 64.8 60.1 55.5 50.9

[blocks in formation]
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