94 Questions
According to Table 314.16(B)(1), how many volume allowances are required for each yoke or strap containing one or more devices or equipment?
Double volume allowance
What is the exception to omitting equipment grounding conductors or conductors smaller than 14 AWG from the calculations?
When they enter a box from a domed luminaire or similar canopy
How should the conductor fill be calculated?
All of the above
Which of the following is true about the clearance from the box wall to the installed device or equipment?
It should be at least 13 mm (1/2 in.)
According to the text, which side of a box is considered as the 'side' for the purpose of side-wiring entries?
Any wall other than the one opposite to the opening
What type of screws should be used for attaching covers or other equipment to the box?
Machine screws matching the thread gauge and size
Which type of wiring method requires the use of insulating bushings in metal boxes or conduit bodies?
Flexible tubing
What is the minimum distance that flexible tubing should extend inside the box or conduit body and beyond the end of any cable clamp?
1/4 inch
When using nonmetallic-sheathed cable with single gang nonmetallic boxes, what is the maximum distance that the cable should be fastened to the box?
200 mm (8 in.)
What is the maximum gap allowed between noncombustible surfaces and boxes employing a flush-type cover or faceplate?
3 mm (1/8 in.)
Which of the following is true about the total box volume and box fill?
The total box volume must be equal to the total box fill.
What is the volume allowance for each additional equipment grounding conductor that enters a box?
1/4
What is the maximum number of conductors permitted in conduit bodies enclosing 6 AWG conductors or smaller?
The maximum number permitted by Table 1 of Chapter 9.
What is required for conduit bodies to contain splices, taps, or devices?
They must be durably and legibly marked by the manufacturer with their volume.
Which of the following wiring methods is permitted to support a conduit body of any size, including a conduit body with only one conduit entry, as long as the trade size of the conduit body is not larger than the largest trade size of the conduit or tubing?
Intermediate metal conduit, IMC
Which of the following wiring methods is not permitted to support a box using locknuts and bushings?
Rigid metal conduit, RMC
What is the maximum size in cm3 (in.3) for an enclosure that contains a device(s) or supports a luminaire(s) and is supported by entering raceways?
1650 cm3 (100 in.3)
Under what conditions is an unbroken length of rigid or intermediate metal conduit permitted to support a box used for luminaire or lampholder support?
All of the above
According to the text, what is the maximum size for an enclosure that does not contain a device(s), luminaires, or lampholders and is supported by entering raceways?
100 in.3
According to the text, how should nails and screws secure boxes when used as a fastening means?
All of the above
According to the text, how should an enclosure mounted in a finished surface be secured?
All of the above
According to the text, how should an enclosure mounted to structural or supporting elements of a suspended ceiling be fastened in place?
All of the above
Which of the following is the minimum internal depth required for outlet boxes that do not enclose devices or utilization equipment?
12.7 mm (1/2 in.)
Which of the following is the minimum internal depth required for boxes that enclose devices or utilization equipment supplied by 12 or 10 AWG conductors?
23.8 mm (15/16 in.)
Which of the following is the minimum internal depth required for boxes that enclose devices or utilization equipment supplied by conductors larger than 4 AWG?
52.4 mm (21/16 in.)
Which of the following is the minimum internal depth required for boxes that enclose devices or utilization equipment supplied by 8, 6, or 4 AWG conductors?
30.2 mm (13/16 in.)
Which of the following is a requirement for boxes in electrical installations?
All of the above are requirements for boxes in electrical installations
Which of the following is NOT a suitable means of protecting boxes from corrosion?
Painting
Which of the following is a requirement for boxes and conduit bodies in electrical installations?
They must be accessible for wiring
Which of the following is true about the grounding requirements for metal covers or plates used in electrical equipment?
Metal covers or plates shall be connected to the equipment grounding conductor in accordance with 250.110.
What is the requirement for covering exposed combustible wall or ceiling finish between the edge of the luminaire canopy or pan and the outlet box?
The exposed combustible wall or ceiling finish shall be covered with noncombustible material if required by 410.23.
What is the requirement for flexible cord pendants passing through covers of outlet boxes and conduit bodies?
The covers shall be provided with identified bushings or shall have smooth, well-rounded surfaces on which the cords can bear.
According to the text, what is the minimum length of a pull box for straight pulls when the largest shielded or lead-covered conductor or cable entering the box has an outside diameter of $d$?
$48d$
According to the text, what is the minimum distance between each cable or conductor entry inside a pull box and the opposite wall of the box when the largest cable or conductor has an outside diameter of $d$?
$36d$
According to the text, what is the minimum distance between a cable or conductor entry and its exit from a pull box when the cable or conductor has an outside diameter of $d$?
$36d$
According to the text, what is the maximum weight that handhole enclosure covers should weigh in order to require the use of tools to open?
45 kg (100 lb)
Which of the following is true about the installation of power distribution blocks within a box?
Uninsulated live parts must be exposed within the box, regardless of the box cover
How should through conductors be arranged in relation to power distribution block terminals?
Unobstructed following installation
According to 314.29(A) and (B), how should boxes, conduit bodies, and handhole enclosures be installed?
In a way that wiring and devices contained in them can be rendered accessible
What is the exception for smaller openings in building surfaces that accommodate individual devices?
The branch circuit wiring is spliced in the box
Which of the following is true about outlet boxes used for the support of utilization equipment other than ceiling-suspended fans?
They must meet the requirements of 314.27(A) for the support of a luminaire that is the same size and weight.
What is the purpose of a weight-supporting attachment fitting (WSAF) in combination with a weight-supporting ceiling receptacle (WSCR)?
To support the weight of a luminaire or ceiling fan.
What is the minimum length required for a pull box in a straight pull with trade size 2 conduit?
16 inches
What is the minimum distance required between each raceway entry inside a box or conduit body and the opposite wall of the box or conduit body in angle or U pulls, or splices?
6 times the metric designator (trade size) of the largest raceway
According to the text, what is the minimum separation required between raceway entries enclosing the same conductor?
Six times the metric designator (trade size) of the larger raceway
According to the text, what is the maximum distance permitted between a wall and a removable cover when a raceway or cable entry is in the wall of a box or conduit body opposite the cover?
The distance required for one wire per terminal in Table 312.6(A)
According to the text, what is the minimum separation required between each raceway entry inside a box and the opposite wall of the box?
Six times the trade diameter of the largest raceway
According to the text, what is the minimum radius of the curve to the centerline required for listed conduit bodies of dimensions less than those required in 314.28(A)(2)?
As indicated in Table 2 of Chapter 9 for one-shot and full-shoe benders
Which of the following is true about outlet boxes used for supporting luminaires or lampholders?
Outlet boxes used for supporting luminaires or lampholders must be marked on the interior to indicate the maximum weight they can support if other than 23 kg (50 lb).
What is the maximum weight that an outlet box used for supporting a ceiling-suspended (paddle) fan can support?
32 kg (70 lb)
Which of the following is true about outlet boxes used for supporting ceiling-suspended (paddle) fans?
Outlet boxes used for supporting ceiling-suspended (paddle) fans must be listed and marked with the maximum weight they can support.
Which of the following is true about floor boxes used for receptacles located in the floor?
Floor boxes used for receptacles located in the floor must be listed specifically for this application.
According to the text, what is the maximum phase-to-phase voltage allowed for nonshielded, ozone-resistant insulated conductors in Type MC cables in industrial establishments where only qualified persons service the installation?
5000 volts
According to the text, what is the minimum voltage required for solid dielectric insulated conductors in permanent installations to have ozone-resistant insulation and be shielded?
2000 volts
According to the text, what should all metallic insulation shields be connected to?
A grounding electrode conductor or a grounding busbar
According to the text, what is the minimum metal thickness required for sheet steel used in constructing metal boxes over 1650 cm3 (100 in.3) in size?
1.35 mm (0.053 in.)
According to the text, what is the minimum thickness of insulating material required for metal covers that are not made of the same material as the box or conduit body?
0.79 mm (1/32 in.)
According to the text, what is the maximum operating temperature for medium voltage solid dielectric cables rated MV-105?
105°C
According to the text, when should type MV cable joints, cable terminations, and connectors be listed?
Effective January 1, 2026
Which of the following conditions permits the use of cables in industrial establishments?
Where the fault clearing time requirements of the 133 percent level category cannot be met
Which of the following conductor materials are permitted according to the text?
Aluminum and Copper-Clad Aluminum
What is the minimum size of conductors for a voltage rating of 15,001–28,000 volts?
1 AWG
How should conductors intended for use as ungrounded conductors be identified?
By the surface markings required by 315.16(B)(1)
Which of the following is a requirement for marking Type MV cable joints, cable terminations, and connectors?
The maximum rated voltage
According to the text, how should Type MV cable joints, terminations, or connectors be marked on the surface?
By using one or more of the methods described in 315.17(B)(1) or (B)(2)
According to the text, who should perform the installation and testing of Type MV cable?
A qualified person(s) with documented training and experience
According to the text, where is Type MV cable permitted to be installed?
In wet or dry locations, raceways, and cable trays
Which of the following is true about the thickness requirements for metal boxes and conduit bodies?
All of the above
According to the text, what is the requirement for covers of underground boxes that weigh over 45 kg (100 lb)?
All of the above
According to the text, what is the purpose of suitable covers for boxes?
To provide working space in accordance with 110.34.
Which type of cable joints and terminations are permitted for use on power systems rated up to and including 35,000 volts, nominal?
Type MV cable joints and terminations used where exposed to direct sunlight
What is the exception for nonshielded multiconductor cables rated 2001 volts to 2400 volts used for direct burial applications?
The cables are permitted if they have an overall metallic sheath or armor
How should Type MV cable terminated in equipment or installed in pull boxes or vaults be secured and supported?
By metallic or nonmetallic supports suitable to withstand the weight
What is the requirement for Type MV conductors and cables used for direct burial applications?
They should be shielded and identified for such use
Which of the following is a requirement for Type MV cable joints, terminations, or connectors?
They must be listed by a qualified testing laboratory
What is the maximum operating voltage for nonshielded insulated conductors listed by a qualified testing laboratory?
5000 volts
What is the primary purpose of shielding in electrical systems?
All of the above
According to the text, what is the maximum weight that handhole enclosure covers should weigh in order to require the use of tools to open?
50 pounds
According to the text, what is the minimum separation required between each raceway entry inside a box and the opposite wall of the box?
1/2 inch
According to the text, what is the minimum distance between a cable or conductor entry and its exit from a pull box when the cable or conductor has an outside diameter of $d$?
$2d$
According to the text, what is the maximum distance permitted between a wall and a removable cover when a raceway or cable entry is in the wall of a box or conduit body opposite the cover?
1 inch
According to Table 315.60(C)(15), what is the ampacity for a single insulated copper conductor of size 3/0 with a temperature rating of 105°C (221°F) and a voltage range of 5001-35,000 Volts?
What is the ampacity for a single insulated copper conductor of size 2 with a temperature rating of 90°C (194°F) and a voltage range of 2001-5000 Volts?
250
According to Table 315.60(C)(16), what is the ampacity for a single insulated copper conductor of size 6 with a temperature rating of 105°C (221°F) and a voltage range of 5001-35,000 Volts?
130
According to the text, what is the maximum burial depth to the top of direct-buried cables?
900 mm (36 in.)
According to the text, what is the minimum ambient earth temperature used for calculating ampacities?
20°C (68°F)
According to the text, what is the thermal resistance (Rho) used for calculating ampacities?
90
According to Table 315.60(C)(17), what is the ampacity for a single insulated aluminum conductor of size 2/0 with a temperature rating of 90°C (194°F) and a voltage range of 2001-5000 Volts?
According to Table 315.60(C)(17), what is the ampacity for a single insulated copper conductor of size 4 with a temperature rating of 90°C (194°F) and a voltage range of 5001-35,000 Volts?
130
According to Table 315.60(C)(17), what is the ampacity for a single insulated aluminum conductor of size 1/0 with a temperature rating of 105°C (221°F) and a voltage range of 2001-5000 Volts?
According to the text, when the burial depth of direct burial or electrical duct bank circuits is modified from the values shown in a figure or table, ampacities shall be permitted to be modified as indicated in 315.60(D)(2)(a) and (D)(2)(b). No ampacity adjustments shall be required where the burial depth is decreased. If burial depths are increased in part(s) of an electrical duct run, a decrease in ampacity of the conductors shall not be required, provided the total length of parts of the duct run increased in depth is less than 25 percent of the total run length. Where burial depths are deeper than shown in a specific underground ampacity table or figure, an ampacity derating factor of 6 percent per 300 mm (1 ft) increase in depth for all values of rho shall be permitted.
Ampacity adjustments are not required when the burial depth is decreased
According to the text, ampacities for ambient temperatures other than those specified in the ampacity tables shall be corrected in accordance with Table 315.60(D)(4) or shall be permitted to be calculated using the following equation: $I’ = I \cdot \left(\frac{Tc+234},{Ta+234}\right)$, where: $I’$ = ampacity corrected for ambient temperature, $I$ = ampacity shown in the table for $Tc$ and $Ta$, $Tc$ = temperature rating of conductor (°C), $Ta’$ = new ambient temperature (°C), $Ta$ = ambient temperature used in the table (°C).
Ampacities for ambient temperatures other than those specified in the ampacity tables shall be corrected using both Table 315.60(D)(4) and the equation $I’ = I \cdot \left(\frac{Tc+234},{Ta+234}\right)$
According to the text, ampacities for conductors and cables in air shall be as specified in Table 315.60(C)(1) through Table 315.60(C)(10). Ampacities shall be based on the following: (1) Conductor temperatures of 90°C (194°F) and 105°C (221°F), (2) Ambient air temperature of 40°C (104°F).
Ampacities for conductors and cables in air shall be based on conductor temperatures of 90°C (194°F) and 105°C (221°F)
According to the text, ampacities for conductors and cables in underground electrical ducts and direct buried in earth shall be as specified in Table 315.60(C)(11) through Table 315.60(C)(20).
Ampacities for conductors and cables in underground electrical ducts and direct buried in earth shall be based on the burial depth
Test your knowledge on luminaire installation requirements with this quiz. Learn about threaded joints, set-screws, and height specifications to ensure proper installation.
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