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LVL 4 ELEC > D7 > Flashcards

D7 Flashcards

1
Q

What is a key consideration in the development of the CEC?

A

The prevention of fire.

LT1 PG8

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2
Q

A hazardous location is an area in which…

A

Either explosive gas or dust atmospheres exist or may exist

LT1 PG8

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3
Q

To achieve a reduced ignition risk what two fundamental things are necessary?

A

1) hazardous locations are correctly identified and classified.
2) designers and installers abuse by the rigorous requirements for electrical installations.

LT1 PG8

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4
Q

Who is a qualified person that can carry out and document the classification of a hazardous location?

A

Professional engineers.

LT1 PG8

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5
Q

For small areas, the classification may be performed by?

A

A single discipline of engineer.

LT1 PG8

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6
Q

For large facilities the classification of hazardous locations would be done by?

A

Multiple disciplines of engineer, collaboratively.
Process engineers, heating and ventilation engineers, electrical engineers, and so on.

LT1 PG8

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7
Q

What section of the CEC is standards of the zone classification system found in?

A

Section 18

LT1 PG9

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8
Q

What are zones 0, 1, and 2 used to classify?

A

Explosive gas atmospheres.

LT1 PG9

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9
Q

What are zones 20, 21, and 22 used to classify?

A

Explosive dust atmospheres

LT1 PG9

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10
Q

Likelihood is based on what two factors?

A

Frequency explosive atmosphere would be present.

Amount of time explosive atmosphere would be present.

LT1 PG9

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11
Q

The likelihood of explosive atmospheres being present is captured in numerical order of the zones. Does the likelihood increase or decrease from zone 0 to zone 2?

A

Decrease.
The lower the number the higher the frequency/time of explosive atmosphere.

LT1 PG9

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12
Q

What is a “group”?

A

A sub-classification within a zone that distinguishes between different types of gases and dust.

LT1 PG9/10

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13
Q

What system was used to classify hazardous locations previous to the zone/group system?

A

Class/division system.

LT1 PG10

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14
Q

What is a hazardous location?

A
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15
Q

The class/division system of classification for hazardous locations is based on IEC standards.

A

False.
It is the zone system of classification that is based on IEC standards.

Self Test 1

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16
Q

In the zone system, each zone is further broken down into divisions.

A

False.
They are broken down in to groups.
Divisions are used in the class system.

Self Test 1

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17
Q

Facilities already using the class/division system may continue to use this system for additions.

A

True
The CEC includes provisions for this in 18-000 3)

Self Test 1

18
Q

Under the zone system of classification, acetylene would be categorised into group…

A

C - group IIC

Self Test 1

19
Q

Under the zone system of classification, the least hazardous gases are categorized under group…

A

A - Group IIA

20
Q

Natural gas is classified into group IIA in the zone system, provided that it contains no more than __% hydrogen.

A

25%

Self Test 1

21
Q

What does LFL stand for?

A

Lower flammable limit

Self Test 1

22
Q

What does UFL stand for?

A

Upper flammable limit

Self Test 1

23
Q

In the zone system, groups are arranged based on relative hazard in _____ alphabetical order. This means?

A

Ascending alphabetical order.

A is least hazardous
C is most hazardous

LT1 PG12

24
Q

In the class/division system, the groups are arranged based on relative hazard in ______ alphabetical order. This means?

A

Descending

For gas:
D is least hazardous
A is most hazardous

For dust:
G is least hazardous
E is most hazardous

LT1 PG12

25
Q

Zone 0

A

Gas
Present continuously or for long periods

LT1 PG9

26
Q

Zone 1

A

Gas
Likely to occur in normal operation / adjacent to zone 0 area

LT1 PG9

27
Q

Zone 2

A

Gas
Not likely to occur in normal operation, is for short period if it does / adjacent to zone 1

LT1 PG9

28
Q

Zone 20

A

Dust
Present continuously for long periods or frequently

LT1 PG9

29
Q

Zone 21

A

Dust
Likely to occur in normal operation

LT1 PG9

30
Q

Zone 22

A

Dust
Not likely to occur in normal operation, is for short periods if it does.

LT1 PG9

31
Q

What are the two most important factors to consider to ensure equipment installed within a hazardous location is safe?

A

1) whether the equipment could cause ignition either in normal operation or in the event of a failure.

2) whether the equipment enclosure has the ability to contain an explosion within the equipment without causing ignition of the explosive atmosphere

LT2 PG16

32
Q

Intrinsically safe electrical systems and non-incendive wiring circuits are similar in design and application. What 3 components do they generally consists of?

A

Field barrier device
Barrier device
Associated wiring

LT2 PG16

33
Q

Where is the field barrier device installed?

A

Within the hazardous location

LT2 PG16

34
Q

Where is the barrier device installed?

A

In the non-hazardous location.

LT2 PG16

35
Q

What does an “explosion proof” rating indicate?

A

That if installed correctly, the enclosure is capable of safely containing an explosion within in.

35
Q

What does an “explosion proof” rating indicate?

A

That if installed correctly, the enclosure is capable of safely containing an explosion within in.

LT2 PG17

36
Q

Which system (zone/group, class/division) is the term “explosion proof” applicable to?

A

It is only applicable to the class/division system
Is also most often associated with NEMA 7 ratings.

LT2 PG17/18

37
Q

Which system is the term “flameproof” applicable to?

A

It is applicable to the zone/group system.
It is the equivalent term to “explosion proof” from the class/division system.

LT2 PG18

38
Q

What does the temperature class of equipment relate to?

A

The maximum surface temperature that the enclosure or equipment will rise to.

LT2 PG19

39
Q

What are Equipment Protection Levels (EPL)?

A

EPL is a comprehensive rating system that overrides other factors and must be followed if present.

LT2 PG19

LVL 4 ELEC (8 decks)

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