Gripping wire knob

Insulator for Surface Wiring.

Although the tendency in this country within the past few years has been away from the cheaper classes of wiring toward the more expensive conduit installations, there has been a marked movement on foot in England and on the Continent for cheaper wiring schemes which would not necessarily embody the element of danger. It is necessary, of course, with the latter systems to use exposed wiring and to have fittings which will enable the work to be performed rapidly, so that the item of labor will not be a serious factor. The accompanying illustration shows a single grip insulator of white porcelain which is said to be used extensively in connection with these cheaper systems of wiring. The insulator is made up in two parts, the inner sleeve being free to move within the cylindrical shell. In using the device the cable is passed into the slots in the two parts, and these are clamped together by an ordinary wood screw, which also serves to attach the insulator securely to the wall.

Section Through Grip Insulator.

The design is quite simple, and the cable is held rigidly with¬ out any danger of its insulation being damaged—the bearing surface being large and without sharp edges. As shown in the illustration, the wood screw is separated from the cable by a porcelain partition, so that even if bare wires were stretched from the insulator there would be no danger of leakage to the screw or over the surface of the porcelain, which is glazed throughout. The device has found a wide application for warehouse and factory lighting, as well as for temporary out¬ door installations.