National electrical code - determine the total general

Question

INTRODUCTION

This next portion of your program is a project-based assignment 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 residential building applications and one industrial application. As you have learned, the National Electrical Code (NEC) is a reference manual that outlines requirements for the installation 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.

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 performing 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.)

Building Electrical Specifications:

You'll be required to determine specific circuit loads, the minimum service, and related conductor sizes for a singlefamily 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 calculations 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 service 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.

PART 2: RESIDENTIAL ROOM WIRING

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 maximum 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 single 15A or 20A circuit, what is the maximum current that can be supplied (in amps) to a cord-and plug connected load?

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.)

Question 12: Part 1: In Figure 1, note that a switch is located close to the door. This switch operates an overhead light fixture. 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 according to the NEC?

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 location 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?

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 smallappliance 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 seating 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 countertop 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.

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 outlet receptacles?

PART 3: BRANCH CIRCUIT SIZING

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.)

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.)

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.)

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 following four things:

1. Indicate the location of each outlet in the figure by usingthe appropriate symbol

2. Indicate the distance that the outlet should be placedalong 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

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 diagrams. However, these diagrams will contain NEC violations. It will be your job to locate and identify the code violations.

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.

Refer Figures in attached file.

Attachment:- National Electrical.rar