. Electric railway journal . Assuming that city construction averages$50,000 per mile, and high tension insulators cost 40 centseach, the cost of high tension insulators is a little over1/100 of 1 per cent of the total cost of construction, exclu-sive of cars, buildings and power houses on a large streetrailway system there. Such being the case, the advancefrom an admittedly inadequate factor of to one of ,the sufficiency of which is yet to be demonstrated, seemsnot over-cautious in the light of the great importance of ab-solute continuity of service in heavy street railway opera-tion
. Electric railway journal . Assuming that city construction averages$50,000 per mile, and high tension insulators cost 40 centseach, the cost of high tension insulators is a little over1/100 of 1 per cent of the total cost of construction, exclu-sive of cars, buildings and power houses on a large streetrailway system there. Such being the case, the advancefrom an admittedly inadequate factor of to one of ,the sufficiency of which is yet to be demonstrated, seemsnot over-cautious in the light of the great importance of ab-solute continuity of service in heavy street railway opera-tion demanded now. Other qualifications of the suspended insulator are: Su-perior accessibility for cleaning and observation; and supe-perior resistance to missiles. If wood construction were to be attempted on a scale cor-responding to that of the steel tower, the cost would prob-ably exceed that of the steel tower and would last onlyeight or ten years, whereas the galvanized iron tower should ,400,000 400,000200,000. 10 20 30 iU 50 Uo 70 60 110 1O0 110 120 130 140 150 Percentage Power Distribution—Fig. 1.—Cost of Re-Leading Cable Ac-cording to Cost of New Cable Less Scrap last indefinitely. Also, greater durability of the conductoris assured when it is strung on suspended insulator becauseof less crystallization at the point of support. It has beenthe experience in California where after a years operationon spans varying from 350 to 4000 feet and towers varyingfrom 50 to 300 feet high and 60,000 volt lines that no shortcircuits are made in high winds. As steel towers consist ofmany separate pieces which are only assembled when atthe point of erection, it is easier to transport a tower piece-meal to a location difficult of access than it would be totransport a wooden pole of equal height. Low Tension Feeders The committee recommends the use of paper insulatedand lead covered cable for underground service. Specifica-tions for this material have been prepared. There ar
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