The Golden State: Where & How to Live, Secure, Visit, Enjoy and Thrive in California

Practical Electricity And House Wiring

Installing Non-metallic Sheathed Cable.—Splices are not permitted in cable; each piece must be continuous from box to box. Generally speaking, this cable is installed following the contour of the building, but it may run through bored holes in joists and similar timbers without further support. It may not run across open spaces without support, unless it is No. 6-2 or 8-3 or heavier. If it cannot follow the contour of the building, it may run across the bottom of joists provided a running board (a piece of 1X2 lumber serves nicely) is installed. Of course it may run along the side of any timber at any time. Fig. 127 shows the usual methods of installation.

Cable is supported by straps of the general type of Fig. 128, which must be used at intervals of not less than 41/2 ft. In any event the cable must be supported within 12 in. of every outlet box.

In permanently exposed work, it must be protected against mechanical injury in locations where such injury may happen. This protection may take the form of guard rails, boxing, by running through pipe, and so on. In any event, in passing through a floor, the cable must be protected by a piece of pipe extending at least 6 in. above the floor.

In installing this cable, the Code requires that the bends be gradual, so that if the cable were bent into the form of a complete circle, the circle would be at least ten times the diameter of the cable. Sharp bends tend to break open the fabric of the cover, exposing the individual wires.

Cable Connectors.—Cable may not be used without outlet boxes (except in the case of special surface-wiring devices shown in Chapter 22, which are really combinations of switch and outlet box, receptacle and outlet box, and so on). The cable must be securely anchored to the outlet box, this being done by using connectors of the general type of Fig. 129. Remove the fabric cover from the wires for a distance of about 6 to 8 inches, clamp the connector to the cable, remove locknut from connector, insert connector into knockout of box, and install locknut inside box. Be sure the teeth of the locknut face the wall of the box, then drive locknut home tight, to make a secure and permanent fastening; the teeth of the locknut should dig into the metal of the box.