Abstract: An electrical wiring system for use in construction of buildings consisting of fittings moulded of a dielectric material with internal circuitry and wire attachments that can be quickly and easily installed in round holes in panel materials of varying thicknesses by means of a metal clip. These fittings connected to each other with BX cable provide a foolproof installation that is impossible to short out and can be accomplished by labor not skilled in electrical wiring. Not only is the labor cost involved in installing this system reduced, but the material costs are also greatly reduced compared with the costs of conventional wiring.

Abstract: An additional N.sup.+ region is provided in a P type substrate adjacent to a protective N.sup.+ resistor region with an insulating layer and metal layer interposed between the N.sup.+ region and the N.sup.+ resistor region. The N.sup.+ resistor region, the oxide layer, the polysilicon layer and N.sup.+ region constitute an MOS transistor, respectively corresponding to a drain region, a gate insulating layer, a gate electrode and a source region of the MOS transistor. When a very high excessive voltage that otherwise would destroy the PN junction between the substrate and the resistor region is applied to the input terminal, the MOS transistor is rendered conductive and the excessive voltage is absorbed.