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Electriciansparadise -- Still More Archived NEC Questions - 3


National Electrical Code Questions and Answers: Part 3
By David Herres

The National Electrical Code covers electrical installations in jurisdictions that have enacted it into law. Many workers assume that the Code covers installations of only over a certain voltage, but that is not the case. The Code covers all wiring, addressed from a perspective of electrical and fire safety.

Even wiring that does not involve hazardous voltage or power levels can be a fire hazard due to the fact that in the event of a fire, the insulation can contribute to the building's fire load and also generate a large quantity of toxic smoke.

While not a training manual for beginners, the Code is an invaluable reference for those involved in installation and design, both for power and light electricians and for cabling technicians.

Most state and municipal licensing exams focus on NEC content, and they are usually open book. This is a realistic approach because on the job, you would have a copy of the Code to consult. As a matter of fact, most of us could never memorize all Code requirements and stipulations. Whether you want to work efficiently onsite or at the drawing board, or score high on an electricians' exam, the best approach is not to attempt to memorize the numbers, but instead learn the overall structure of the Code so that you can look up any mandate quickly and accurately.

The following Code questions are approximately the same level of difficulty as found on many state electricians' licensing exams --

1. NEC defines an arc-fault circuit interrupter (AFCI) as a device intended to provide protection from the effects of faults by recognizing characteristics unique to arcing and by functioning to de-energize the circuit when an arc fault is detected.

A) True

B) False

Answer: A) True

The AFCI also functions as an over current device. The most common type is installed in a residential entrance panel in place of a standard circuit breaker.

2. AFCI's are required for all 120-volt, single-phase 15- and 20-amp branch circuits supplying outlets to dwelling unit

A) family rooms, dining rooms, living rooms and parlors.

B) libraries, dens, bedrooms and sunrooms.

C) recreation rooms, closets, hallways or similar.

D) All of the above.

Answer: D) All of the above.

GFCI's are required for applicable receptacles but AFCI's are required for applicable outlets including, for example, ceiling light fixtures and smoke detectors.

3. An exception allows AFCI protection to be omitted for a fire alarm system where the branch circuit supplying it is run in

A) Rigid Metal Conduit or Intermediate Metal Conduit.

B) Any of the above plus Electrical Metallic Tubing.

C) Any of the above plus Steel Armored Cable.

D) Any of the above plus Rigid Non-metallic Conduit.

Answer: C) Any of the above plus Steel Armored Cable.

This is to make sure that an over-zealous AFCI doesn't compromise a fire alarm system. Most installation make use of this exception.

4. Guest rooms and guest suites require AFCI protection if

A) There is permanent provision for cooking.

B) There is no sprinkler protection.

C) It is a commercial occupancy.

D) All wiring is in metal raceway.

Answer: A) There is permanent provision for cooking.

This is an example of increased usage mandated under NEC 2008.

5. Branch circuits supplying a continuous load must have an ampacity of ___ percent of that load.

A) 110

B) 125

C) 130

D) 150

Answer: B) 125.

This is before application of any adjustment or correction factors.

6. Factory installed receptacle outlets that are part of permanently installed electric baseboard heater units

A) May be counted toward required outlets for the wall space utilized by the heaters.

B) Are not to be connected to heater circuits.

C) Neither A nor B is true.

D) Both A and B are true.

Answer: D) Both A and B are True.

This type of installation is helpful in meeting required receptacle spacing in dwellings.

7. In every kitchen, family room, dining room, living room, parlor, library, den, sunroom, bedroom, recreation room or similar room of a dwelling unit, receptacles must be installed in any wall space so that no point is more than ___ feet from a receptacle.

A) 5

B) 6

C) 8

D) 12

Answer: B) 6

This minimum spacing does not apply to non-dwellings such as commercial and industrial buildings. In these occupancies, receptacle density and layout are up to the owner/designer.

8. Receptacles in floors are not counted toward this minimum requirement unless they are within ___ inches of the wall.

A) 12

B) 16

C) 18

D) 20

Answer: C) 18

The purpose of this requirement is to curtail overuse of extension cords.

9. In dwelling kitchens, which of the following statements is true?

A) Receptacles are required in each kitchen wall countertop that is 12" or wider.

B) Countertop receptacles must be installed so that no point along the wall is more than 24" from a receptacle.

C) Receptacles are not required behind a range, countertop-mounted cooking unit or sink.

D) All are true.

Answer: D) All are true.

These receptacles are to be GFCI protected.

10. In dwelling kitchens, at least one receptacle is required at each island countertop space with a long dimension of 24" or greater and a short dimension of 12" or greater.

A) True

B) False

Answer: A) True.

If either of these dimensions is less than stipulated, a receptacle is not required. A 22" X 22" island would not require a receptacle.

11. In dwelling unit bathrooms

A) One receptacle is required not less than three feet from the outside of each basin.

B) Two receptacles are required not less than three feet from the outside edge of each basing.

C) One receptacle is required not more than three feet from the outside edge of each basin.

D) Two receptacles are required not more than three feet from the outside edge of each basin.

Answer: C) One receptacle is required not more than three feet from the outside edge of each basin.

This receptacle must be GFCI protected.

12. For a one-family and each unit of a two-family dwelling that is at grade level

A) One receptacle outlet accessible while standing at grade level and located not more than 6 feet above grade level is required. B) One receptacle outlet accessible while standing at grade level and located not more than 6 feet above grade is required at the front and back of the dwelling.

C) One receptacle outlet accessible while standing at grade level and located not more than six feet above grade is required.

D) One receptacle outlet accessible while standing at grade level and located not more than six feet above grade is required at the front and back of the dwelling.

Answer: B) One receptacle outlet accessible while standing at grade level and located not more than 6 feet above grade is required at the front and back of the dwelling.

These receptacles are required to be GFCI protected.

13. Balconies, decks and porches that are accessible from inside the dwelling must have one receptacle. It must not be more than ___ feet above the surface.

A) 2

B) 4

C) 6

D) 6

Answer: D) 6

The purpose of this requirement is to eliminate the need for an extension cord brought through the doorway.

14. In laundry areas of dwellings, at least ___ receptacle(s) is (are) required.

A) 1

B) 2

C) 3

D) 4

Answer: A) 1

This is in addition to the 240-volt dryer receptacle. It is to be on a 20-amp small appliance circuit.

15. For a one-family dwelling, each basement, attached garage and detached garage with electric power must have at least ___ receptacle outlet (s).

A) 1

B) 2

C) 3

D) 4

Answer: A) 1.
This requirement prohibits a detached garage with lighting and/or electric overhead door operator but no receptacle outlets.

16. In dwelling units, hallways of ___ feet or more in length must have at least one receptacle.

A) 6

B) 8

C) 10

D) 12

Answer: C) 10.

Notice some requirements apply to one-family dwellings whereas others apply to all dwellings.

17. At least one receptacle is required within ___ inches of the top of a show window for every ___ feet measured horizontally.

A) 12, 10

B) 12, 12

C) 18, 12

D) 20, 16

Answer: C) 18, 12.

Like all NEC requirements, this is a minimum.

18. A 125- volt, single-phase, 15- or 20-amp receptacle is required at an accessible location for servicing heating, air-conditioning and refrigeration equipment. It must be on the same level and within ___ feet of the equipment.

A) 15

B) 25

C) 30

D) 35

Answer: B) 25.

The receptacle must not be connected to the load side of the equipment disconnecting means.

19. In dwelling units, at least one wall switch-controlled lighting outlet is required in every

A) living room.

B) bedroom.

C) kitchen.

D) habitable room and bathroom.

Answer: D) habitable room and bathroom.

This is usually a ceiling light fixture.

20. In dwelling units, at least one wall switch-controlled lighting outlet is required in each

A) hallway.

B) stairway.

C) attached garage or detached garage with electric power.

D) All of the above.

Answer: D) All of the above.

The hallways and stairways usually require two three-way switches.

21. For dwelling units, in attached garages and detached garages with electric power, there must be at least one wall switch-controlled lighting outlet to provide illumination on the exterior side of outdoor entrances or exits with grade level access. A vehicle door in a garage is not considered an outdoor entrance or exit.

A) True.

B) False.

Answer: A) True.

Such wiring and fixtures must be appropriate for whatever environmental conditions exist.

22. A feeder is NEC defined as all current conductors between the service equipment, the source of a separately derived system or other power supply source and the

A) final branch-circuit over current device.

B) load.

C) switching device.

D) Any of these.

Answer) A) final branch-circuit over current device.

A feeder has an over current device at each end.

23. Conductor size for feeders is calculated in Parts III, IV and V of Article 220 along with services and branch circuits.

A) True

B) False

Answer: A) True.

This article also contains information for permitted derating due to load diversity.

24. The minimum feeder circuit conductor size before the application of any adjustment or correction factors is not less than the non-continuous load plus ___ percent of the continuous load.

A) 110

B) 115

C) 125

D) 135

Answer: C) 125

A continuous load is one that is expected to remain on line for three or more hours.

25. The feeder conductor ampacity may not be less than that of the service conductors where the feeder conductors carry the total load supplied by service conductors with an ampacity of ___ amps or less.

A) 20

B) 30

C) 55

D) 100

Answer: C) 55.

In a large building it is sometimes more economical to run a feeder to a remote load center rather than to run numerous branch circuits.

26. For purposes of calculating branch-circuit and feeder loads, which of the following voltages are used?

A) 120, 120/240, 208Y/120

B) 240, 347, 480Y/277

C) 480, 600Y/347, 600

D) All of the above

Answer: D) All of the above

These are nominal voltages. Actual values may vary depending on utility specifications and location on the line.

27. Table 220.12 provides general lighting loads by occupancy. What is the load in volt-amperes per square foot for an office building?

A) 2

B) 3

C) 3

D) 4

Answer: 3

28. For dwelling units, the three volt-ampere per square foot general lighting load includes receptacles.

A) True

B) False

Answer: A) True

For dwelling units the receptacle load does not have to be figured separately.

29. For non-dwelling units, the general lighting load includes receptacles.

A) True

B) False

Answer: B) False

For non-dwellings, the receptacle load has to be figured separately.

-- END --

Books for electricians --

Here is a selection of the most significant electricians' books available online today, at the best prices around. Clicking on any logo provides access to reviews and ratings by electricians. A good place to start is with the 2008 NEC Handbook, which contains the complete text of the current code plus extensive commentary, diagrams and illustrations. Other books of interest for the electrician are available as well.

Low Voltage, Telecom, Fire Alarm Books --


HOME | Best Web Host | Question of the Week | Archived Questions | More Archived NEC Questions | Still More Archived Questions | Still More Archived Questions-2 | Still More Archived Questions-3 | Articles | Electrical Deficiencies | More Electrical Deficiencies | Electricians Tools | Online computers | Cybercorner | Electrician's License | Electronics Tutorials | Electricians' worksaving ideas | Electronic Theorems | Satellite Dish | Digital Cameras and Equipment | HTML Color Chart | Electronic Acronyms | Electronic Definitions | Electrician's Soldering Tutorial | Photovoltaic Power | Wind Power | Fire Alarm Basics | More Fire Alarm Info | Working with MC and EMT | Electricians' Color Code | Wiring Commercial Garages | Managing Your Emergency Lights | Lighting Design | Industrial Wiring | Wiring Ethernet | Residential Wiring | Low Voltage Wiring | PLC Overview | Electrical Troubleshooting Techniques | Using Loop Impedance Meter | Ten Common Grounding Errors |NEC and Low-Voltage Wiring | Raceway Protection and NEC | Working with Metal Raceway | Inductance and Characteristic Impedance | Understanding Capacitance | History of the Ethernet | Twisting Data Conductors | NEC Article 800, Communications Circuits | NEC Article 810, Radio and Television Equipment | NEC Article 820, Community Antenna and Radio Distribution Equipment | NEC Article 830, Network-Powered Broadband | Troubleshooting Submersible Well Pumps | Wiring Healthcare Facilities | First Edition National Electrical Code 1897 | Books for Electricians | Links



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