Figure 9-21.-Three-way switch circuit.Figure 9-22.-Four-way switch circuit.Note that three- and four-way switches can beused as single-pole switches, and four-wayswitches can be used as three-way switches. Someactivities may install all small-wattage, four-wayswitches for all lighting circuits to reduce theirinventories. However, three- and four-wayswitches are usually larger than single-poleswitches and take up more box room. The sizeof a switch depends on its ampacity (relatedmaximum amperage). The ampacity and maxi-mum allowable voltage are stamped on the switch.ELECTRICAL PLANThe electrical information and layouts inconstruction drawings, just as the mechanicalplan, are generally superimposed on thebuilding plan and the plot plan.In this chapter, we will address electrical plansas those drawings that pertain to the ELECTRI-CAL (POWER) DISTRIBUTION SYSTEM,which indicate outside power lines and appurte-nances for multibuilding installations, and theINTERIOR ELECTRICAL WIRING SYSTEM.As an EA3, the electrical layout for both lightand power is your main concern. You will berequired to draw electrical drawings and layoutsfrom notes, sketches, and specifications providedby the designing engineer. Although you are notrequired to design the electrical wiring system, youmust be familiar with the methods, the symbols,and the nomenclature, as well as the basicfunctions of the components associated withthe electrical systems, its transmission anddistribution, and the circuits hookup. In addition,you must also be familiar with the codes (bothNEC® and local) and standards and specifica-tions, and be able to apply that knowledge indrawing electrical plans.STANDARDS AND SPECIFICATIONSREQUIREMENTSBecause the safety of the electrical system isof prime importance, it is imperative that all Navyelectrical installations ashore conform to rigidstandards and specifications. When preparingconstruction drawings, the EAs, like the CES, arerequired to follow the specifications issued by theNaval Facilities Engineering Command (NAV-FACENGCOM). In particular, an EA workingon electrical wiring and layout diagrams forelectrical plans should refer to the latest editionof ANSI Y32.9 and ANSI Y14.15.CodesCode requirements and installation proceduresoffer protection for the consumer against un-skilled electrical labor. Among other functions,the NEC® serves as a basis for limiting the typeand wiring to be used, the circuit size, the outletspacings, the conduit requirements, and the like.In addition, local codes are also used whenseparate electrical sections are applicable to thelocale in which the building will be built. Becertain that you always have a copy of the latestedition of the NEC® available for your use.Similarly, all of the types of electricaldevices and fixtures included in the materials listprepared for electrical plans are to meet certainspecifications and minimum requirements. Anindependent organization called Underwriters9-15
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