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Kansas Electrical Prep > Box and Raceway Sizing > Flashcards

Box and Raceway Sizing Flashcards

1
Q

True or False: When sizing boxes, conductors, clamps and support fittings are required to be counted in order to select the proper size box.

A

True.

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2
Q

True or False: Conductors that originate inside the box or that are spliced within the box are counted as one for each conductor.

A

False. Conductors that originate OUTSIDE the box or that are spliced within the box are counted as one for each conductor.

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3
Q

True or False: Conductors unbroken within the box, less than 12 inches in length, that pass through the box without splicing or terminating are counted as two for each conductor.

A

False: Conductors unbroken within the box, less than 12 inches in length, that pass through the box without splicing or terminating are counted as ONE for each conductor.

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4
Q

True and False: Conductors that originate within the box and do not leave the box such as bonding jumpers and pigtails are not counted

A

True.

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5
Q

True or False: Conductors from a domed luminaire (fixture) that terminate within the box are not counted.

A

True.

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6
Q

True or False: When sizing device and junction boxes, the insulation of the conductors are required to be taken into consideration.

A

False. They are NOT to be taken into consideration.

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7
Q

What volume (unit of measurement) is required for individual conductor(s)?

A

Cubic inches and or cubic centimeters, no matter what the insulation characteristics of the conductor(s) is/are

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8
Q

How do you determine the volume, in cubic inches, of a box?

A

Multiply length x width x depth of the box

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9
Q

A box measures 6 inches x 6 inches and is 4 inches deep. The volume is ______

A

144 cubic inches

6 x 6 x 4 = 144 cubic inches

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10
Q

What table # is used to determine the MIN size outlet box required for a given number of conductors, OR when determining the MAX number of conductors permitted in an outlet box when all conductors in the box are the SAME SIZE

A

314.16

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11
Q

Determine the MAX number of size 12 AWG THWN conductors permitted in a 4 x 1 1/2 in square box.

7
8
9
10

A

=9

The right hand side of the Table 314.16 under 12 column shows nine conductors permitted in the box

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12
Q

Of the following listed, which one of the boxes is the MIN required to house 3 size 12 AWG THWN/THHN conductors and 3 size 12 AWG conductors?

4 x 1 1/2 in octagon
4 x 2 1/4 in octagon
4 x 1 1/2 in square
4 x 2 1/4 in square

A

= 4 x 1 1/2 in octagon

Table 314.16

permits 6 size 12 AWG conductors in a 4 4 x 1 1/2 in octagon box

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13
Q

True or False: Table 314.16 shall apply where no fittings or devices, such as cable clamps, luminaire studs, hickeys, receptacles, switches or dimmers, are enclosed in the box.

A

True.

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14
Q

True or False: (Cable clamps) one or more internal cable clamps present in the box are counted as one conductor for each type of fitting, based on the largest conductor in the box.

A

True.

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15
Q

True or False: (Support fittings) One or more luminaire (fixture) studs and/or hickeys in the box are counted as one conductor for each type of fitting, based on the smallest conductor in the box.

A

False. Support fittings) One or more luminaire (fixture) studs and/or hickeys in the box are counted as one conductor for each type of fitting, based on the LARGEST conductor in the box.

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16
Q

True or False: (Devices) For each yoke or strap containing one or more device present in the box, they are to be counted as a single wire, based on the largest conductor connected to the device.

A

False. (Devices) For each yoke or strap containing one or more device present in the box, they are to be counted as TWO WIRES, based on the largest conductor connected to the device.

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17
Q

True or False: Equipment grounding conductors - one or more equipment grounding conductors or bonding jumpers contained in a box are to be counted as two conductors, based on the largest equipment grounding conductor or bonding jumper in the box.

**Where an additional set of isolated equipment grounding conductors are in the box, they are to be counted as one conductor, based on the largest equipment grounding conductor in the additional set.

A

False. Equipment grounding conductors - one or more equipment grounding conductors or bonding jumpers contained in a box are to be counted as ONE conductor, based on the largest equipment grounding conductor or bonding jumper in the box.

This is true:
**Where an additional set of isolated equipment grounding conductors are in the box, they are to be counted as one conductor, based on the largest equipment grounding conductor in the additional set.

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18
Q

A device box contains 2 internal clamps, 2 equipment grounding conductors, 1 bonding jumper, and one duplex receptacle. The number of conductors permitted in the box is to be reduced by _________ conductors.

3
4
5
6

A

=4

clamps: 1 wire
receptacle: 2 wires
equip.ground & bond wires 1 wire
= 4 wires

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19
Q

Determine which one of the following listed outlet boxes in the MIN size required to enclose the following conductors:

6 size 12 AWG conductors
2 size 14 AWG conductors
1 size 14 AWG equipment grounding conductors

4 x 1 1/2 in octagon
4 x 1 1/2 in square
4 x 2 1/4 in square
4 1/4 x 1 1/2 in square

A

= 4 x 1 1/2 in square

size 12 AWG = 2.25 cu. in. x 6
size 14 AWG = 2.00 cu. in. x 2
size 14 AWG equipment grounding x 1

3.5
4.0
+2.0
=19.5 cubic inches

Table 3.14
requires a 4 x 1 1/2 inch square box having a volume of 21 cubic inches.

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20
Q

True or False: Pull and junction boxes are to be sized by the raceway entering the box and NOT by the size of the conductors contained in the box when enclosing conductors of size 4 AWG or larger.

A

True.

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21
Q

True or False: In straight pulls, the length of the box shall not be less than ten times the trade diameter of the largest raceway entering the box.

A

False. In straight pulls, the length of the box shall not be less than EIGHT (8) times the trade diameter of the largest raceway entering the box.

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22
Q

Determine the MIN length of a pull box that has a trade size of 31/2 in. conduit entering at each end, and containing conductors of size 250 kcmil, when a straight pull of the conductors is to be made.

21 in
24 in
28 in
32 in

A

=28 in

3.5 in (conduit) x 8 = 28 inches

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23
Q

True or False: When splices, angle, and u pulls are made, the distance between each raceway entry inside the box and opposite wall of the box shall not be less than six times the trade size of the raceway in a row.

A

True.

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24
Q

True or False: For angle or U-pulls, the proper size junction box is determined by multiplying the largest raceway by eight and add any additional conduits.

A

False.
For angle or U-pulls, the proper size junction box is determined by multiplying the largest raceway by SIX (6) and add any additional conduits.

25
Q

A junction box is to be installed where the conductors are larger than size 4 AWG and angle 90 deg. pull of the conductors is to be made. 2 trade size 3 inch conduits are to enter the box from the top and 2 trade size 3 conduits are to enter the box from the side. Determine the MIN size pull box required.

36 in x 36 in.
27 in x 27 in.
24 in x 24 in.
21 in x 21 in.

A

= 21 in x 21 in

Top to bottom - 3 in (largest conduit) x 6 = 18in + 3 in = 21in

Side to side - 3in (largest conduit) x 6 = 18in +3 in = 21 in

26
Q

When determining the MAX number of conductors permitted for electrical conduit/tubing enclose conductors of the same size, within the same type of insulation, or when conduit/tubing is more 24 in. in length, what table is used?

A

Annex C, Tables C.1 through C.13

27
Q

Determine the MIN trade size electrical metallic tubing (EMT) more than 24 in. in length, permitted to enclose 12 size 10 AWG THWN conductors.

3/4 in
1 in
1 1/4 in
1 1/2 in

A

= 1 inch

First locate Table C.1 Annex C. Next refer to the type of insulation (THWN) of the conductors. Then, locate the wire size 10 AWG, and you will find for 12 size 10 AWG THWN conductors a trade size 1 in EMT is required.

28
Q

A trade size 1 1/2 in Schedule 40 PVC conduit, 25 feet in length, is permitted to enclose no more than ______ size 2 AWG XHHW compact aluminum conductors

6
7
8
10

A

=8

First locate Table C.11 and Annex C.
Next find the insulation type XHHW of the conductors.
Then locate the conduit size 1 1/2 in and conductor size 2 AWG and you will find a trade size 1 1/2 in Schedule 40 PVC is permitted to enclose 8 size 2 AWG XHHW compact aluminum conductors.

29
Q

When more than two conductors are installed in a trade size 2 in electrical metallic tubing (EMT) longer than 24 inches, the EMT has a allowable fill of ______.

  1. 013 square inches
  2. 778 square inches
  3. 040 square inches
  4. 324 square inches
A

=1.342 square inches

Under this condition in 2 in. EMT is permitted to have an allowable fill of 40 percent.

Table 4, Chapter 9

30
Q

When 4 current carrying conductors are installed in a trade size 2 inch electrical metallic tubing (EMT) nipple 18 inches long, the EMT has a MAX allowable fill of _____

  1. 013 square inches
  2. 778 square inches
  3. 040 square inches
  4. 324 square inches
A

=2.013

Under this condition the 2 in. EMT is permitted to have an allowable fill of 60%

Table 4, Chapter 9

31
Q

A size 8 AWG THWN copper conductor has an approximate area of ______.

.0437
.0366
.0835
.2160

A

= .0366 square inches

First, we locate the insulation (THWN) of the conductor.
Then, the size 8 AWG, and look to the extreme right side of the table to find the approximate area in square inches.
Table 5, Chapter 9

**This table shows the various sizes and insulators of conductors expressed in millimeters and sq.in. in accordance with appropriate diameter and area. In most cases, we relate to the approximate area in square inches…. on the right side of the table.

32
Q

What is the area, in square inches, of a size 3/0 AWG XHHW compact aluminum conductor.

.590 sq. in.
.2733 sq. in.
.2290 sq in.
.1885 sq. in.

A

.2290 sq. in.

First, from Table 5A of Chapter 9, locate the insulation XHHW of the conductor.
Then locate the wire size 3/0 AWG, and look und the in . 2

33
Q

The fastest and easiest method to determine the maximum number of conductors allowed in a standard trade size conduit or tubing is to use what table.

A

Chapter 9, table 1

34
Q

When looking for conduit/tubing enclose conductors of different sizes and/or insulations information can be found where (table)?

A

Chapter 9, table 4, 5, 5A

35
Q

Table 1 of Chapter 9 shows what information?

A

permitted fill, in % conduit/tubing, when 1-2 (+) conductors are installed in a conduit/tubing - they shall be permitted to be filled 40% of their cross sectional area.

36
Q

The maximum length not to exceed 24 inches between boxes and enclosures for conduit/tubing nipples, nipples shall be permitted to be filled to ______ % of their total cross-sectional area.

50
40
75
60

A

= 60

Chapter 9, Note 4

37
Q

How is table 4, Chapter 9 organized.
How is each type of conduit/tubing shown?
What is at the top of each table - the heading?
What is below that heading?
What is on the left side?

A

Each type of conduit/tubing is shown on its own separate table.

The top heading shows the INTERNAL diameter and % of fill

Below the top heading, shows the allowable fill of each size conduit/tubing expressed in in and millimeters.

The left side shows trade size and metric designator of the conduit/tubing

38
Q

A size 8 AWG solid bare equipment grounding conductor has an area of _____.

  1. 128 sq. in
  2. 146 sq. in.
  3. 017 sq. in.
  4. 013 sq. in.
A

=0.013

First, locate the wire size and standing properties from Table 8 of Chapter 9. Next, extend to the right under the in.2 heading to find the area.

** Conduits/tubing enclosing different size conductors and/or conductors having different insulations are sized by locating the area, in sq. in. of each conductor. Table 5, 5A, or 8 and multiplying by the # of conductors.

This total is used to select the proper size raceway in table 4, chapter 9.

39
Q

Determine the MIN trade size intermediate metal conduit (IMC) permitted to enclose three (3) size 8 AWG XHHW copper-branch circuit conductors and six (6) size 12 AWG THWN copper control - circuit conductors. The IMC is to be fifty (50) feet in length.

1/2 in
3/4 in
1 in
1 1/4 in

A

= 3/4 in.

8 x XHHW = . 0437 sq. in. x 3 conductors = .1311 sq. in.
12 x THWN = .0133 sq. in. x 6 conductors = .0798 sq. in.

= .2109 sq. in.

A trade size 3/4 in. IMC having an allowable fill @ 40% of
.235 square inches in the MINIMUM required.

40
Q

Determine the MINIMUM trade size, 1 foot long, rigid metal conduit (RMC) to enclose the following listed copper conductors.

4 - 3/0 AWG THWN
4 - 4/0 AWG THHN

3 in
2 in
3 1/2 in
2 1/2 in

A

= 2 1/2 inch

3/0 THWN= .2679 x 4 conductors = 1.0716 sq. in.
4/0 THHN= .3237 x 4 conductors =1.2948 sq. in.

=2.3664 sq. in.

A trade size 2 1/2 in RCM nipple having an allowable fill @ 60% of 2.919 square inches is the MIN required.

41
Q

What is the formula for determining the number of conductors, all of the same size, permitted in a conduit/tubing 24 inches or less in length?

A

Divide the allowable fill area of the conduit/tubing by the area of one conductor.

of conductors=Allowable fill area / area of conductor

42
Q

Determine the MAXIMUM number of size 2/0 AWG THHN copper conductors permitted to be installed in a trade size 2 in electrical metallic tubing (EMT) 18 inches long.

7
8
9
10

A

=9

2.013 sq in (allowable fill) /.2223 sq in (area of wire) = 9.05 or 9 wires

43
Q

True or False: When calculating the MAXIMUM number of conductors, all of the same size, permitted in a conduit or tubing, when the calculation results in a decimal of .8 or larger, as additional wire of the same size may be installed.

A

True

44
Q

Determine the MAXIMUM number of size 1/0 AWG THWN copper conductors permitted to be installed in a trade size 1 1/4 in rigid metal conduit (RMC) nipple.

4
5
6
7

A

=5

.916 sq. in (allowable fill) / .1855 sq. in. (area of wire) = 4.9 or 5 wires

45
Q

True or False. When calculating the number of conductors, all of the same size, permitted in a metal or nonmetallic wireway or an auxiliary gutter, the fill shall not exceed 50% or the interior cross-sectional area of the wireway or gutter where splices or taps are not made.

A

False. shall not exceed 20%

46
Q

Determine the MAXIMUM number of size 4/0 AWG XHHW copper conductors permitted to be installed in a 4in. x 4in. metal wireway.

10
11
20
16

A

=10

4in x 4in = 16in x 20% = 3.2 sq. in. permitted fill

3.2 sq. in (permitted fill) / .3197 sq. in. (area of wire) = 10 wires.

47
Q

When conductors are different sizes/ and or insulators, wireways and gutters can be properly sized by … ?(formula)

A

Dividing the total area, in square inches, of the conductors by the 20% permitted fill area, where splices or taps are not made.

Or, find the area (in sq.in.) of a specific wireway or gutter and multiply by 20% to find the allowable fill. Using this method you may have to try amore than one size gutter or wireway to find the proper size.

48
Q

A wireway is to contain the following listed conductors.

3- size 250 kcmil THHN compact aluminum
3 - size 4/0 AWG THHN compact aluminum
3 - size 1/0 AWG THHN compact aluminum

Which one of the following listed wireways is the MINIMUM size required to house the conductors?

4in x 4in
6in x 6in
8in x 8in
12in x 12in

A

=4in x 4in

Go to table 5A of Chapter 9 to determine the area of the conductors.

250 kcmil THHN compact AL =.3525 sqin x 3 = 1.0575
4/0 AWG THHN compact AL = .2780 sqin x 3 = .8340
1/0 AWG THHN compact AL= .1590 sqin x 3 = .4770
Total = 2.3685 sq.in.

2.3685 sq.in. (area of wires) = 11.8425 sq.in. required area/
20% (permitted fill)

A 4in x 4in. wireway with an area of 16 sq.in. is required

To cross-check:
4in x 4in = 16 sq.in. x 20% = 3.2 sq.in. allowable fill
This wireway having an allowable fill of 3.2 square inches may contain the conductors having an area of 2.3685 square inches.

49
Q

A 4 in x 1 1/2 in. octagon junction box with a flat blank cover may contain no more than _______ size 14 AWG conductors.

6
7
9
10

A

= 7

Table 314.16(A)

50
Q

A luminaire stud in a ceiling-mounted outlet box is considered an equivalent of _____ conductor(s).

1
2
3
none of these

A

= 1

314.16 (B) (3)

51
Q

When determining box fill, size 12 AWG THHN conductors are to be calculated at _______ for each conductor housed in the box.

  1. 75 cubic inches
  2. 00 cubic inches
  3. 25 cubic inches
  4. 50 cubic inches
A

= 2.25 cubic inches

Table 314.16 (B)

52
Q

For the purpose of determining conductor fill in a device box, a three way switch is counted as equal to ______ conductor(s), based on the largest conductor connected to the switch.

0
1
2
3

A

= 2

314.16 (B) (4)

53
Q

How many size 12/2 AWG with ground, nonmetallic sheathed cable(s) (NM) is/are permitted to be installed in a device box having a total volume of 18 cubic inches where a duplex receptacle outlet is in the box?

1
2
3
4

A

= 2

314.16 (B) (4)
Table 314.16 (B)

18 cu.in. (box) / 2.25 cu. in. (#12 wire) = 8 wires (allowable fill)

8 wires (allowable fill) - 2 (devices) = 6 wires may be added

12/2 with ground NM cable = 3 wires per cable

6 wires (allowed) / 3 wires (per cable) = 2 cables are permitted

54
Q

Determine the MINIMUM size trade size, fifty (50) foot long, intermediate metal conduit (IMC) permitted to enclose 4, size 8 AWG THWN copper branch circuit conductors.

1/2 in
3/4 in
1 in
1 1/4 in

A

=1 in

314.16 B (1), (2), (4), (5)

size 14/2 = 2.0 cu.in. x 4 = 8
size 12/2 = 2.25 cu.in. x 4 = 9
equip. grnd. = 2.25 cu.in. x 1 = 2.25
clamps = 2.25 cu.in. x 1 = 2.25
receptacle = 2.25 cu. in. x 2 =4.50
switch = 2.0 cu. in. x 2 = 4.0

Total = 30.00 cubic inches

**Note - one or more clamps are counted as equal to the largest wire in the box. One or more equipment grounding conductors are counted as equal to the largest equipment grounding conductor in the box. Devices are counted as equal to two (2) conductors, based on the largest wire connected to the device per. 314.16

55
Q

A two-gang device box is to contain two (2) size 12/2 AWG with ground nonmetallic sheathed (NM) cables connected to a duplex receptacle and two (2), size 14/2 AWG with ground NM cables connected to a single-pole switch. The device box will contain four (4) internal clamps. The two-gang box is required to have a volume of at least _____.

36 cubic inches
34 cubic inches
30 cubic inches
28 cubic inches

A

=36 cubic inches

Table 314.16 (A)

56
Q

A single-gang FS box is permitted to contain no more than ____ size 14 AWG THHN conductors.

6
7
8
9

A

=9

  1. 16 B(1)
  2. 25 cu. x 4 wires = 9 cubic inches
57
Q

Two (2) size 12 AWG conductors are looped inside a junction box so that there is more than 12 inches of free conductor. The conductors are not spliced and don not terminate on devices. What volume, in cubic inches, must be counted for the looped conductors?

  1. 25 cubic inches
  2. 75 cubic inches
  3. 50 cubic inches
  4. 0 cubic inches
A

=4.50 cubic inches

314.28 (A)

58
Q

When a pull-box is to contain conductors of size 4 AWG or larger and a straight pull of the conductors is to be made, the length of the box shall not be less than _______ times the trade size of the largest raceway entering the box.

6
4
8
none of these.

(pg114)

A

=6

Chapter 9, Table 1

Kansas Electrical Prep (6 decks)

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