National Electrical Code
PART 1: LOAD CALCULATION, SINGLE-FAMILY DWELLING 3
PART 2: RESIDENTIAL ROOM WIRING 6
PART 3: BRANCH CIRCUIT SIZING 12
PART 4: DETERMINING RECEPTACLE LOCATIONS 16
PART 5: NEC CODE VIOLATIONS 17
SUBMITTING YOUR WORK 22
National Electrical Code
INTRODUCTION This next portion of your program is a project-based assign- ment designed for you to demonstrate your understanding of the National Electrical Code and your ability to apply the requirements and their interpretations to some typical resi- dential building applications and one industrial application. As you have learned, the National Electrical Code (NEC) is a reference manual that outlines requirements for the instal- lation of electrical equipment. The NEC is published by the National Fire Protection Association (NFPA) and is updated every three years to reflect changes in the industry.
The exact requirements for the installation of electrical equip- ment in your area will vary depending on local regulations. You learned in your studies that the application of the Code is rarely an exact science and that the Authority Having Jurisdiction (AHJ) is often the final determination of local code compliance. However, almost all electrical requirements are based on the National Electrical Code. Therefore, it’s very important to understand the NEC thoroughly and be able to apply it to your work.
One objective of this project is to help you appreciate that you don’t to have to memorize the various NEC codes. You’ll be asked to use the NEC in the way that it was designed, as a rule book of sorts, that you will apply, step-by-step, through some interesting and challenging problems. All of the submis- sions for this assignment are open-book, so you can relax and focus on developing your skills in using the NEC.
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Before you begin, this is a good time to simply review the NEC and to locate the articles that you would expect to apply to common building projects. Familiarize yourself with the loca- tions of common applications in the codes, as you’ll need this information to complete this project. In this project, you’ll also be looking at electrical wiring diagrams. Therefore, you may also want to review the material on how to read these dia- grams before you begin this project.
Interpreting the floor plan wiring diagram for a typical res- idence, then carrying out the required wiring, is no simple matter. To remind you of the details which must often be addressed in a typical residential project, a wiring diagram was included with this portion of your program. The stand- alone drawing shows a complete wiring diagram for one floor of a typical residence. As you can see, this typical residence contains many electrical outlets and devices. All of these devices must be installed to satisfy NEC requirements. You should note that the stand-alone drawing isn’t a part of the actual assignments that you’ll complete; it’s simply a good practice tool to brush-up on your print-reading skills.
In this project, you’ll use your knowledge of the NEC to answer a variety of questions about electrical circuits. Because this is an application-type project that involves real- life scenarios, the project will take some time to complete. Using the NEC can be time consuming when you’re first learn- ing, so don’t become frustrated if this project takes a little longer to complete than you expected.
You can submit this project in one of two ways: (1) Print this project booklet, write your answers to the exercises inside the printout, and mail the booklet to the school along with the answer sheet found in the back. (2) Create a Word document of your answers, scan your marked up Figure 7, and upload your project on the student portal.
Throughout this project, you’ll be required to answer questions. In fact, there are a total of 40 questions (or combi- nations of questions) for you to answer, including two tables to be filled in, as well as an additional figure to be marked up. Grading of this project will be as follows:
• Questions 1 through 40 (except Question 11 and Question 40): 2 points each
• Question 11 (requires completion of Table 1): 5 points
• Markup of Figure 7: 10 points
• Question 40 (requires completion of Table 2): 5 points
Total Possible Score: 100 points
Now that you understand the basic goals of your project, let’s get started.
PART 1: LOAD CALCULATION, SINGLE-FAMILY DWELLING When an electrician installs the wiring in a new building, he or she often needs to determine the service amperage. To accurately determine the service amperage, the electrician must be able to calculate all of the various loads associated with general lighting circuits, small-appliance branch circuits, and fixed-appliance circuits that supply ranges, dryers, and HVAC systems. The NEC has specific guidelines for perform- ing these calculations.
In this exercise, you’ll use the Standard Method to perform the load calculations for a one-family residence. As you work through this exercise, please write out all of your calculations. To receive credit for the questions, you must show exactly how you arrived at each solution. (Use scrap paper for preliminary calculations, if you need to.)
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Building Electrical Specifications:
You’ll be required to determine specific circuit loads, the min- imum service, and related conductor sizes for a single-family home with the following electrical specifications:
• Building Size: 3,800 square feet (exclusive of an unfin- ished basement, not adaptable for future use, an unfinished attic, and open porches)
• Small Appliance Branch Circuits: 3
• Laundry Branch Circuits: 1
• Fastened-in-Place Appliances: Water heater (28 kVA), Dishwasher (1,200 VA), Food Disposal (1,200 VA), Attic Fans (2) @ 750 VA (1,500 VA total)
• Clothes Dryer: 5 kW
• Ranges, Ovens, Cooktops: Range 12 kW
• HVAC System: 3.5 Ton AC system 240 V, 17.9 A, Air handler 3.3 A
Question 1: Total General Lighting and Receptacle Load
Determine the total general lighting and receptacle load by calculating the general lighting load, the small-appliance branch circuit load, and the laundry branch circuit load. Apply any demand factor as applicable. Show your calcula- tions on the lines provided for Question 1 at the end of Part 1 of your project.
Question 2: Fixed-in-Place Appliance Load
Determine the total fixed-in-place appliance load. Show your calculations on the lines provided for Question 2 at the end of Part 1 of your project.
Question 3: Dryer Load
Determine the line and the neutral load for the dryer circuit in this residence. Show your calculations on the lines provided for Question 3 at the end of Part 1 of your project.
Question 4: Cooking Equipment Demand Load
Determine the line and the neutral load for the range in this residence. Show your calculations on the lines provided for Question 4 at the end of Part 1 of your project.
Question 5: HVAC Load
Determine the total AC load for the HVAC system in this residence. Show your calculations on the lines provided for Question 5 at the end of Part 1 of your project.
Question 6: Largest Motor Load
Determine the largest motor load for this residence. Do not consider the AC unit as a motor load. Show your calculations on the lines provided for Question 6 at the end of Part 1 of your project.
Question 7: Total Demand, Service Size and Service Conductors
Based on your calculations for questions 1–6, determine the total demand in VA for this residence, the minimum ser- vice size, and the minimum conductor sizes (THW) for the ungrounded and grounding electrode conductors (assume the neutral conductor to be the same as the ungrounded conductor). Show your calculations on the lines provided for Question 7 at the end of Part 1 of your project.
ANSWERS AND CALCULATIONS FOR PART 1 Answer to Question 1:
General Lighting and Receptacle Load: _______________________
Small-Appliance Branch Circuit Load: _______________________
Laundry Branch Circuit Load: _______________________________
Total General Lighting and Receptacle Load: _________________ _____________________________________________________________
Answer to Question 2:
Total Fixed-in-Place-Appliance Load: ________________________ _____________________________________________________________
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Answer to Question 3:
Dryer Demand Load: Line _____________ Neutral _____________
Answer to Question 4:
Cooking Equipment Demand Load: Line ______ Neutral ______
Answer to Question 5:
HVAC Demand Load ________________________________________
Answer to Question 6:
Largest Motor Demand Load ________________________________
Answer to Question 7:
Total Demand ______________________________________________
Minimum Service Size ______________________________________
Minimum Size Ungrounded Conductor ______________________
Minimum Size Grounding Electrode Conductor ______________ _____________________________________________________________
PART 2: RESIDENTIAL ROOM WIRING Now that you’ve completed your load calculations and deter- mined service size for a single-family dwelling, you’ll move to Part 2 of this project, which will examine the wiring require- ments for 3 basic residential room types: general living space (living rooms, dens, family rooms), a kitchen, and a bathroom.
General Living Space To begin Part 2 of your project, you’ll examine some general living space, one of the most basic wiring assignments in a home. Figure 1 illustrates some wiring that’s found in a typ- ical living room. Study this diagram carefully and review the NEC codes that apply to this type of room. Note that several outlets are shown in Figure 1. These outlets are typically used
for lighting and simple appliances, such as entertainment sys- tems and personal computers. The placement of the outlets in the room is important. Once you’ve reviewed the NEC articles that apply to this room, answer the following questions.
Question 8: Which article of the NEC describes the proper placement of outlets in this type of room?
Question 9: Part 1: According to the NEC, what is the maxi- mum wall space that’s allowed between two adjacent outlets? ____________ Part 2: How large must a wall space be to require an outlet? ____________ Part 3: Should an outlet located at 7-feet up the wall from the floor, used to power a light fixture, be included in wall space requirement _____________________________________________________________
Question 10: If the outlets in this room are supplied by a sin- gle 15A or 20A circuit, what is the maximum current that can be supplied (in amps) to a cord-and plug connected load?
FIGURE 1—Refer to this diagram while you’re working on questions related to the general living space
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Question 11: Look at the items listed in Table 1. Indicate which items are considered to be wall space by the NEC, and which items aren’t considered to be wall space. (Place an “X” in the appropriate column next to each item.)
Item Considered to Be
Not Considered to
Be Wall Space Fireplace Fixed glass panel Sliding segment of glass door Door opening Bar-type counter Wall space less than 1 foot wide Wall space 3 feet wide Doorway Fixed cabinet
Question 12: Part 1: In Figure 1, note that a switch is located close to the door. This switch operates an overhead light fix- ture. This arrangement is a requirement of the NEC. Which article of the NEC covers this regulation for a room of this type? ____________ Part 2: Other than the switch shown in Figure 1, what alternative way can be used to meet the NEC requirement? ____________
Question 13: If the branch circuits supplying the receptacles in the figure are rated at 20 A, what is the minimum ampacity rating of the conductors in the branch circuit?
Question 14: How many branch circuits that supply the room shown in Figure 1 are required to be GFCI protected accord- ing to the NEC?
Kitchen Now, you’ll apply your knowledge of the NEC to a simple kitchen layout. Figure 2 shows some wiring in a typical kitchen found in a single-family dwelling. Electrical circuits in kitchens supply current to small appliances, electric ranges, dishwashers, and refrigerators; as well as lighting and general branch-circuit outlets.
The NEC is very specific about the installation of wiring in kitchen areas. Study the wiring carefully in Figure 2 and look up the codes that apply to this situation in your NEC code- book. Then, answer the following questions.
FIGURE 2—Refer to this diagram when you’re working on questions related to the kitchen.
Question 15: What section of the NEC covers the use of GFCI- protected outlets in a residential kitchen?
Question 16: How many of the outlets shown in Figure 2 are required to be GFCI protected by the NEC? Identify the loca- tion of the outlets you selected on the figure.
Question 17: What is the maximum distance that can separate the two outlets located to the right of the sink in the figure?
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Question 18: The outlets along the countertop are to be used for small appliances. What is the minimum number of branch circuits that would be needed to supply just these small-appliance outlets?
Question 19: Part 1: What is the maximum distance (in feet) that the receptacle intended for the refrigerator can be from that appliance? ____________ Part 2: Name two common kitchen appliances that may require receptacle locations to be closer than required by 210.50 due to restrictions on cord lengths? ____________
Question 20: What is the minimum circuit protection (in amps) and wire size needed for each of the required small-appliance circuits?
Question 21: In Figure 2, note that an electrical outlet is shown on the island in the kitchen area. Is this outlet required by the NEC, or does it represent an NEC violation? Briefly explain your answer.
Question 22: Looking again at the island counter in the kitchen. If the countertop above the outlet was extended 12 inches beyond the base of the cabinet to allow bar-stool seat- ing at the counter, would that change the NEC status of the outlet? Briefly explain your answer.
Question 23: Suppose that a built-in dishwasher is to be installed in this kitchen. Does the NEC allow the dishwasher to be connected to the existing small-appliance circuits?
Question 24: Can any of the receptacles required for the coun- tertop space be mounted in the actual countertop? Cite an NEC section and condition to support your answer.
Question 25: Does the NEC allow the lighting circuit for a kitchen to be attached to the small-appliance circuits?
Question 26: What is the maximum height that the outlets on either side of the sink can be installed above the countertop surface?
Question 27: If the distance between the outlets on either side of the range in Figure 2 is less than 4 feet, are both outlets required per the NEC? Briefly explain your answer.
Bathroom You’ve worked through the general living area and the kitchen, and next you’ll look at the electrical wiring of a small residential bathroom. Figure 3 shows some wiring that’s to be installed in a bathroom. Study the wiring shown in the figure carefully, and review the NEC articles that apply in these situ- ations. Once you’ve reviewed the appropriate articles, answer the following questions about this wiring diagram.
FIGURE 3—Refer to this diagram while you’re working on questions related to the bathroom.
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Question 28: What section of the NEC covers the use of GFCI- protected outlets in a residential bathroom?
Question 29: How many of the outlets shown are required to be GFCI protected by the NEC? Circle your selections (if any) on Figure 3.
Question 30: In what situation would the NEC allow any one of the outlets in this bathroom to supply power to an outlet in another room?
Question 31: The receptacle near the basin in figure can be mounted on the countertop and, if a listed assembly, in the countertop. In what position may the receptacle not be mounted?
Question 32: Looking again at the receptacle near the basin. What is the maximum distance the outlet can be away from the outside edge of the basin?
Question 33: You’re rewiring the bathroom in Figure 3 as part of a remodeling project. The customer requests a GFCI receptacle on the back wall of the bathtub area, 5-feet from the top edge of the tub. Should you comply with the customer request? Site an NEC section to support your answer.
Question 34: Does the NEC allow the lighting circuit in the bathroom area to be connected to the same circuit as the out- let receptacles?
PART 3: BRANCH CIRCUIT SIZING You’ve had a chance to test your skills at load calculations and service sizing, as you’ve just completed your evaluation of some basic room wiring. The next important skill you’ll
practice is the proper sizing of the various branch circuits that feed specialized equipment such as ranges, and water heaters.
In Part 3 of your project, you’ll determine the proper size of the branch circuits for three wiring scenarios involving cook- ing equipment.
As you work through this exercise, please show all of your calculations on the calculation sheet at the end of Part 3. To receive credit for the questions, you must show exactly how you arrived at each solution. (Use scrap paper for preliminary calculations, if you need to, before you transfer your final cal- culations to the calculation sheet at the end of Part 3.)
Example 1: Suppose that you’re working in a home that has a 15 kW oven that operates on 240 V. The oven is on a branch circuit by itself, as shown in Figure 4.
15 kW OVEN
FIGURE 4—Diagram for Example 1
Question 35: What is the demand load for this circuit? (Show all of your calculations on the calculation sheet at the end of Part 3.)
Question 36: What size TW copper conductor should be used for the branch circuit? (Show all of your calculations on the calculation sheet at the end of Part 3.)
Example 2: Suppose that you’re working in a kitchen that contains one 8 kW counter-mounted cooking unit and two 6 kW wall-mounted ovens. All three appliances are served by the same 240 V branch circuit. This situation is illustrated in Figure 5.
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8 kW COOKTOP
6 kW OVEN
6 kW OVEN
FIGURE 5—Diagram for Example 2
Question 37: What would be the demand load for this branch circuit? (Show all of your calculations on the calculation sheet at the end of Part 3.)
Question 38: What is the minimum-size TW copper conductor that should be used for this branch circuit? (Show all of your calculations on the calculation sheet at the end of Part 3.)
Example 3: Suppose that you’re working in a building that contains commercial kitchen equipment. The kitchen contains three 3 kW ovens, a 20 kW water heater, and a 3 kW deep fryer, as shown in Figure 6.
20 kW OVEN 3 kW
OVEN 3 kW
OVEN 3 kW DEEP FRYER
FIGURE 6—Diagram for Example 3
Question 39: What would be the demand load for all of these items? (Show all of your calculations on the calculation sheet at the end of Part 3.)
ANSWERS AND CALCULATIONS FOR PART 3 Show all work for Part 3 here.
Answer to Question 35: _____________________________________
Show all calculations to determine the demand load for Question 35:
Answer to Question 36:
Show all calculations to determine the wire size for Question 36:
Answer to Question 37:
Show all calculations to determine the demand load for Question 37:
Answer to Question 38:
Show all calculations to determine the wire size for Question 38:
Answer to Question 39:
Show all calculations to determine the demand load for Question 39:
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PART 4: DETERMINING RECEPTACLE LOCATIONS In this exercise, you’ll evaluate the floor plan for general living space in a typical home and determine the proper locations for the electrical outlets in the room. The NEC covers not only the electrical wiring of devices, but also (in many cases) the proper location for each device.
Look at the living room shown in Figure 7. Imagine that you want to install in this room the minimum number of outlets required by the NEC. To complete the exercise, you’ll need to determine the minimum number of outlets needed for this room, and indicate the correct location where they should be installed in the room. You’ll mark the location of the outlets directly on Figure 7 in your project booklet.
To receive full credit for this exercise, you’ll need to do the fol- lowing four things:
1. Indicate the location of each outlet in the figure by using the appropriate symbol
2. Indicate the distance that the outlet should be placed along the adjoining wall
3. Show how the branch circuit(s) would be connected
4. Indicate the proper spacing between outlets to meet NEC code requirements
3 ft 3 ft
GLASS SLIDER GLASS FIXED
5 ft5 ft
FIGURE 7—Mark this diagram with receptacle locations and symbols.
Keep in mind that there are several different ways that this job can be done correctly. However, remember that you’re try- ing to install the minimum number of outlets. Therefore, you may have to try several different patterns to determine which configuration uses the minimum number of outlets. (Try sketching your ideas on scrap paper first; then, mark your final answers directly on Figure 7.)
PART 5: NEC CODE VIOLATIONS Part 5 of your NEC project will be similar to previous exercises in that you’ll be asked to evaluate simple electrical wiring dia- grams. However, these diagrams will contain NEC violations. It will be your job to locate and identify the code violations.
For example, suppose that you’re looking at a kitchen wiring diagram and notice that GFCI outlets weren’t placed near the sink. Well, the NEC requires that any outlet near water must be fitted with a GFCI outlet for protection from electrical
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shock. For the exercise, you would recognize that this instal- lation violates the NEC; you would then describe the violation and reference the article or section of the NEC that supports your answer.
The best approach to completing this exercise is to look over the illustrations in the project very carefully, paying attention to each and every detail. Then, use your knowledge of the NEC to check each circuit shown. Checking each circuit in an organized manner is the fastest and easiest way to complete the project.
Now, you’re ready to begin this part of your project. Carefully study the wiring diagrams shown in Figures 8 through 12.
At least one NEC violation is shown in each diagram. Identify each violation, and then describe the violation in Table 2. You’ll also need to indicate which article of the NEC is involved in the violation.
To be sure that you understand how this exercise works, one example has been completed for you in the table. Figure 8 shows a typical residential bathroom. As you can see in the figure, the outlet receptacle next to the basin isn’t GFCI protected. This is a violation of the NEC. (Article 210.8(A) (1) indicates that all electrical outlets in bathroom areas must have GFCI protection.) So, you would describe the problem as shown in the first line of Table 2.
Question 40: Review the figures, note all NEC violations
in each one, and determine which NEC article has been violated. Use this information to complete the remainder of Table 2.
FIGURE 8—Note any NEC violations in Table 2.
Table 2 Figure Number Description of NEC
Violated 8 Outlet not GFCI
protected Article 210.8(A)(1)
9 10 11 12
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14/2 15 A 120 V
8 ft 8 ft
8 ft8 ft
FIGURE 9—Note any NEC violations in Table 2.
12/2 20 A 120 V
FIGURE 10—Note any NEC violations in Table 2.
12/2 20 A 120 V
FIGURE 11—Note any NEC violations in Table 2.
3 ft 3 ft
3 ft 4 ft4 ft 4 ft
12/2 20 A 120 V 14/2
15 A 120 V
FIGURE 12—Note any NEC violations in Table 2.
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SUBMITTING YOUR WORK
Mail-In To mail-in your project, once you’ve completed all parts of this project and answered all of the questions, fill out your name and student number on the Answer Sheet on the following page. Then, using the address provided on the Answer Sheet, mail the entire lesson booklet to the school.
Be sure to keep a copy of your completed assignment!
Online You can also submit your graded project online:
1. On your computer, save a revised and corrected version of your project. Be sure to include your student number and exam number on your saved documents.
2. Go to http://www.pennfoster.edu and log in.
3. Go to your student portal.
4. Click on Take Exam next to the lesson you’re working on.
5. Enter your email address in the box provided. (Note: This information is required for online submission.)
6. Attach your file as follows:
a. Click on the Browse box.
b. Locate the file you wish to attach.
c. Double-click on the file.
d. Click on Upload File.
e. Repeat these steps for all documents.
7. Click on Submit Files.