Fig. 916.—Greenfield flexible steel armoured lead covered conductors for use in wet places, such as breweries, packing houses, cold storage buildings, coal breakers and the like, and for underground construction, in which classes of work these materials are being extensively and satisfactorily used.
Ques. What are the features of armoured cable?
Ans. It is flexible and the conductors are well protected from mechanical injury. While this form of wiring has not the advantage of the conduit system—namely, that the wires can be withdrawn and new wires inserted without disturbing the building in any way whatever—yet it has many of the advantages of the flexible steel conduit, and it has some additional advantages of its own. For example, in a building already erected, this cable can be fished between the floors and in the partition walls, where it would be impossible to install either rigid conduit or flexible steel conduit without disturbing the floors or walls to an extent that would be objectionable.
Figs. 917 to 920.—Greenfield flexible conduit tools. Special tools are necessary for installing this type of conduit. Fig. 917, universal reamer; [fig. 918], bushing tool; [fig. 919], cable armour cutter; [fig. 920], vice for holding conduit. To remove cable armours, clamp the conductor firmly in the armour cutter and with a pair of cutting pliers back the armour off, one strip at a time, to the point of contact with the cutting edge of the tool. The vise for holding conduit takes all sizes. The conduit can be cut with an ordinary hacksaw. To protect the insulation against any possible injury while the wire is being drawn in, a soft metal bushing should be inserted in the end of the tube and secured permanently thereto by means of the bushing tool. The bushing provided for this purpose has an outside thread, which permits its being screwed into the end of the tube and then expanded by the use of the tool. The tool should always be used after the bushing has been screwed into the pipe, then the bushing tool should be inserted.
Ques. How should armoured cable be installed?