Solution and Answer Guide: Herman, Electrical Wiring Industrial, 19e, @2027, 979821433362;
Chapter 1: Plans and Sitework
Solution and Answer Guide
HERMAN, ELECTRICAL WIRING INDUSTRIAL , 19E, @2027, 9798214133362; CHAPTER 01: PLANS
AND SITEWORK
TABLE OF CONTENTS
Content Type.................................................................................................................1
Review Questions...................................................................................................................................... 1
CONTENT TYPE
REVIEW QUESTIONS
1. In a set of construction drawings, where would an electrician find information about the location and
placement of a building?
a. Answer: To find information about the location and placement of a building, the electrician
should examine the site plans.
2. From information on the composite site plan, where is the lowest area on the site and what is the elevation?
a. Answer: The southeast comer of the site is the lowest area, with an elevation of 745 ft.
3. What device is generally used to measure length on a plot or building plan?
a. Answer: A device called a scale is generally used to make measurements of building plans such
as an architect or engineer scale. For example, the footprint is measured as 5.3 in. long. The scale
is 50 ft per in.; thus, the length of the building is 5.3 in. 50 ft/ in. = 2.65 ft. In metric terms, the
scale would remain unchanged; i.e., 600:1. The footprint would measure 5.3 in. 25.4 mm/in. =
134.6 mm. The actual length would be 134.6 mm 600 = 80,760 mm. Checking the accuracy by
converting to feet, 80,760 mm/304.8 ft/mm = 265 ft.
4. What would be the elevation, at the pole, of the bottom of a trench being dug to install telephone, or data
service using nonmetallic conduit?
a. Answer: The original surface at the location of the telephone service pole can be assumed to be
at an elevation of 745.4 ft. The surface rise between the two contours (745 and 746) is 1 ft in a
distance of 100 ft (2 in. on the plans). The pole is approximately four-tenths of the distance from
the south contour; thus, the surface would rise 0.4 ft. The top of the pipe must be at least 18 in.
(1.5 ft) (450 mm) below grade according to NEC Table 300.5. Adding a generous 3 in. (0.25 ft)
(75 mm) for the size 2 conduit would give the minimum elevation for the bottom of the trench. At
the pole, the elevation of the bottom of the trench should be: 745 ft + 0.4 ft – 1.5 ft – 0.25 ft =
743.65 ft or less.
5. Which of the methods for measuring ground resistance is used to measure resistance over a wide area?
© 2027 Cengage Learning, Inc. All Rights Reserved. May not be scanned, copied or duplicated, or posted to a publicly 1
accessible website, in whole or in part.
, Solution and Answer Guide: Herman, Electrical Wiring Industrial, 19e, @2027, 979821433362;
Chapter 1: Plans and Sitework
a. Answer: The Wenner four-point test measures ground resistance over a wide area. It utilizes
four ground rods driven in the earth equally spaced apart.
6. What is the difference, is SI unit, between the lowest and the highest contours?
a. Answer: The lowest contour is 745 ft and the highest is 751 ft. The difference is 751 – 745 = 6
ft. In SI units this is 6 ft 0.3048 m/ft = 1.8288 m (1828.8 mm).
Note: To answer the following questions, examine the composite site plan, the north and west elevations, the site
plan symbols, and the NEC
7. What is the elevation of the manhole rim where the benchmark is established?
a. Answer: The elevation of the manhole rim is 745.68 ft, taken directly from plans, in the upper
left comer (BM 745.68 MH RIM).
8. What is the elevation of the first floor of the industrial building?
a. Answer: The elevation of the first floor of the industrial building is 751.5 ft, taken from north
elevation, west elevation, or from under the building name in the center of the building.
9. What is the vertical distance from the manhole rim to the first floor of the industrial building? (Measure in
decimal feet.)
a. Answer: The first floor of the industrial building is 5.82 ft (1.77 m) above the manhole rim
(751.5 – 745.68 = 5.82 ft).
10. What is the vertical distance from the manhole rim to the first floor of the industrial building, measured in
feet and inches accurate to 1⁄16 inch?
a. Answer: The first floor of the industrial building is 5 ft 9 and 13/16 in. (1.773 m) above the
manhole rim. From the previous question, the first floor is 5.82 ft above the bench mark (12 in. per
ft 0.82 ft = 9.84 in. 16 segments/in. 0.84 in. = 13.44 segments or 13/16 in.).
11. Where is the preferred area for location of the construction trailer? Why did you choose that area?
a. Answer: The preferred location would be along the east property line at the north end of the
property. The original contours are to remain; thus no grading will take place. A trailer located
there would not need to be relocated.
12. It was determined that the rigid nonmetallic conduit for the telephone service could be installed in a trench
with a bottom elevation of 743.65 ft. If the conduit is allowed to rise a distance of 1 ft, how deep is the
trench at the building?
a. Answer: If the conduit were to rise 1 ft from the pole, the bottom would be at 744.65 ft (743.65
ft + 1 ft = 744.65 ft).
13. Refer to plan E1 on page 2 of the plans. What is the height of the boiler room floor?
a. Answer: The height of the boiler room floor is 732.5 ft.
14. A cable containing two insulated conductors and a bare grounding wire is installed to a lighting standard
mounted on a base similar to the one shown in Figure 1-22. Assume you are the electrician in charge. What
instruction would you give to a first year apprentice who will make up the grounding connection?
© 2027 Cengage Learning, Inc. All Rights Reserved. May not be scanned, copied or duplicated, or posted to a publicly 2
accessible website, in whole or in part.
, Solution and Answer Guide: Herman, Electrical Wiring Industrial, 19e, @2027, 979821433362;
Chapter 1: Plans and Sitework
a. Answer: A cable containing two insulated conductors and a bare grounding wire is installed to a
lighting standard mounted on a base similar to the one shown in Figure 1-23. The grounding wire
should be connected to all of the metal parts of the standard and its base, which includes
connecting to the metal conduits, the anchor bolts, and the wire to the ground rod. If the standard
base is metal, the bolts would not need to be individually connected. (Note NEC 250.110.)
15. Why is it necessary to have a good grounding system for the building?
a. Answer: Proper grounding helps protect against transient currents, electrical noise, and
lightning strikes.
16. What are the three most common methods of determining ground resistance?
a. Answer: The three most common methods for determining ground resistance are:
i. the Wenner four-point method;
ii. the three-point fall-of-potential test; and
iii. the clamp-on ground resistance test.
17. Explain the difference between a soft metric conversion and a hard metric conversion.
a. Answer: Soft Metric Conversion: dimensions of a product already designed and manufactured
to the English system have their dimensions converted to SI metric dimensions. The product does
not change in size. Hard Metric Conversion: an existing product is redesigned into a new size.
© 2027 Cengage Learning, Inc. All Rights Reserved. May not be scanned, copied or duplicated, or posted to a publicly 3
accessible website, in whole or in part.
, Solution and Answer Guide: Herman, Electrical Wiring Industrial, 19e, @2027, 979821433362;
Chapter 2: The Unit Substation
Solution and Answer Guide
HERMAN, ELECTRICAL WIRING INDUSTRIAL , 19E, @2027, C ORE 9798214133362; CHAPTER 02: THE
UNIT SUBSTATION
TABLE OF CONTENTS
Content Type.................................................................................................................1
Review Questions...................................................................................................................................... 1
CONTENT TYPE
REVIEW QUESTIONS
1. What is the available fault current on the secondary of a three-phase, 225-kVA, 480//208/120-volt
transformer with an impedance of 1.8%?
a. Answer:
i. I sec fla = (225 x 1000)/(1.732 x 208) = 625 A
ii. I sca = 625 / .018 = 34,722 A
2. What is the maximum standard size fuse permitted for a single-phase 25-kVA transformer with an
impedance of 4%, installed in any location, with a primary voltage of 4160 V?
a. Answer:
i. I pri = 25, = 6 A
ii. I fuse = 6 x 300% = 18 A
iii. Note 1 allows next standard size above
iv. Therefore, answer is a 20 A fuse
3. Explain the operation of ground detectors and identify the situation that would require their use.
a. Answer: Under certain conditions, if the secondary is ungrounded, that is, floating, then
detectors may be installed to detect inadvertent grounding. By connecting a lamp from each phase
to a common ground, the lamps will each light dimly until a ground occurs, then one of the lamps
will go out and the other two will become brighter.
4. Explain the reasoning for installation of the two meters.
a. Answer: A watt-hour meter and a VAR-hour meter are installed to measure the quantity of
electricity and the power factor. The wiring systems must be designed to carry the apparent power,
which is determined by the power factor. The lower the power factor the larger the required
capacity of the delivery and distribution systems in order to deliver the needed watts. As installing
the larger distribution system would be costly to the utility company, it requires the user to pay a
penalty for creating a low power factor. The VAR-hour meter detects and records the low power
factor.
© 2027 Cengage Learning, Inc. All Rights Reserved. May not be scanned, copied or duplicated, or posted to a publicly 1
accessible website, in whole or in part.
Chapter 1: Plans and Sitework
Solution and Answer Guide
HERMAN, ELECTRICAL WIRING INDUSTRIAL , 19E, @2027, 9798214133362; CHAPTER 01: PLANS
AND SITEWORK
TABLE OF CONTENTS
Content Type.................................................................................................................1
Review Questions...................................................................................................................................... 1
CONTENT TYPE
REVIEW QUESTIONS
1. In a set of construction drawings, where would an electrician find information about the location and
placement of a building?
a. Answer: To find information about the location and placement of a building, the electrician
should examine the site plans.
2. From information on the composite site plan, where is the lowest area on the site and what is the elevation?
a. Answer: The southeast comer of the site is the lowest area, with an elevation of 745 ft.
3. What device is generally used to measure length on a plot or building plan?
a. Answer: A device called a scale is generally used to make measurements of building plans such
as an architect or engineer scale. For example, the footprint is measured as 5.3 in. long. The scale
is 50 ft per in.; thus, the length of the building is 5.3 in. 50 ft/ in. = 2.65 ft. In metric terms, the
scale would remain unchanged; i.e., 600:1. The footprint would measure 5.3 in. 25.4 mm/in. =
134.6 mm. The actual length would be 134.6 mm 600 = 80,760 mm. Checking the accuracy by
converting to feet, 80,760 mm/304.8 ft/mm = 265 ft.
4. What would be the elevation, at the pole, of the bottom of a trench being dug to install telephone, or data
service using nonmetallic conduit?
a. Answer: The original surface at the location of the telephone service pole can be assumed to be
at an elevation of 745.4 ft. The surface rise between the two contours (745 and 746) is 1 ft in a
distance of 100 ft (2 in. on the plans). The pole is approximately four-tenths of the distance from
the south contour; thus, the surface would rise 0.4 ft. The top of the pipe must be at least 18 in.
(1.5 ft) (450 mm) below grade according to NEC Table 300.5. Adding a generous 3 in. (0.25 ft)
(75 mm) for the size 2 conduit would give the minimum elevation for the bottom of the trench. At
the pole, the elevation of the bottom of the trench should be: 745 ft + 0.4 ft – 1.5 ft – 0.25 ft =
743.65 ft or less.
5. Which of the methods for measuring ground resistance is used to measure resistance over a wide area?
© 2027 Cengage Learning, Inc. All Rights Reserved. May not be scanned, copied or duplicated, or posted to a publicly 1
accessible website, in whole or in part.
, Solution and Answer Guide: Herman, Electrical Wiring Industrial, 19e, @2027, 979821433362;
Chapter 1: Plans and Sitework
a. Answer: The Wenner four-point test measures ground resistance over a wide area. It utilizes
four ground rods driven in the earth equally spaced apart.
6. What is the difference, is SI unit, between the lowest and the highest contours?
a. Answer: The lowest contour is 745 ft and the highest is 751 ft. The difference is 751 – 745 = 6
ft. In SI units this is 6 ft 0.3048 m/ft = 1.8288 m (1828.8 mm).
Note: To answer the following questions, examine the composite site plan, the north and west elevations, the site
plan symbols, and the NEC
7. What is the elevation of the manhole rim where the benchmark is established?
a. Answer: The elevation of the manhole rim is 745.68 ft, taken directly from plans, in the upper
left comer (BM 745.68 MH RIM).
8. What is the elevation of the first floor of the industrial building?
a. Answer: The elevation of the first floor of the industrial building is 751.5 ft, taken from north
elevation, west elevation, or from under the building name in the center of the building.
9. What is the vertical distance from the manhole rim to the first floor of the industrial building? (Measure in
decimal feet.)
a. Answer: The first floor of the industrial building is 5.82 ft (1.77 m) above the manhole rim
(751.5 – 745.68 = 5.82 ft).
10. What is the vertical distance from the manhole rim to the first floor of the industrial building, measured in
feet and inches accurate to 1⁄16 inch?
a. Answer: The first floor of the industrial building is 5 ft 9 and 13/16 in. (1.773 m) above the
manhole rim. From the previous question, the first floor is 5.82 ft above the bench mark (12 in. per
ft 0.82 ft = 9.84 in. 16 segments/in. 0.84 in. = 13.44 segments or 13/16 in.).
11. Where is the preferred area for location of the construction trailer? Why did you choose that area?
a. Answer: The preferred location would be along the east property line at the north end of the
property. The original contours are to remain; thus no grading will take place. A trailer located
there would not need to be relocated.
12. It was determined that the rigid nonmetallic conduit for the telephone service could be installed in a trench
with a bottom elevation of 743.65 ft. If the conduit is allowed to rise a distance of 1 ft, how deep is the
trench at the building?
a. Answer: If the conduit were to rise 1 ft from the pole, the bottom would be at 744.65 ft (743.65
ft + 1 ft = 744.65 ft).
13. Refer to plan E1 on page 2 of the plans. What is the height of the boiler room floor?
a. Answer: The height of the boiler room floor is 732.5 ft.
14. A cable containing two insulated conductors and a bare grounding wire is installed to a lighting standard
mounted on a base similar to the one shown in Figure 1-22. Assume you are the electrician in charge. What
instruction would you give to a first year apprentice who will make up the grounding connection?
© 2027 Cengage Learning, Inc. All Rights Reserved. May not be scanned, copied or duplicated, or posted to a publicly 2
accessible website, in whole or in part.
, Solution and Answer Guide: Herman, Electrical Wiring Industrial, 19e, @2027, 979821433362;
Chapter 1: Plans and Sitework
a. Answer: A cable containing two insulated conductors and a bare grounding wire is installed to a
lighting standard mounted on a base similar to the one shown in Figure 1-23. The grounding wire
should be connected to all of the metal parts of the standard and its base, which includes
connecting to the metal conduits, the anchor bolts, and the wire to the ground rod. If the standard
base is metal, the bolts would not need to be individually connected. (Note NEC 250.110.)
15. Why is it necessary to have a good grounding system for the building?
a. Answer: Proper grounding helps protect against transient currents, electrical noise, and
lightning strikes.
16. What are the three most common methods of determining ground resistance?
a. Answer: The three most common methods for determining ground resistance are:
i. the Wenner four-point method;
ii. the three-point fall-of-potential test; and
iii. the clamp-on ground resistance test.
17. Explain the difference between a soft metric conversion and a hard metric conversion.
a. Answer: Soft Metric Conversion: dimensions of a product already designed and manufactured
to the English system have their dimensions converted to SI metric dimensions. The product does
not change in size. Hard Metric Conversion: an existing product is redesigned into a new size.
© 2027 Cengage Learning, Inc. All Rights Reserved. May not be scanned, copied or duplicated, or posted to a publicly 3
accessible website, in whole or in part.
, Solution and Answer Guide: Herman, Electrical Wiring Industrial, 19e, @2027, 979821433362;
Chapter 2: The Unit Substation
Solution and Answer Guide
HERMAN, ELECTRICAL WIRING INDUSTRIAL , 19E, @2027, C ORE 9798214133362; CHAPTER 02: THE
UNIT SUBSTATION
TABLE OF CONTENTS
Content Type.................................................................................................................1
Review Questions...................................................................................................................................... 1
CONTENT TYPE
REVIEW QUESTIONS
1. What is the available fault current on the secondary of a three-phase, 225-kVA, 480//208/120-volt
transformer with an impedance of 1.8%?
a. Answer:
i. I sec fla = (225 x 1000)/(1.732 x 208) = 625 A
ii. I sca = 625 / .018 = 34,722 A
2. What is the maximum standard size fuse permitted for a single-phase 25-kVA transformer with an
impedance of 4%, installed in any location, with a primary voltage of 4160 V?
a. Answer:
i. I pri = 25, = 6 A
ii. I fuse = 6 x 300% = 18 A
iii. Note 1 allows next standard size above
iv. Therefore, answer is a 20 A fuse
3. Explain the operation of ground detectors and identify the situation that would require their use.
a. Answer: Under certain conditions, if the secondary is ungrounded, that is, floating, then
detectors may be installed to detect inadvertent grounding. By connecting a lamp from each phase
to a common ground, the lamps will each light dimly until a ground occurs, then one of the lamps
will go out and the other two will become brighter.
4. Explain the reasoning for installation of the two meters.
a. Answer: A watt-hour meter and a VAR-hour meter are installed to measure the quantity of
electricity and the power factor. The wiring systems must be designed to carry the apparent power,
which is determined by the power factor. The lower the power factor the larger the required
capacity of the delivery and distribution systems in order to deliver the needed watts. As installing
the larger distribution system would be costly to the utility company, it requires the user to pay a
penalty for creating a low power factor. The VAR-hour meter detects and records the low power
factor.
© 2027 Cengage Learning, Inc. All Rights Reserved. May not be scanned, copied or duplicated, or posted to a publicly 1
accessible website, in whole or in part.
