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Solution Manual For Illustrated Guide to the National Electrical Code, 7th Edition

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    ’ s Guide to Accompa n y the Illustrated Guide to the N E C ® , 7 e Charles R. Miller TEXTBOOK GUIDE

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    iii CONTENTS T o the . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . v SECTION 1 FOUNDATIONAL PROVISIONS UNIT 1 INT R ODUCTION T O THE N A TIONAL ELECTRICAL COD E ® . . . . . . . . . . . . . . . . . . . . . . . . . . 1 UNIT 2 DEFINITIONS Competency T est An s w ers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 UNIT 3 B O XES AND ENCLOSURES Competency T est An s w ers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2 UNIT 4 CABLES Competency T est An s w ers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3 UNIT 5 R A CE W A YS AND CONDUC T ORS Competency T est An s w ers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4 SECTION 2 ONE - FAMILY DWELLINGS UNIT 6 GENERAL P R O VISIONS Competency T est An s w ers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5 UNIT 7 SPECIFIC P R O VISIONS Competency T est An s w ers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6 UNIT 8 L O AD CALCUL A TIONS Competency T est An s w ers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7 UNIT 9 SE R VICES AND ELECTRICAL E Q UIPMENT Competency T est An s w ers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11 SECTION 3 MULTIFAMILY DWELLINGS UNIT 10 COM PREHENSIVE P R O VISIONS Competency T est An s w ers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12 UNIT 11 L O AD CALCUL A TIONS Competency T est An s w ers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14

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    iv SECTION 4 COMMERCIAL LOCATIONS UNIT 12 GENERAL P R O VISIONS Competency T est An s w ers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19 UNIT 13 NON D WELLING L O AD CALCUL A TIONS Competency T est An s w ers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2 1 UNIT 14 SE R VICE S , FEEDER S , AND E Q UIPMENT Competency T est An s w ers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2 5 SECTION 5 SPECIAL OCCUPANCIES, AREAS, AND EQUIPMENT UNIT 15 HAZARDOUS (CLASSIFIED) LOC A TIONS Competency T est An s w ers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2 7 UNIT 16 HEA L TH CARE Competency T est An s w ers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2 8 UNIT 17 INDUSTRIAL LOC A TIONS Competency T est An s w ers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2 9 UNIT 18 SPECIAL OCCU P ANCIES Competency T est An s w ers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 30 UNIT 19 SPECIFIC E Q UIPMENT Competency T est An s w ers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31 FINAL EXAM 1 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3 2 FINAL EXAM 1 ANSWERS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3 4 FINAL EXAM 2 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3 6 FINAL EXAM 2 ANSWERS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3 8

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    v TO THE Illust r ated Guide to the NEC ® 7 e is an e xciting n e w tool f or those who teach the National Elect r ical Code. This t e xt represents a d r amatic b lend of n e w presentation styles with t r ied - and - t r ue inst r uctional p r actice s . Symbolizi ng a r e v olutiona r y breakthrough in teaching mate r ial, the t e xt com m unicates with the reader p r ima r ily through visualization. If a picture is t r uly w o r th a thousand w ord s , this book is a vi r tual encyclopedia on the National Elect r ical Cod e . While technicall y accu r ate and highly detailed illust r ations tell a sto r y all their o wn, th e y are fu r the r enhance d throug h clea r l y w r itten , concis e b lo c k s o f t e x t tha t ca n b e rea d v e r y qui c kl y an d understoo d with eas e . Not only is the presentation method e xceptional, b ut also the organization of mate r ial is uniqu e . After c o v e r ing fundamental pr o visions in Section 1, Illust r ated Guide to the NEC proceeds to address code requirements according to the type of occupanc y . Comprehensi v e in f o r mation is gi v en f or one - f amily d w ell ing s , m ulti f amily d w elling s , commercial location s , and special occupancie s . In f o r mation f ound scattered throughout the Code book has been logically gathered and concent r ated under the approp r iate occupanc y . All rel e v ant aspects are thoroughly discussed and illust r ated accordingl y . As a teaching tool, this t e xt stands alon e , unli k e a n y pr e viously of f ered. Rest assured, h o w e v e r , that pr o v en t r aining methods h a v e not been sac r ificed f or the sa k e of being dif f erent. Unit objecti v es still introduce n e w ideas to the reade r , summa r ies r e vi e w the mate r ial after presentation, and competency tests rein f orce what has been lea r ned. As a v alua b le resource to the inst r ucto r , this ’ s Guide pr o vides unit competency test question an s w ers and e xplanation s , and t w o fifty - question comprehensi v e final e xam s , which can be gi v en independently or as a single test. Unequaled as a teaching tool, Illust r ated Guide to the NEC st r i v es to ma k e the entire process easier and more enj o y a b l e . F rom beginners to master elect r ician s , this t e xt has something f or e v e r y one p r acticing a t r ade in the elect r ical indust r y . The v a r iety of teaching styles f acilitated b y Illust r ated Guide to the National Elect r ical Code is essentially limitles s . Whether the inst r uctor f ocuses on a specific are a of application or w ants to teach the Code from c o v er to c o v e r , Illust r ated Guide to the NEC of f ers a visually pleasing f o r mat that holds student interest and a w a k ens comprehension. Intended not as a replacement, b ut as an indispensa b le supplement to the National Elect r ical Cod e , the t e xt t r anslates the sometimes v agu e , often r am b ling, language of the Code into cleare r , cleane r , simpler te r m s . Once the inst r uctor has com m unicated these concepts so that the student understands h o w the Code t r anslates in a p a r ticular area, the same techniques can be applied throughout this course of stud y . As the title implie s , frequent re f erences are made to the National Elect r ical Cod e . H a v e each student k eep a co p y of the current edition close at hand. On countless occasi on s , the Code pr o vides the definiti v e source of in f o r mation. Should, f or e xampl e , a n y confusion about te r minology e xist that is not cleared up b y the Definitions section (Unit 2), consulting the Code ’ s A r ticle 100 — Definitions section m a y w ell of f er the n eeded cla r ification. When e v er direct re f erences are made to the Cod e , the class will benefit b y taking the time to read the suggested a r ticle or section. The t r ue success of a n y teaching ende a v or rests in the hands of the inst r ucto r . No matter h o w good th e mate r ial, it is ultimately the inst r uctor who en r iches the mind of each and e v e r y student. It is the intention of the author and Delma r , Cengage Lea r ning to lighten this imposing responsibility b y placing e xceptional resources at the inst r uctor ’ s disposa l.

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    1 Section 1 FOUND A TIONAL PROVISIONS UNIT 1 There is no competency test for Unit 1. UNIT 2 COMPETENCY TEST 1. Answer: general purpose Reference: Article 100 ( Branch - Circuit, General Purpose ) 2. Answer: remote - control circuit Reference: Article 100 ( Remote - Control Circuit ) 3. Answer: multiwire Reference: Article 100 ( Branch - Circuit, Multiwire ) 4. Answer: periodic duty Reference: Article 100 ( Duty: Periodic Duty ) 5. Answer: main bonding jumper Reference: Article 100 ( Bonding Jumper, M ain ) 6. Answer: grounding electrode Reference: Article 100 ( Grounding Electrode Conductor ) 7. Answer: weatherproof Reference: Article 100 ( Weatherproof: Informational Note ) 8. Answer: effective ground - fault current path Reference: Article 100 ( Effective Ground - Fault Current Path ) 9. Answer: bypass isolation switch Reference: Articl e 10 0 ( Switch , Bypas s Isolation ) 10. Answer: multioutlet assembly Reference: Article 100 ( Multioutlet Assembly ) 11. Answer: wet Reference: Article 100 ( Locat ion, Wet ) 12. Answer: thermal protector Reference: Article 100 ( Thermal Protector: Informational Note ) 13. Answer: cabinet Reference: Article 100 ( Cabinet ) 14. Answer: hoistway Reference: Article 100 ( Hoistway ) 15. Answer: c) either I or II Refe rence: 210.4(C) Exceptions No.1 and 2 16. Answer: fuse Reference: Article 100 Part B. Over 10 00 Volts, Nominal ( Fuse ) 17. Answer: Festoon lighting Reference: Article 100 ( Festoon Lighting ) 18. Answer: One item named must be a basin (lavatory or si nk); the other item can be a toilet, a urinal, a tub, a shower, a bidet, or similar plumbing fixtures. Reference: Article 100 ( Bathroom ) 19. Answer: c) maximum Reference: Article 100 ( Continuous Load ) 20. Answer: resistor Reference: Article 100 ( Gro unded, Solidly ) 21. Answer: outlet Reference: Article 100 ( Outlet ) 22. Answer: branch - circuit Reference: Article 100 ( Branch - Circuit ) 23. Answer: Raintight Reference: Article 100 (Raintight ) 24. Answer: d) an indefinitely long time Reference: A rticle 100 ( Duty, Continuous ) 25. Answer: its temperature rating Reference: Article 100 ( Ampacity ) 26. Answer: 50 Reference: Article 100 ( In Sight From [ Within Sight From, Within Sight ]) 27. Answer: multifamily dwelling Reference: Article 100 ( Dwe lling, Multifamily ) 28. Answer: the earth Reference: Article 100 ( Ground ) 29. Answer: vectorial sum Reference: Article 100 ( Neutral Point: Informational Note ) 30. Answer: Yes Reference: Article 100 ( Accessible, Readily [Readily Accessible] )

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    2 UNIT 3 COMPETENCY TEST 1. Answer: d) 72; 6 (ft) x 12 (in.) = 72 in. Reference: 314.28(B) 2. Answer: 2 Reference: 382 . 15(A) 3. Answer: “X” = 24 in., and “Y” = 12 in. The “X” dimension contains both straight and angle pulls. Use the larger of t he two. “X” (straight pull) = 3 x 8 = 24. “X” (angle pull) 3 x 6 + 2 = 20. The “Y” dimension has an angle pull only. “Y” = 2 x 6 + 0 = 12. Reference: 314.28(A) 4. Answer: ½ Reference: 314.24(A) 5. Answer: 8. The total 12 AWG conductors permitted by Table 314.16(A) is 18. The flat plaster ring does not provide any additional cubic in. capacity. Two receptacles count as 4 [314.16(B)(4)], two internal cable clamps count as 1 [314.16(B)(2)], four 12 AWG THHN copper conductors count as 4 [314.16(B)(1)] , and two grounding conductors count as 1 [314.16(B)(5)] 12 AWG conductors. There are 10 existing 12 AWG conductors. Three wirenuts, two pigtails, and one equip - ment bonding jumper do not count. Reference: 314.16 6. Answer: ¼ Reference: 312.2 7. A nswer: 0.0625 in. Reference: 314.40(B) 8. Answer: bushings Reference: 314.42 9. Answer: a) none Reference: 314.23(F) 10. Answer: separate box Reference: 314.28(D) 11. Answer: 4 (6 – 2 = 4) Reference: 314.16(B)(4) and Table 314.16(A) 12. An swer: equipment grounding conductor Reference: 314.40(D) 13. Answer: ¼ Reference: 314.20 14. Answer: temperature - rated Reference: 314.17(C) 15. Answer: 0 Reference: 312.2 Exception 16. Answer: 6 Reference: Table 314.16(A) 17. Answer: 8 Refer ence: 382.30(A) 18. Answer: 4 Reference: 314.28(A)(2) Exception and Table 312.6(A) 19. Answer: individual holes Reference: 314.17(C) 20. Answer: 6 Reference: 314.27(A)(1) Exception 21. Answer: 48 times Reference: 314.71(A) 22. Answer: 1/8 in ., 1/4 in. Reference: 314.15 23. Answer: substantially equivalent Reference: 110.12(A)

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    3 UNIT 4 COMPETENCY TEST 1. Answer: 12 Reference: 334.30 2. Answer: 39.37 Reference: 324.41 3. Answer: 4 ½ Reference: 320.30(B) and (C) 4. Answer: 35 Reference: Table 326.24 5. Answer: Type MC (Metal - clad cable) Reference: 330.2 6. Answer: moisture Reference: 332.40(B) 7. Answer: c) 8 (two 6 AWG or three 8 AWG conductors) Reference: 334.15(C) 8. Answer: Type MV (Medium volt age cable) Reference: 328.2 9. Answer: d) I, II, and III Reference: 340.116 10. Answer: transition assembly Reference: 324.40(D) 11. Answer: c) 24. The question requires the answer in in., not ft (2 ft = 24 in.). Reference: 320.30(D)(2) 12. An swer: grounded circuit conductor Reference: 404.2(C) 13. Answer: seven Reference: 330.24(B) 14. Answer: 1¼ Reference: 300.4(A)(1) 15. Answer: 7 ft Section 334.23 states that non - metallic - sheathed cable installed in attics must comply with 320.23. Reference: 320.23(A) 16. Answer: c) I and III only Reference: 324.120(A) 17. Answer: Type MI (Mineral - insulated or Mineral - insulated, metal - sheathed cable) Reference: 332.2 18 . Ans wer : c ) 90°C Reference: 320.80(A) 19. Answer: d) 72. The quest ion is looking for in. 6 (ft) x 12 (in.) = 72 (in.). Reference: 330.30(B) and (C) 20. Answer: 168 Reference: Table 326.80 21. Answer: b) 12 Reference: Table 300.5 22. Answer: soldered Reference: 394.56 23. Answer: 1 / 16 Reference: 300.4(A)(1) 24. Answer: 20, 30 Reference: 324.10(B)(2) 25. Answer: 6 Reference: 332.30 26. Answer: 18 Reference: Table 300.5

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    4 UNIT 5 COMPETENCY TEST 1. Answer: d) listed or approved for use in wet locations and arranged to drain. Reference: 225.22 and 230 .53 2. Answer: quarter, ¼, or 90° Reference: The answer can be found in most of the raceway articles, such as 344.26 for rigid metal conduit. 3. Answer: 3.356 Reference: Chapter 9, Table 4. The cross - sec - tional area is the total area (100%). 4. Answer: ¾ Reference: 344.28 and 346.28 5. Answer: c) I and II only Reference: 380.12(5) and 380.76 6. Answer: 75% Reference: 376.56(A) and 378.56 7. Answer: header Reference: 374.2 8. Answer: 1¼ Reference: 300.4(A)(1) 9. Answer: 4 Re ference: Table 348.22 10. Answer: 16 Reference: 342.30(B)(2) and Table 344.30(B)(2) 11. Answer: 20% Reference: 376.22(A) and 378.22 12. Answer: induction Reference: 300.20(A) 13. Answer: multioutlet assembly Reference: Article 100 ( Multioutlet Assembly ) 14. Answer: galvanic action Reference: 342.14 and 344.14 15. Answer: 10 Reference: Informative Annex C, Table C9 16. Answer: six (6) Reference: 314.28(A)(2) 17. Answer: ¼ Reference: 300.6(D) 18. Answer: 6 Reference: 250.102(E)(2) 19. Answer: c) I and III only Reference: 372.18(B) 20. Answer: 3 Reference: 362.30(A) 21. Answer: wet Reference: Article 100 ( Location, Wet ) 22. Answer: b) shall be removed from the race - way. Reference: 390.8 23. Answer: corrosion protection Reference: 344.10(B)(1) 24. Answer: 8 AWG Reference: 310.106(C) 25. Answer: 180 Reference: Table 300.19(A) 26. Answer: 4 AWG Reference: 300.4(G) 27. Answer: 3 ft Reference: 378.30(A) 28. Answer: 10, 3 Reference: 342.30(B)(4) 29. Answer: 1.496 sq in. The cross - sectional area is the total area (10 0 %), regardless of conductors. Reference: Chapter 9, Table 4 30. Answer: equipment bonding jumpers Reference: 250.98 31. Answer: 3 Reference: 344.30 32. Answer: 7 Reference: Table 352.30 33. Answer: 0.8 Reference: Chapter 9, Note 7 34. Answer: 30° (30 degrees) Reference: 376.23(A) and 378.23(A) 35. Answer: 60 Reference: 310.15(B)(2)(c) 36. Answer: unobstructed Reference: 376.56(B)(5)

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    5 Section 2 ONE - F AMI L Y DWELLINGS UNIT 6 COMPETENCY TEST 1. Answer: b) 20 ampere Reference: Table 210.21(B)(3) 2. Answer: b) multiwire branch - circuits Reference: 300.13(B) 3. Answer: 5 ½ Reference: 210.52 and 210.52(4) 4. Answer: 6 Reference: 300.14 5. Answer: b) must be the same size as the insulated circuit conductors Reference: Table 250.122 6. Answer: 15 Reference: 406.3(B) 7. Answer: 16 Reference: 410.30(A) 8. Answer: b) 25 amperes Reference: 210.18 9. Answer: receptacle outlet Refer ence: 210.50(A) 10. Answer: b) I and III only Reference: 406.4(A) 11. Answer: 70 Reference: 314.27(C) 12. Answer: 18 Reference: 210.52(A)(3) 13. Answer: current, voltage, temperature Reference: 410.52 14. Answer: 5 0 Reference: 314.27(A)(2) 15. Answer: 15 or 20 Reference: Table 210.21(B)(3) 16. Answer: individual Reference: Article 100 ( Branch - Circuit, Individual ) 17. Answer: 12 Reference: 210.52(A)(1) 18. Answer: c) II and III only Reference: 406.4(D)(2)(c) 19. Answer: receptac le outlet Reference: Article 100 ( Receptacle Outlet ) 20. Answer: d) 0.0 in. Reference: 314.20 21. Answer: d) hallway Reference: 210.70(A)(1) and (2) 22. Answer: 40 or 50 Reference: Table 210.21(B)(3) 23. Answer: grounded conductor Reference: A rticle 100 ( Grounded Conductor ) 24. Answer: c) the circuit conductors between the final overcurrent device protecting the circuit and the outlet(s) Reference: Article 100 ( Branch - Circuit ) 25. Answer: d) II or III only Reference: 240.15 (B) and (B)(1)

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    6 UNIT 7 COMPETENCY TEST 1. Answer: 4. The maximum distance to a receptacle is 2 ft Reference: 210.52(C)(1) 2. Answer: 8 Reference: 410.10(D) 3. Answer: c) 15 or 20 amperes Reference: Table 210.21(B)(3) 4. Answer: b) 10 AWG Reference: 210.1 9(A)(3) Exception No. 2 5. Answer: 194 Reference: 410.11 and 410.115(A) 6. Answer: 2. A vehicle door in a garage is not considered an outdoor entrance or exit. Reference: 210.70(A)(2) 7. Answer: clothes closets Reference: 240.24(D) 8. Answer : b) 100% Reference: 210.21(B)(1) 9. Answer: 6 Reference: 210.50(C) 10. Answer: 20 Reference: 210.19(A)(3) Exception No. 1 11. Answer: 9200; 4 + 5.5 + 5.5 = 15 kW. Increase Column A by 15% (15 – 12 = 3 x 5% = 15%) 8 x 15% = 1.2 kW 8 + 1.2 = 9.2 k W 9.2 x 1000 = 9200 watts. (An answer of 9.2 is incorrect because the answer should be given in watts, not kW.) Reference: Table 220.55, Note 4 12. Answer: 80 Reference: 210.23(A)(1) 13. Answer: 6 Reference: 410.16(C)(3) 14. Answer: 50 Reference: Article 100 ( In Sight From ) 15. Answer: one Reference: 210.52(H) 16. Answer: c) I or II only Reference: 422.31(B) 17. Answer: six Reference: 210.70(A)(2)(3 ) 18. Answer: readily accessible Reference: 240.10 19. Answer: 6.5 . The cord must be b etween 3 and 6.5 ft for built - in dishwasher cords. Reference: 422.16(B)(2)(3 ) 20. Answer: b) I and II only. A receptacle in a detached garage is required only if the garage has electrical power. Reference: 210.52(G) 21. Answer: d) I, II, or III Reference: 210.52(B)(1) and 210.52(B)(1) Exception No. 2 22. Answer: c) II or III Reference: The laundry circuit must be a 20 - ampere circuit [210.11(C)(2)]. A single receptacle cannot exceed the rating of the circuit [Article 100]. A duplex recept acle rated 15 amperes is per - mitted on a 20 - ampere circuit [Table 210.21(B)(3)]. 23. Answer: 3 Reference: 210.52(D) 24. Answer: 6 Reference: 210.52(C)(5) Exception 25. Answer: b) I or II only Reference: 210.11(C)(3) and 210.11(C)(3) Exception 26 . Answer: 20 Reference: 210.11(C)(4) 27. Answer: 22, 30 Reference: 110.26(A)(4)

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    7 19. Answer: 2 AWG coppe r . Multipl y th e service ratin g b y 8 3 percen t [310.15(B)(7)(1)] 12 5 × 83 % = 103.7 5 = 10 4 amperes. I n accordanc e wit h th e 75° C column o f Tabl e 310.15(B)(16) , th e ampacity o f a 2 AW G coppe r conducto r i s 115 20. Answer: amperes. 8 AWG copper 21. Answer: 4 AWG copper UNIT 8 COMPETENCY TEST 1. Answer: 75, four Reference: 220.53 2. Answer: 7092 volt - amperes. First, find the total floor area of the house. Multiply the dimensions of each floor and add the two: 30 x 48 = 1440 sq ft (first floor); 22 x 42 = 924 sq ft (second floor) ; 144 0 + 92 4 = 236 4 tota l s q ft. Next, multiply the total square ft by three (3) volt - amperes per square foot: 2364 x 3 = 7092 volt - amperes. This house has a lighting demand load of 7092 volt - amperes. Reference: 220.12 3. Answer: None Reference: 220.14(J) 4. Answer: 1500 Reference: 220.52(A) 5. Answer: d) 6.6 kW. The question is asking for the service demand load, not the branch - circuit demand load. 3. 5 + 3. 5 + 5 = 1 2 k W (fo r thre e units). Table 220.19, Column B for three units has a demand factor of 55%. 12 x 55% = 6.6 kW. Reference: 220.55 and Table 220.55 6. Answer: 14.58. 5 kVA (5000 VA) is the minimum dryer load. 5 000 ÷ 240 = 20.83 (amperes) 20.83 x 70% = 14.58 (neutral amperes). Reference: 220.54 and 220.61(B) 7. Answer: 2495 volt - amperes; dishwasher 1 x 1000 = 1000 (single - phase motor current ratings are located in Table 430.148); disposer 5.8 x 115 = 667; com pactor 7.2 x 115 = 828; 1000 + 667 + 828 = 2495 volt - amperes. Note: No demand factors are allowed on three or fewer fastened - in - place appliances. Reference: 220.53 8. Answer: 100 Reference: 230.79(C) 9. Answer: 6 AWG. Multiply the service rating by 83 percent [310.15(B)(7)(1)] 175 x 83 % = 14 5 amperes . I n accordance wit h th e 75° C colum n o f Table 310.15(B)(16) , th e minimu m siz e ser - vic e conductor s ar e 1/ 0 AW G copper. Table 250.66 requires a 6 AWG cop - per grounding electrode conductor for 1/0 servic e - entrance conductors. Reference: Table 250.66 10. Answer: 7314 volt - amperes. Heat = 6 (units) x 3000 (watts) = 18,000; [Four (or more) separately controlled, space heater s hav e a deman d facto r o f 40%. (220.30(C)(6)]; 18,000 x 40% = 7200 watts (volt - amp eres). A/C = 2 (units) x 10.5 (amperes) x 230 (volts) = 4830 volt - amperes; 3 (units) x 7.2 (amperes) x 115 (volts) = 2484 volt - amperes . Air - conditionin g loads hav e a deman d facto r o f 100% (220.30(C)(1) . T o tal air - conditioning load 4830 + 2484 = 7314 vol t - amperes. The air - conditioning load is larger than the heating load. Reference: 220.82(C) 11. Answer: 1500 Reference: 220.52(B) 12. Answer: 8000 Reference: Table 220.55 13. Answer: 145 amperes 14. Answer: 150 amperes 15. Answer: 1 AWG copper. Multiply the service rating by 83 percent [310.15(B)(7)(1)] 150 x 83% = 124.5 = 125 amperes. In accordance with the 75°C column of Table 310.15(B)(16), the ampacity of a 1 AWG copper conductor is 130 amperes. 16. Answer: 6 AWG copper 17. Answer: 114 a mperes 18. Answer: 125 amperes

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    1 General Lighting and Receptacle Loads 220.12 Do not include open porches, garages, or unused or 3 × = 1 unfinished spaces not adaptable for future use. (sq ft using outside dimensions) 2 Small-Appliance Branch-Circuits 220.52(A) At least two small-appliance branch circuits 1500 × = 2 must be included. 210.11(C)(1) (minimum of two) 3 Laundry Branch Circuit(s) 220.52(B) At least one laundry branch circuit 1500 × = 3 must be included. 210.11(C)(2) (minimum of one) 4 Add lines 1, 2, and 3 4 Lines 5 through 8 utilize the demand factors found in Table 220.42. 5 – 3000 = 5 6 – 117,000 = 6 (line 4) (if 117,000 or less, skip to line 8) (line 5, if more than 117,000) 7 × 25% = 7 8 × 35% = 8 (line 6) (smaller of line 5 or 117,000) 9 Total General Lighting and Receptacle Load 3000 + + = 9 (line 7) (line 8) 10 Fastened-In-Place Appliances 220.53 Use the nameplate rating. Do not include electric ranges, clothes dryers, space-heating equipment, or air-conditioning equipment. If fewer than four units, put total volt-amperes on line 10. × 75% = 10 If four or more units, multiply total volt-amperes by 75%. (volt-amps of four or more) 11 Clothes Dryers 220.54 (If present; otherwise skip to line 12.) Use 5000 watts or the nameplate rating, whichever is larger. 11 The neutral demand load is 70% for feeders. 220.61(B) 12 Ranges, Ovens, Cooktops, and Other Household Cooking Appliances Over 1750 Watts 220.55 (If present; otherwise skip to line 13.) Use Table 220.55 and all of the applicable Notes. 12 The neutral demand load is 70% for feeders. 220.61(B) 13 Heating or Air-Conditioning System (Compare the heat and A/C, and omit the smaller.) 220.60 Include the air handler when using either one. For heat pumps, include the compressor and the 13 maximum amount of electric heat that can be energized while the compressor is running. 14 Largest Motor (one motor only) 220.50 and 430.24 × 25% = Multiply the volt-amperes of the largest motor by 25%. (volt-amps of largest motor) 14 15 Total Volt-Ampere Demand Load: Add lines 9 through 14 to find the minimum required volt-amperes. 15 16 Minimum Amperes Divide the total 16 17 17 volt-amperes by ÷ = the voltage. (line 15) (voltage) (minimum amperes) 18 Size the Service or Feeder Conductors. Use 310.15(B)(7) to find the service conductors up to 400 amperes. Ratings in excess of 400 amperes shall comply with Table 310.15(B)(16). 18 310.15(B)(7) also applies to feeder conductors supplying the entire load. 19 Size the Neutral Conductor. 220.61 310.15(B)(7) states that the neutral service or feeder conductor can be smaller than the ungrounded (hot) conductors, provided the requirements of 215.2, 220.61, and 230.42 are met. 19 250.24(C)(1) states that the grounded conductor shall not be smaller than specified in Table 250.102(C)(1). 20 Size the Grounding Electrode Conductor (for Service). 250.66 Use line 18 to find the grounding electrode conductor in Table 250.66. Size the Equipment Grounding Conductor (for Feeder). 250.122 20 Use line 17 to find the equipment grounding conductor in Table 250.122. Equipment grounding conductor types are listed in 250.118. water heater / compactor / / dishwasher / / / disposer / / / Minimum Size Service or Feeder 240.6(A) Minimum Size Conductors Minimum Size Neutral Conductor Minimum Size Grounding Electrode Conductor Standard Method Load Calculation for One-Family Dwellings Unit 8 . . . Questions 13 through 16 2500 2 1 7500 12,000 12,000 9000 9000 ---- ---- 4000 1500 828 ---- 3/50 3/50 6328 5000 8000 76/3 1610 34,701 150 1 copper 6 copper 6440 34,701 240 145 6/50 3000 1500

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