Chapter 2 Review Electrical Wiring Residential 1k6155

Unit #2—Part 1 1.)

What does a plan show about electrical outlets? An architectural plan show the location and type of electrical device required. (pg.-20)

2.)

What is an outlet? An access point for an electrical device such as a receptacle outlet, switch outlet, or lighting outlet. (pg.-20)

3.)

Match the following switch types with the proper symbol. (pg. 24) a) single-pole Sp b) three-way S4 c) four-way S d) single-pole with pilot S3

4.)

The plans show dashed lines running between switches and various outlets. What do these dashed lines indicate? The dashed lines means those switches control a portion of the outlets that they go to. (pg.-24)

5.)

Why are dashed lines usually curved? The curved lines will not be mistaken for foundation or wall lines. (pg. 24)

6.)

a. What are junctions boxes used for? Junction boxes are used as for devices and lighting fixtures as well as protection wires and terminals. The boxes will contain the arch blast that could occur during a fault. (PG. 29) b. Are junction boxes normally used in wiring the first floor? Explain: When you have electrical outlets, appliance attachment or just the ing of wires together you must have a junction box that must be accessible, whether it is on the first floor or any where else. c. Are junction boxes normally used to wire exposed portions of the basement? Explain: Yes because exposed portion of the wiring below 8 feet are required to be protected from physical damage and boxes are required any where you have wires spliced.

7.)

How are standard sectional switch (device) boxes mounted? NEC 314.20 states that boxes must be mounted so that they will be set back not more than 1/4in. (6mm) in noncombustible walls or ceilings and flush when installed in combustible. (pg.-30)

8.)

a. What is an offset bar hanger? A bar that is offset to allow the box to set out a determined amount, the hanger also allows the box to be located away from the stud (pg.-27) b. What type of boxes may be used with offset bar hangers? Boxes that are designed to be used with the rated hanger, which means that they must be able to be attached to the offset bar hanger. The book shows a round fixture box but most any type of steel box could be used, but the set back may not be correct or may have to be adjusted for. (pg.-27)

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9.)

What methods may be used to mount luminaries (lighting fixtures) to an outlet box fastened to an offset bar hanger? The luminaries that weight less than 6-lbs maybe installed with 6-32 screws if it is wall mount and 8-32’s most any where else up to 50-lbs. Then special is needed for the box. (pg. 30)—NEC 314.27(A) and (B)

10.)

What advantage does a 4-in. octagon box have over a 3¼-in. octagon box? The additional size will allow a greater number of conductors to enter and exit the box. The depth of the box can also be greater with a 4-in. octagon box than a 3 ¼-in.

11.)

What is the size of the opening of a switch (device) box for a single device? The dimensions of a standard switch box is 2 in. x 3 in. (pg. 33)

12.)

The space between a door casing and a window casing is 3½ in. (88.9mm). Two switches are to be installed at this location. What type of switches will be used? A piggy-back switch, which means the switches are stacked in the same area as a single switch. A standard 2-gang square box requires 4 inches so you can only use a single-gang box. (pg. 34)

13.)

Three switches are mounted in a three-gang switch (device) box. The wall plate for this assembly is called a three-ganged cover plate.

14.)

The mounting holes in a device (switch) box are tapped for No. 6-32 screws. The mounting holes in a outlet box are tapped for No. 8-32 screws. The mounting holes in metal boxes for attaching equipment grounding conductors are tapped for 10-32 screws.

15.)

a.) How high above the finished floor in the living room are switches located? 46 in. (pg. 49) b.) How high above the garage floor are switches located? 46in.

16.)

a.) How high above the finished floor in the living room are receptacles located? 12in, (pg. 49)

17.)

Outdoor receptacle outlets in this dwelling are located 18 in. above grade. (pg. 49)

18.)

In the spaces provided, draw the correct symbol for each of the descriptions listed in (a) through (r).—NOT INCLUDED IN THE READING ASSIGNMENT

19.)

The front edge of a box installed in a combustible wall must be flush with the finished surface. (pg. 35)

20.)

List the maximum number of 12 AWG conductors permitted in a: (pg. 44—Table 314.16(A) a.) 4 in. x 1½ in. octagon box. ----------------6 b.) 4-11/16 in. x 1½ in. square box.-----------13 c.) 3 in. x 2 in. x 3½ in. device box. ----------8

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21.)

When a switch (device) box is nailed to a stud, and the nail runs through the box, the nails must not interfere with the wiring space. To accomplish this, keep the nail C (Select a, b, or c.) a) halfway between the front and rear of the box. b) a maximum of ¼ in. (6mm) from the front edge of the box. c) a maximum of ¼ in. (6mm) from the rear of the box. (pg. 36—NEC 314.23(B)(1))

22.)

Hanging a ceiling luminaire (fixture) directly from a plastic outlet box is permitted only if the box is rated for a luminaire and if it weighs less than 6 lbs. then 6-32 screws can be used.

23.)

It is necessary to count luminaire (fixture) wires when counting the permitted number of conductors in a box according to 314.16. (True) (False) The code states that for small equipment grounding conductors or not more than four conductors smaller than 14 AWG that originate form a luminaire (fixture) canopy or similar canopy (like a fan) and terminate in the box: Don’t count these…No additional volume required.

24.)

Table 314.16(A) allows a maximum of ten wires in a certain box. However, the box will have two cable clamps and one fixture stud in it. What is the maximum number of wires allowed in this box? Clamps—if a box contains one or more internal cable clamps: add a single-volume based on the largest conductor in the box. (1) Fixture Studs—if box contains one or more luminaire (fixture) studs or hickeys: add a singlevolume for each type based on the largest conductor in the box. (1) 10 wires – (1 for cable clamp & 1 for fixture stud or 2-total) = 8 wires max.

25.)

When laying out a job, the electrician will usually make a layout of the circuit, taking into consideration the best way to run the cables and /or conduits and how to make up the electrical connections. Doing this ahead of time, the electrician determines exactly how many conductors will be fed into each box. With experience, the electrician will probably select two or three sizes and types of boxes that will provide adequate space to “meet Code.” Table 314.16(A) of the Code shows the maximum number of conductors permitted in a given size box. In addition to counting the number of conductors that will be in the box, what is the additional volume that must be provided for the following items? Enter single or double volume allowance in the blank provided. a.) One or more internal cable clamps: single volume allowance. b.) For a fixture stud: single volume allowance. c.) For one or more wiring devices on one yoke: double volume allowance. d.) For one or more equipment grounding conductors: single volume allowance. (pg.-45)

26.)

Is it permissible to install a receptacle outlet above an electric baseboard heater? No, page 48 states that are not permitted to be located above an d electric baseboard heating unit.

27.)

What is the maximum weight of a luminaire (lighting fixture) permitted to be hung directly from an outlet box in a ceiling? 50 lbs. without the box having additional and the box must be designed for the weight, which means it would have to be listed for such an application. (pg. 30) NEC Section 314.27 (A) (B)

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28.)

Two 12/2 and two 14/2 nonmetallic-sheathed AWG cables enter a box. Each cable has an equipment grounding conductor. The 12 AWG conductors are connected to a receptacle. Two of the 14 AWG conductors are connected to a toggle switch. The other two 14 AWG conductors are spliced together since they serve as a switch loop. The box contains two cable clamps. Calculate the minimum cubic-inch volume required for the box. Answer: Ground Wire----#12 (2.25cu. in.)—1 x 2.25 ----------2.25 cu. in. Conductors: 2—#12/2 ---- 2 x 2 x 2.25 ------------------------------9.00 cu. in. 2—#14/2 ---- 2 x 2 x 2.00 ------------------------------8.00 cu. in. Devices: 1—toggle switch –1 x 2 x 2.25 ------------------------4.50 cu. in. 1—receptacle –1 x 2 x 2.25 ----------------------------4.50 cu. in. Fittings (clamps) 2—cable clamps—1 x 2.25 ----------------------------2.25 cu. in. ------------------------------------------------------------- 31.50 cu. in.

29.)

Using the same number and size of conductors as in questions 28, but using electrical metallic tubing, calculate the minimum cubic-inch volume required for the box. There will be no separate equipment grounding conductors, nor will there be any clamps in the box. Answer: Ground Wire—must figure on one ground wire due to the LOCAL CODE requirement of all conduit systems requiring a ground wire. The answers will be the same because the electrical metallic tubing will require the use of metallic connectors that must enter the box, you would count them as fittings, which means that no matter how many fittings are coming into the box the you will figure it at ( 1-times the cubic inch of the largest conductor that enters the box.

30.)

To allow for adequate conductor length at electrical outlet and device boxed to make up connections, 300.14 requires that not less than [ 3 in.(75 mm). 6 in. (150 mm), 9 in. (225 mm)] of conductor length be provided. This length is measured from where the conductor emerges from the cable or raceway to the end of the conductor. For box openings having any dimension less than 8in. (200mm), the minimum length of conductor measured form the box opening in the wall to the end of the conductor is [ 3 in. (75 mm), 6 in. (150 mm), 9 in. (225 mm). Circle the correct answer. Answer page 21 figure 2-2

31.)

When wiring a residence, what must be considered when installing wall boxes on both sides of a common partition that separates the garage and a habitable room? The fire rating of the walls must be maintained which means that boxes may not be mounted “back to back” or in the same air void. A separation of 24 inches horizontal must be maintained unless the boxes are listed as being fire resistant. The boxes that are on the fire rated wall must be properly protected or encased with a fire puddy.

32.)

Does the NEC® allow metal raceways to be used with nonmetallic boxes? Yes _____X______ No__________ NEC®______NEC® 314.3 (Exception) –previded that all metal raceways or cables entering the box are bonded together to maintanin the integrity of the grounding path to other equipment in the installation. P. 33

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