NORTHWEST BUILDING, NEWARK, N. J., UNDER CONSTRUCTION.
Nine stories high; dimensions, 90 ft. by 106 ft. Weight of steel used, 2,000,000 lbs.
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surface coated with an insulating compound; or, second, to use what is known as flexible armored cable, as shown in Fig. 16. These pipes are in stalled by fastening them in place by means of straps, illustrated in Fig. 17.
All elbows and bends in conduit must be made so that the conduit or insulating lining of In many of the large cities this method is no longer permitted.
the same will not be injured. The radius of the inner edge of any bend should not be less than inches, nor should there be more than the equivalent of four 90-degree bends in a run of conduit from outlet to outlet, neglecting the bend at the entrance to the outlet box. The wires are pulled into the conduit after it is in stalled, by means of steel tape or fish wire.
Still another method of installing wires is employed, in which they are placed entirely out of sight. In this case, the work is known as concealed work. One of the first methods of installing concealed work was to fasten the wires to the ceiling and walls before they were plas tered, the wires being entirely covered when the building was complete. This method is a very dangerous one, and is no longer permitted by the Fire Underwriters. The cleat and knob method may be employed where the floors and walls will permit, the wires being placed so that they will not touch anything except their insu lating supports, and being passed through insu lating tubes in floors, walls, and joists, as shown in Fig. 18. The wires are also encased in a cir cuit or loom such as is shown in Fig. 19, where they cross or enter outlet-boxes. This is a much safer method than the previous one; but the wires are still exposed to mechanical injury by workmen, such as plumbers and carpenters who are making repairs.
The most satisfactory method of all for in stalling the wires, is to place the conduit while the building is being constructed, in which case it is placed out of sight and affords the best of protection for the conductors. The conduit is connected to the boxes by means of a lock nut and bushing, which serve as a mechanical con nection. The bushing prevents the insulation on the wires from being injured when it is pulled into place.
The importance of using the utmost care in arranging and putting in place electric light wires in a building cannot be too strongly em phasized. The National Board of Fire Under writers have compiled a set of rules and specifi cations which govern the installation of elec trical apparatus in buildings insured in compa nies belonging to the association. In addition to this, the Electrical Inspection Departments in some of the larger cities have a set of rules and specifications governing all wiring within the limits of the city. The order of procedure in such a city is to make application to the Elec trical Department for a permit to do the wiring. Upon receipt of the permit, the wiring may be installed, and, when completed, it must be in spected by one of the City Inspectors, who de termines whether it fulfils all requirements as laid down in the book of Rules and Specifica tions. When work has been passed upon by the Inspector, the electrical company is given notice that they may connect to the building and give the desired service. If the city or town does not require such an inspection, it is nevertheless always well to follow the code of the Fire Un derwriters, as likelihood of fire is thereby reduced and insurance rates lowered.