Cyclopedia of heating, plumbing and sanitation; a complete reference work . Pig. lj. Knob and Tubu Wiring. and tubes, the circuit work being run concealed between the floor beamsand studs of ;i frame building. The knobs are used when the circuitsrun parallel to the floor beams; and the porcelain tubes are used whenthe circuits are run at right angles to the floor beams. Fig. 1 .> shows an example of knob and tube wiring. In concealedknob and tube wiring, the wires must be separated at least ten inchesfrom one another, and at least one inch from the surface wired over,that is, from the beams
Cyclopedia of heating, plumbing and sanitation; a complete reference work . Pig. lj. Knob and Tubu Wiring. and tubes, the circuit work being run concealed between the floor beamsand studs of ;i frame building. The knobs are used when the circuitsrun parallel to the floor beams; and the porcelain tubes are used whenthe circuits are run at right angles to the floor beams. Fig. 1 .> shows an example of knob and tube wiring. In concealedknob and tube wiring, the wires must be separated at least ten inchesfrom one another, and at least one inch from the surface wired over,that is, from the beams, flooring, etc., to which the insulator is fas-tened. Fig. 16 shows agood type of porcelainknob for this class ofwiring. For knob andtube wiring, it will benoted that, owing to thefact that the wiring isconcealed, the conductorsmust be kept further apart than in the case of exposed or open wiringon insulators, where, except in damp places, the wires may be run oncleats or on insula tors only one-half inch from the surface wired Porcelain Knob. 304 ELECTRIC WIRING 15 • Fibrous Tubing. Fibrous tubing is frequently used with knoband tube wiring, and the regulations governing its use are given inRule 24, Section S, of the National Electric Code. This tubing, asstated in this Rule,may be used where it is impossible and impracticableto employ knobs and tubes, provided the difference in potentialbetween the wires is not over 300 volts, and if the wires are not subs
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