ix Chapter 11 Boxes, Fittings, and Covers 161 simply hold the box against the framing mem- ber and drive the captive nails into the wood. Be careful not to drive the nail too far, which can easily warp or even break the box. with NM cable. Metal boxes are available in more sizes than nonmetallic, and most gangable boxes are metal. Metal boxes must be grounded, either through metal conduit or armored cable or via a connection to the circuit ground wire. 11.1.8 Old Work Boxes Standard metallic and nonmetallic boxes for new construction often are called “new work” boxes. This means they are designed to be installed when the building’s framing is exposed, before the drywall or other wall or ceiling finish mate- fi rial is installed. Another type of box has spe- cial features that allow it to be installed after the drywall is up. This is called an old work, remodel, or cut-in box. Old work boxes are inserted into a hole cut into the wall material and employ a variety of devices for securing the box without having to attach it to the framing. All of them have flanges on the front edges of the box to hold the box against the exposed face of the wall and keep it from slipping into the hole in the wall. On PRO TIP Settingg ti ng B Bo x Depth Boxes oxes must be installed sta so their front fr edges are are flush with the he surface of the he wall or ceil- in ing finish matter eria l. The most co commo n finish is is 1/2″ drywall, l l, so boxes typically ca are installed d so ″ they extend end 1/2″ from thee front edges of s f stu ds ″ or joists. ts. To help you set et the proper box ox depth, many ny nonmetallic box boxe s have a raiseed d edge or tabs bs to indicate box box depth. Otherw rwise, you can u use a small shim m cut from 1/2″ d drywa ll or ply- ″ wood as a gau aug e to set the box ox depth. Hold the e shim against nst the stud or jois oi st , position the bo box so its fron ont edges are flush ush with the shim, m , then fasten n t the box to the fra framin g. 11.1.7 Metallic vs. Nonmetallic Boxes it from slipping into the hole in the wall. On the body of the box, two or more rotating tabs or bendable clamps (or other mechanisms) are drawn up against the backside of the wall mate- s e 11 . 1 . 7 M eta ll ic vs . Nonmeta ll ic B o x es While metallic boxes are preferred or requiredd for many applications, nonmet become the standard tacles wall . O wo or more rotating tab dable clamps (or other mechanisms) ar drawn up against the backside of the wall mate bs e s required ns, nonmetall the standard fo tacles, a 144 Section 3 Installation PROCtEDURE Offse Bend before an Obstruction 1 . M easure thedistancebetweentheconnec e c- tion pointandheighobofthchartoructiontouseto the struction. 2. M ea sure the t e obstr tion. n. 3. C onsu ltanoffsetbelendouwoulshl calculator ca l cu l ff ff determine the ang y ud l d ik l ike for the offsetbends. Notethe the shrink amount ff ff and the distancebetweenbe en ben ds for your chosen angle. 4. A dd the shrinkamouMeasurefromthdeand ount nt to the distancestart- you measured in step ep 1. 1 . M ing endofthecon he condui t you willben make a markatthisbetweenbendmfou ark at calculateddistsance. e. 5 . Ungthedi si the distanc e found und in step 3,ma 3, mark theconduitbackfromtheegin- the first fi mark. mark. Thenewmarkrepresentst T s the the b nngofthefirstbend. ning fi 6. 6 Placethe conduitbendlacewithyourfoot. ende der handleonthe n the fl oor andsecureduitintheofbenderesnothhead. it inp it in yo ur foot fl Positiontherkond c ondu ender so that the firstma rk ( b ( beg inning firstb of fi fi rst be nd ) is fi fi alignedwith10-10. with thearrowontheben t on th e b bende r SeeFigu g ure ure 7. Bndth3,cbeingngltoethenottokinfrkomIthe en d the o the aangle ng l in s n ste step care fu l not n ex examp le,the a ng l e is 45 8. 8 . Whoutrebender,rotatenthemarkisedignedwierfhandar-e..itlconduthethoandiditls°ctiobeinedetermindel801seheduitltangalgconthet.n.tructioobsithekinkearsltocnotlnduitwithanltoonduse.°45cithcoellgthecarefuthecarelfuaratpaoonduitsuycthalmovineseckbeingonduitit.thisdetermined it e moving the , rotate he s l ide untilthe t he seco nd wi th row. Ma ow. M a ke sure ion is perfect is perf ect bend 9. B en 9 . B en d t d the ang ed step step 3, ot 10. C 10 C o nfirm duit bs fi Making an Offset Bend (After Measuring and Marking) he standard fo tacles, a ns , e s e able clamps (o drawn equired metall e e ab ab o or more ro wall . O all . O ab wo or m ore ro r dable clamps (o e drawn bs e require , non metall standard fo tacles, a Pro Tips provide you with advice and guidance that t is i s especially applicable for on the job. Step-by-Step Procedures are a re high ig hl ighted throughout the textbook to provide cle cl ea r instructions in for hands- on service activities. You ou can n refer back to these procedures easily. Thinking Green notes highlight key items related to sustainability, na i ty energy effi ciency, and environmental ffi issue u es . Summary feature provides an additi it io nal review tool for you and reinforces key learning n g objectives. Review Questions allo l ow you to demonstrate knowledge, identification, c and comprehension of fi fi chapter material.l Internet Resources provide a listing of websites that at provide content related to the electrical wiring g p pr ofession. Know the Code questions, which require u ir the use of the National Electrical Code to answer, er help you gain knowledge of and become comfo f or table with the NEC. lable in allic, and mos etal. Metal bo either throu ., I In nc nc c . Making an Offset Bend (After Measuring and Mark g er, . bllisherl e ark r 80 Section 1 Fundamentals 5.6. 1 Residential ElectricalSystem The power from the utility enters your house through the service entrance, which is where the electric meter is located. See Figure 5-30 . The electric meter records the amount of power you use each month. The electric company reads the meter every month and charges you for the amount of energy used. After passing through the electric meter, the power is fed into the home’s main elec-as trical service panel, commonly known the breaker box. This is where the power is divided into branch circuits for the different THINKINGGREEN Sol Solar Power we we Plants nts Photovoltaic vo vo l ( ( PV PV) solar so l ar panel s ar are lik l ike miniature mi ure ure powe wer wer plants nts. Ther T heir only o source u rce of of pow power i s s su sun- lig l igh ight. Largecommercithleelalecopricaaltioucedgridb,otffal rge omme a so o l a r opera tions addsolar- dd dd genera eratedpowertoto d pow h e e l ect ca l utility ty ty o ff - ff ff setti etting g th the a e am ount of po power er produc uce by y bu rn- n- in ing fo fos sil si l fuel s or using or u sing nuclearfuel.forresi nu c f f ue ue A esiden en tia l solarsystemcthesyste o l ar s c reates reate its o s own po pow power or use se in th n the hou househo ld. I f d. I f the ys tem is s co co connect cte ed tothegrid, to he excess solar-gener so l r-g eratedpo po power is addedtothey.grid s add ed to and mayb may be purchasedbytheuilityco pur ed ed he uti l ity compan Outlet and lights Outlet Switch 3-way switches Transformerer Utility power lines l r r . bl e r Go odheart-Willcox Co..,IInc nc . . Goodheart-Willcox Figure5-30. T he hefiartofahouseholdeitlectricaoflto system is the main service panel. I t receives power fromthePublisheris service entrance wiringandfor distributes to all the individualcircuitsinthehouse.Copyright AC compressor Heating/c ooling unit Washer Refrigerator Ou Range Utility meter enclosure Circuit breakers Service entrance Main serviceforThey panel Transform Dishwasher System grounddamage Dryer 154 Section 3 Installation Copyright Goodheart-Willcox Co., Inc. Summary • Raceways are complete systems enclosing and protecting wiring. include conduit or tubing, boxes, and fi ttings.of fi fi • Types rigid conduit and tubing include EMT, IMC, RMC, and rigid PVC. Flexible raceway materials include ENT, FMC, and LFMC.IMC, • RMC, and PVC conduit can be used interchangeably in many applications, but PVC cannot be used to support fi xtures. fi • Most conduit and tubing can be custom- bent on the jobsite or can be installed with prefabricated bends and other ttings for fi fi routing. • The NEC has specifi c requirements fi raceway applications and installation, including maximum mounting distances, suitable locations, and preparation procedures. Internet Resourcesprovidethis The following companies additional information related to the topics in chapter. Use a search engine to fi nd the company’s home fi page and explore the resources available on the website. Wireman. Retailer of specialty electrician tools. Website includes a regularly updated apps section that lists popular apps for conduit bending and other reference tools for electricians. Ideal Industries. Manufacturer of electrical tools and supplies. Website features an illustrated Bender Guide covering the basics of conduit bending. The “Product Videos” page has several detailed videos on conduit bending calculation and technique. Rigid. Manufacturer of pipe vises and cutting and threading tools useful for working with metal conduit. Review Questions Answer the following questions using the information provided in this chapter. 1. True or False? When wiring with rigid metal conduit, a grounding conductor is required. 2. When rigid conduit is cut, it is important that it be _____ to r _ _ emove any sharp burrs that could the _ _____ _ during wire installation. 3. Intermediate metal conduit is commonly sold in which of the following lengths? A. 3′ B. 6′ C. 8′ D. 10′ E. 12 ′ 4. A(n) _____ bend is used when the conduit has turn 90°.conduit 5. Shortening of length due to bends is known as _____. 6. Flexible metal conduit is also called _____. 7. LFMC stands for _____. 8. True or False? Electrical metallic tubing cannot be used as an equipment ground. 9. Which article of the NEC outlines rules regarding rigid metal conduit? 10. Which article of the NEC outlines rules regarding rigid PVC conduit? 11. PVC conduit bends are made by first fi _____ the conduit. 12. True or False? PVC conduit can be direct buried. 13. FMC must be mounted of a box and every _____withinthereafter.flush-flallows_____inches _ _ feet 14. A(n) _____ is a shallow bend that fl mounted conduit to reach a box knockout. 15. True or False? Surface-mount raceways are allowed in both dry and damp locations. Know the Code A copy of the NEC 2017 is required to answer these questions. 1. What is the title of Section 250.118? 2. What does the informational note in Section 320.10 state? h 9 Which arti etal conduit? answer t nformatio