Cyclopedia of applied electricity : a general reference work on direct-current generators and motors, storage batteries, electrochemistry, welding, electric wiring, meters, electric lighting, electric railways, power stations, switchboards, power transmission, alternating-current machinery, telegraphy, etc. (1916)
American Technical Society · Chicago : American Technical Society · leaf 106
jBoor should be at least 18 inches below the lowest ductson account of convenience to the workmen and to serve as collect-ing basins for water which gets into the system. The ducts shouldalways be laid with a gentle slope toward such manholes. r Common construction consists of a brick wall laid… … Fig. 48. Cement-Lined, Iron-Pipe Duct System in Course of Construction quite a waste of cable in large manholes. Care should be taken thatworkmen do not use the cables, so supported, as ladders in enteringand leaving the manhole, as the lead sheathing may readily beinjured when the cables are so…
Electrical engineering
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