Hawkins electrical guide. Questions, answers & illustrations; a progressive course of study for engineers, electricians, students and those desiring to acquire a working knowledge of electricity and its applications; a practical treatise (1914)
Hawkins, N. (Nehemiah), 1833- · New York, T. Audel · leaf 145
installations which will be discontinuedbefore the wood decays. UNDERGROUND WIRING 833 Wooden Built-in Conduits.—Within recent years severalforms of wooden built-in conduit have been designed and suc-cessfully used for permanent work. They possess several ad-vantages over any of the duct systems,… … Fig. 980.—Perspective view of wooden built-in conduit. It consists of an outer rectangularcasing of wood which is lined inside with impregnated felt. Oues. How are wooden built-in conduits installed? Ans. A wooden trough is laid in a trench about 18 inchesdeep. Porcelain carriers as shown in figs.…
Electrical engineering
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