Question 1

________are used to minimize the passage of gas and to prevent the passage of flame through the conduit.

Accepted Answer

A)   Outlet boxes
B)   Seals
C)   Fibers
D)   Vacuums

Question 2

As a general rule, equipment installed in a Class II location must be ________.

Accepted Answer

A)   dustproof
B)   explosionproof
C)   waterproof
D)   dust-ignitionproof

Question 3

To help prevent condensation, some vertical seals are designed with________ .

Accepted Answer

A)   fiber dams
B)   conductors
C)   drain plugs
D)   horizontal seals

Question 4

Describe the mating surfaces of explosionproof equipment.

Accepted Answer

Great care must be exercised when instal...

Question 5

When horizontal seals are installed,________fiber dams must be used.

Accepted Answer

A)   two
B)   three
C)   four
D)   five

Question 6

Some types of explosionproof enclosures are designed to be drilled and tapped in the field. When this is done, at least________ full threads should be engaged between the conduit and the enclosure.

Accepted Answer

A)   three
B)   five
C)   seven
D)   11 B

Question 7

What is the difference between Division 1 and Division 2 hazardous locations?

Accepted Answer

Hazardous locations are divided into two...

Question 8

A Group A atmosphere contains________ .

Accepted Answer

A)   hydrogen
B)   2-butanol
C)   butadiene
D)   acetylene D

Question 9

________locations are considered to be the most hazardous.

Accepted Answer

A)   Class I, Division 1
B)   Class I, Division 2
C)   Class II, Division 1
D)   Class II, Division 2 A

Question 10

A Group E atmosphere contains ________.

Accepted Answer

A)   combustible metal dusts
B)   carbonaceous dusts
C)   acetaldehyde
D)   propylene oxide

Question 11

If it is necessary to remove a substance from the surface of an explosionproof enclosure that cannot be cleaned with solvent, use________ .

Accepted Answer

A)   a chisel
B)   a putty knife
C)   sandpaper
D)   a fine steel wool

Question 12

When circuit breakers are installed in Class I locations, they must be________ .

Accepted Answer

A)   dustproof
B)   dust-ignitionproof
C)   explosionproof
D)   waterproof

Question 13

What is the hazard level of an aircraft hangar?

Accepted Answer

NEC 513.1 defines an aircraft hangar as ...

Question 14

What do Group C and D atmospheres encompass?

Accepted Answer

Group C contains flammable gas or flamma...

Question 15

What conditions are required for flexible cords and attachment plugs to be used in hazardous areas?

Accepted Answer

When they are used, they must comply wit...

Question 16

Intrinsically safe equipment and circuits operate________ .

Accepted Answer

A)   without electricity
B)   at low power levels
C)   at high voltage
D)   at high current

Question 17

If a stem is longer than________in., lateral braces must be placed within 12 in. (300 mm)  of the luminaire, or an explosionproof flexible coupling must be used within 12 in. (300 mm)  of the junction box.

Accepted Answer

A)   6
B)   10
C)   12
D)   14

Question 18

The________ rating indicates the maximum operating temperature of a luminaire.

Accepted Answer

A)   T
B)   MOT
C)   MT
D)   TEMP

Question 19

Class III locations are areas that contain combustible________ .

Accepted Answer

A)   dusts
B)   gases
C)   fibers
D)   vapors

Question 20

In general, the floor area of a garage, up to a level of 18 in. (450 mm)  above the floor, is considered to be a________ location.

Accepted Answer

A)   Class I, Division 1
B)   Class I, Division 2
C)   Class II, Division 1
D)   Class II, Division 2

Exam 20: Hazardous Locations

________are used to minimize the passage of gas and to prevent the passage of flame through the conduit.

Correct AnswerverifiedShow Answer

As a general rule, equipment installed in a Class II location must be ________.

Correct AnswerverifiedShow Answer

To help prevent condensation, some vertical seals are designed with________ .

Correct AnswerverifiedShow Answer

Describe the mating surfaces of explosionproof equipment.

Correct AnswerverifiedGreat care must be exercised when instal...View AnswerShow Answer

When horizontal seals are installed,________fiber dams must be used.

Correct AnswerverifiedShow Answer

Some types of explosionproof enclosures are designed to be drilled and tapped in the field. When this is done, at least________ full threads should be engaged between the conduit and the enclosure.

Correct AnswerverifiedB

What is the difference between Division 1 and Division 2 hazardous locations?

Correct AnswerverifiedHazardous locations are divided into two...View AnswerShow Answer

A Group A atmosphere contains________ .

Correct AnswerverifiedD

________locations are considered to be the most hazardous.

Correct AnswerverifiedA

A Group E atmosphere contains ________.

Correct AnswerverifiedShow Answer

If it is necessary to remove a substance from the surface of an explosionproof enclosure that cannot be cleaned with solvent, use________ .

Correct AnswerverifiedShow Answer

When circuit breakers are installed in Class I locations, they must be________ .

Correct AnswerverifiedShow Answer

What is the hazard level of an aircraft hangar?

Correct AnswerverifiedNEC 513.1 defines an aircraft hangar as ...View AnswerShow Answer

What do Group C and D atmospheres encompass?

Correct AnswerverifiedGroup C contains flammable gas or flamma...View AnswerShow Answer

What conditions are required for flexible cords and attachment plugs to be used in hazardous areas?

Correct AnswerverifiedWhen they are used, they must comply wit...View AnswerShow Answer

Intrinsically safe equipment and circuits operate________ .

Correct AnswerverifiedShow Answer

If a stem is longer than________in., lateral braces must be placed within 12 in. (300 mm) of the luminaire, or an explosionproof flexible coupling must be used within 12 in. (300 mm) of the junction box.

Correct AnswerverifiedShow Answer

The________ rating indicates the maximum operating temperature of a luminaire.

Correct AnswerverifiedShow Answer

Class III locations are areas that contain combustible________ .

Correct AnswerverifiedShow Answer

In general, the floor area of a garage, up to a level of 18 in. (450 mm) above the floor, is considered to be a________ location.

Correct AnswerverifiedShow Answer

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Great care must be exercised when instal...
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Hazardous locations are divided into two...
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D

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A

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NEC 513.1 defines an aircraft hangar as ...
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Group C contains flammable gas or flamma...
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When they are used, they must comply wit...
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