A unit employed in the late 19^{th} – early 20^{th} centuries to describe galvanized telephone and telegraph wire. Consult the sources for its meaning.
1
Galvanized wire varies between wide limits in its electrical and physical properities. There are three grades used in electrical work known in the trade as Extra Best Best, Best Best, and Steel, abbreviated to E. B. B., B. B., and Steel. The electrical properties of these wires are expressed by the product of the weight per mile and the resistance per mile. This product is a constant quantity at a given temperature for any size of wire, provided the electrical properties of the materials are the same.
4 B.W.G. | 14 B.W.G | |
Pounds per mile | 787 | 96 |
Ohms per mile | 5,972 | 48,958 |
Product | 4700 | 4700 |
This product may be called the mile ohm or the mile pound. The mile ohm is the weight in pounds of a wire one mile long, having a resistance of one ohm. The mile pound is the resistance in ohms of a mile of wire weighing one pound.
Wire in Electrical Construction.
Trenton, NJ: John
A. Roebling's Sons Company, 1916.
Page 123.
2
Mile Ohm. — In telephone and telegraph practice, the weight of a piece of wire one mile long having a resistance of one ohm. The poorer the conductor the greater the weight of the mile ohm, hence the weight per mile-ohm is a convenient way of expressing the electric conductivity of wires.
To ascertain the mileage resistance of any wire, divide the weight per mile ohm, by the weight of the wire per mile. The weights per mile ohm of different grades of line wire are as follows: B. B. wire, about 5700 lbs.; E. B. B. wire, about 5000 lbs.; steel wire, about 6500 lbs.
The approximate weights per mile of various sizes of galvanized telegraph wire are as follows:
No. (Trenton gauge) | Lbs. per mile |
---|---|
4 | 720 |
5 | 610 |
6 | 525 |
7 | 450 |
8 | 375 |
9 | 310 |
10 | 250 |
11 | 200 |
12 | 160 |
13 | 125 |
N. [Nehmiah] Hawkins.
Hawkins' Electrical Dictionary.
New York: Theodore Audel and Company, 1915.
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Last revised: 2 January 2012.