Electrical engineer; an illustrated record and review of electrical progress Volume 5 - Softcover

This historic book may have numerous typos and missing text. Purchasers can download a free scanned copy of the original book (without typos) from the publisher. Not indexed. Not illustrated. 1890 edition. Excerpt: ...to break the insulation and thus increase the danger of accident, and the possibility of the conductor being reached by occupants of offices or flats is greatly diminished. The objection to an iron staple over a heavy wire or cable is that sooner or later the weight of the conductor will sag, weakening the insulation, if not cutting it through completely. The wooden cleat is scarcely better. Experience has shown that upon a line where such cleats are used, the retention of moisture by the wood is almost certain to weaken that point, so that when a ground is developed elsewhere, adding to the strain already existing, the cleat aids materially in the development of the second ground, with its consequent unpleasantness. It costs a little more at the time, but in all such positions the farther we get from the wall or the wood, with air for both ventilation and insulation, the greater the economy in the long run. No inconsiderable expense is sometimes incurred in covering arc light conductors within a building with a neat and ornamental moulding. It is pretty but expensive, when, as in an instance where I was a witness after the fact, an unnoticed leak from an imperfect skylight developed a second ground on a heavy circuit, and the insurance fell short of the damage done. In another instance, where wooden cleats were used to confine a cable in a sidewalk area, grounds were developed in half-a-dozen places almost simultaneously from a very similar cause, and an expensive piece of conductor was ruined. In the first of these two instances painting or even bronzing the wire with varnish bronze would have been sufficiently ornamental, and the porcelain knobs could have been treated similarly. In any event but a few days after a line wire is run through a...