Deck 10: Electrical Box Installation

Question 1

The NEC requires all device boxes installed to meet the requirements of Section 210.52 to be no higher than 5-1/2 feet but has no other rules regarding the mounting height of electrical boxes for switches or receptacles in residential wiring.

Answer 1

True

Question 2

The NEC requires that device boxes be installed so that all nails or screws are outside the box.

Answer 2

False
Nails or screws are permitted inside the box as long as they are no more than 1/4 inches from the top, bottom or sides of the box.If screws are used the sharp threads must be covered with a material that provides protection to conductor insulation inside the box.

Question 3

A device box or lighting outlet box can also be used as a junction box.

Answer 3

True

Question 4

The size of the opening of a standard metal device box used to mount a switch or receptacle in a wall is __________.

A) 2" * 4"
B) 2" * 2"
C) 4" *4"
D) 3"* 2"

Question 5

Ceiling-suspended paddle fans that weigh more than __________ pounds may be supported by an outlet box as long as the box has the maximum weight it can support marked on it.

A) 35
B) 40
C) 50
D) 55

Question 6

When installing electrical boxes above a dropped ceiling, it is OK to have the boxes supported by the same wires that hold up the dropped ceiling.

Question 7

__________ have no ears on them and are designed to be attached directly to building framing members.

A) Old-work boxes
B) New-work boxes
C) Re-model boxes
D) Fill boxes

Question 8

Electricians usually choose square boxes as junction boxes because they can contain more conductors than a comparable octagon box.

Question 9

When computing box fill, which of the following would count as one conductor?

A) Single-pole switch
B) External cable clamp
C) Duplex receptacle
D) None of the above

Question 10

Lighting fixtures that weigh more than __________ pounds must be supported independently of the outlet box.

A) 35
B) 40
C) 50
D) 55

Question 11

The number of conductors permitted in a box is determined by __________.

A) the area of the box
B) the perimeter of the box
C) the volume of the box
D) Underwriters Laboratories

Question 12

When computing box fill, each 14 AWG lighting fixture wire counts as one conductor.

Question 13

Nonmetallic device boxes used in residential wiring typically have both their cubic-inch volume and the maximum number of 14, 12, and 10 AWG conductors marked on the box.

Question 14

In walls or ceilings made of noncombustible materials, electrical boxes must be mounted so they are __________ the finished wall surface.

A) set back no more than 1/8 inch from
B) set back no more than 1/4 inch from
C) set back no more than 1/2 inch from
D) flush with

Question 15

Nonmetallic electrical boxes used for lighting outlets in residential wiring are usually __________.

A) rectangular
B) square
C) octagonal
D) round

Question 16

If a box has one or more securely installed barriers, the volume of the box must be apportioned to each of the resulting spaces.

Question 17

The volume for a pancake box is durably and legibly marked on the box by the box manufacturer.

Question 18

The NEC requires electrical boxes to be mounted so that they are flush with the finished surface of walls made of both combustible and noncombustible materials.

Question 19

A wire that has its origin inside a device box and does not leave the device box, such as a pigtail, counts as one conductor when computing box fill.

Question 20

In residential wiring, which of the following is an area where Handy (Utility) boxes would not be used?

A) Unfinished basements
B) Unfinished garages
C) Outdoors
D) Storage buildings

Question 21

A plastic nail-on single-gang device box has a volume of 24 cubic inches.What is the maximum number of 14 AWG conductors it can hold?

A) 12
B) 14
C) 18
D) 24

Question 22

Explain why lighting outlet boxes are permitted to be used as junction boxes.

Question 23

When computing box fill, all internal clamps count as ____________________ conductor(s) of the largest conductor in the box.

Question 24

A metal device box has two 14 AWG conductors, one 14 AWG grounding conductor, two internal clamps, and a duplex receptacle.What is the minimum size metal device box you could use?

A) 3 *2 * 2
B) 3* 2 * 2-1/4
C) 3 * 2 * 2-1/2
D) 3* 2 * 3-1/2

Question 25

When computing box fill, three equipment-grounding conductors are counted as ____________________ conductor(s) of the largest equipment-grounding conductor in the box.

Question 26

A metal 4" square box has ten 12 AWG conductors, four 12 AWG grounding conductors, and four external clamps.What is the minimum size 4" square box you could use?

A) 4 * 1-1/4
B) 4 * 1-1/2
C) 4 * 2-1/8
D) 4-11/16 * 1-1/4

Question 27

When computing box fill for a box that has more than one size of conductor in it, a 12 AWG conductor counts as __________ cubic inches.

A) 1.75
B) 2.0
C) 2.25
D) 2.5

Question 28

____________________ means capable of being removed or exposed without damaging the building structure or finish or not permanently closed in by the structure or finish of the building.

Question 29

A ____________________ saw is used to cut holes in lath and plaster or sheetrock walls when installing old work electrical boxes.

Question 30

When computing box fill, 3-12 AWG conductors and 2-14 AWG conductors would total __________ cubic inches.

A) 10.00
B) 10.25
C) 10.50
D) 10.75

Question 31

Each unspliced conductor that is less than 12 inches long running through a box is counted as ____________________ conductor when computing box fill.

Question 32

A 3"* 2" * 3-1/2" metal device box can hold a maximum of __________ 12 AWG conductors.

A) 10
B) 9
C) 8
D) 7

Question 33

When computing box fill, a duplex receptacle is counted as ____________________ conductors of the size conductor attached to it.

Question 34

A ____________________ is a short length of wire used in electrical boxes to make connections to device terminals.

Question 35

The actual volume for a 4" *1-1/2" square box with a 21-cubic-inch volume with a single gang 4"*3/4" raised plaster ring with a marked volume of 4.5 cubic inches attached to it is:

A) 18 cubic inches
B) 21 cubic inches
C) 25.5 cubic inches
D) 30.5 cubic inches

Question 36

The volume allowance for a 10 AWG conductor is ____________________ cubic inches.

Question 37

For each looped or coiled, unbroken length of conductor at least 12 inches long which passes through a box without splice or connection, the volume allowance is __________ of the actual conductor size.

A) 1
B) 2
C) 3
D) not counted

Question 38

A 4"* 1-1/2" square box can hold a maximum of __________ 14 AWG conductors.

A) 12
B) 10
C) 15
D) 9

Question 39

In which of the following NEC Tables would you find information on box fill?

A) Table 220.12
B) Table 314.16(A)
C) Table 250.66
D) Table 8 in Chapter 9

Question 40

Which of the following would count as two conductors when computing box fill?

A) Single-pole switch
B) Duplex receptacle
C) GFCI receptacle
D) All of the above

Question 41

Explain what "ganging" electrical boxes means.

Question 42

Explain what Madison hold-its are used for.

Question 43

Explain the importance of the air barrier of a house, how air sealing contributes to air tightness of a house, and the proper role of electric boxes that interact with the air barrier.

Question 44

Explain when an electrician would use an adjustable bar hanger to mount a ceiling electrical box.