used. The NEC® also requires that the outsideedges of outlet and switch boxes without flushplates NOT be recessed more than 1/4 in. belowthe surface of the finished wall.ReceptaclesRECEPTACLES are used to plug in lights andappliances around the building. Some of the typesof receptacle commonly used in interior wiring arediscussed in the following paragraphs in the orderof their frequency of use.A CONVENIENCE OUTLET (fig. 9-18) is aduplex receptacle with two vertical or T-slots anda round contact for the ground. This ground isconnected to the frame of the receptacle and isgrounded to the box by way of screws that securethe receptacle to the box.A RANGE RECEPTACLE (fig. 9-19) maybeeither a surface type or a flush type. It has twoslanted contacts and one vertical contact and israted at 50 A. Receptacles for clothes dryers aresimilar but are rated at 30 A. Range and dryerreceptacles are rated at 250 V and are used withthree-wire, 115/230 V, two hot wires and aneutral. A receptacle for use with an air-conditioner taking 230 V is made with twohorizontal slots and one round contact for theground.Also used in the Navy are strips that allowmovement of the receptacle to any desiredlocation. These strips are available in 3-ft and 6-ftlengths and may even be used around the entireroom. This type of outlet is particularly desirablein rooms where portable equipment or fixtures,Figure 9-18.-A typical duplex convenience outlet.Figure 9-19.-Range receptacle.such as drafting tables and audio-visualequipments, are used. Specialty outlets (weather-proof are used in all exterior locations becausethey resist weather damage.SwitchesFor interior wiring, single-pole, three- or four-way toggle switches are used. Most of theswitches will be single-pole, but occasionally athree-way system is installed, and on rareoccasions, a four-way system.A single-pole switch (fig. 9-20) is a one-blade,on-and-off switch that may be installed singly orin multiples of two or more in the same metal box.In a three-way switch circuit (fig. 9-21), thereare two positions, either of which may be usedto turn a light ON or OFF. The typical situationis one in which one switch is at the head of astairway and the other at the foot.A four-way switch (fig. 9-22) is an extensionof a three-way circuit by the addition of a four-way switch series.Figure 9-20.-Single-pole switch circuit.9-14
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