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4th Year Electrical - Machines > Arc Flash And Electrical Safety > Flashcards

Flashcards in Arc Flash And Electrical Safety Deck (32)
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1

What are six (6) effects that workers may experience when exposed to an arc-flash?

- temps as high as 20000*C resulting in severe burns and fire
- flying objects (molten metal/shrapnel)
- blast pressures up to 9700 kg/m2
- noise from blast up too 165 dB
- IR and UV radiation
- toxic vapours

2

What three (3) factors determine the severity of an injury due to arc flash?

- proximity to arching fault
- incident energy (heat)
- time for circuit to open

3

Two information resources for employers to reduce injuries due to arc flash

CSA Z462

Alberta OH&S

4

Two shock approach boundaries

- limited approach
- restricted approach

5

Eight (8) key elements of CSA Z462

- training
- developing
- working exposed to hazards
- safe work conditions
- justification for live work
- approach boundaries
- arc flash hazard analysis
- personal and other protective equipment

6

Minimum rating in cal/cm clothing when Arc flash PPE category is 1?

4 cal/cm2

7

Minimum rating in cal/cm clothing when Arc flash PPE category is 2?

8 cal/cm2

8

Minimum rating in cal/cm clothing when Arc flash PPE category is 3?

25 cal/cm2

9

Minimum rating in cal/cm clothing when Arc flash PPE category is 4?

40 cal/cm2

10

What class are goggles as per CSA standards?

2

11

What CSA standard must all safety glasses meet?

CSA Z94

12

What are the three (3) characteristics of clothing that the CSA Z462 considers when selecting them for PPE?

- resists catching on fire
- self-extinguishing
- provides thermal insulation from heat radiation

13

What does the acronym ATPV stand for?

Arc Thermal Performance Value

14

Six (6) lockout steps

- warn personnel
- proper shutdown procedures
- disconnect from supply
- lock and tag
- test before touch
- reenergize

15

What is the purpose of a safety lockout hasp?

Allows more than one padlock to be used

16

How many keys per padlock?

1

17

What CSA class are spectacles with impact and radiation?

1B

18

PPE that protects from flames has what type of fabric characteristics?

- resists flames
- self-extinguishing
- thermally insulated

19

Canadian standard that addresses electrical safety requirements for employees

CSA Z462

20

Heat from arc flash can reach temps up too

20 000 C

21

Persons who cross restricted approach boundary must be qualified.

True or False?

True

22

Three things arc flash victims can experience

- severe burns
- embedded blast shrapnel
- temporary blindness

23

Before working on any equipment that has just been deenergized you must

Test before touch

24

Three documents an employer can reference to reduce injuries created by arc flashes

CZA Z462
NFPA 70E
OH&S Act

25

Who sets criteria for training qualified persons to perform a hazard/risk analysis

CSA Z462

26

CSA Z462 Risk assessment procedures are used to determine

- risk level (low, med, high)
- arc flash risk assessment
- shock risk assessment
- safe work practices

27

Arc flash boundary is

Distance from arc fault a person may be exposed to an incident energy of 1.2 cal/cm2

28

What is arc fault current measures in?

Kilo-amperes

29

Typical working distance of high voltage switchgear

36" (910mm)

30

Typical working distance of low voltage switchgear

24" (610 mm)