Arc Flash And Electrical Safety Flashcards
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
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
Two information resources for employers to reduce injuries due to arc flash
CSA Z462
Alberta OH&S
Two shock approach boundaries
- limited approach
- restricted approach
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
Minimum rating in cal/cm clothing when Arc flash PPE category is 1?
4 cal/cm2
Minimum rating in cal/cm clothing when Arc flash PPE category is 2?
8 cal/cm2
Minimum rating in cal/cm clothing when Arc flash PPE category is 3?
25 cal/cm2
Minimum rating in cal/cm clothing when Arc flash PPE category is 4?
40 cal/cm2
What class are goggles as per CSA standards?
2
What CSA standard must all safety glasses meet?
CSA Z94
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
What does the acronym ATPV stand for?
Arc Thermal Performance Value
Six (6) lockout steps
- warn personnel
- proper shutdown procedures
- disconnect from supply
- lock and tag
- test before touch
- reenergize
What is the purpose of a safety lockout hasp?
Allows more than one padlock to be used
How many keys per padlock?
1
What CSA class are spectacles with impact and radiation?
1B
PPE that protects from flames has what type of fabric characteristics?
- resists flames
- self-extinguishing
- thermally insulated
Canadian standard that addresses electrical safety requirements for employees
CSA Z462
Heat from arc flash can reach temps up too
20 000 C
Persons who cross restricted approach boundary must be qualified.
True or False?
True
Three things arc flash victims can experience
- severe burns
- embedded blast shrapnel
- temporary blindness
Before working on any equipment that has just been deenergized you must
Test before touch
Three documents an employer can reference to reduce injuries created by arc flashes
CZA Z462
NFPA 70E
OH&S Act
Who sets criteria for training qualified persons to perform a hazard/risk analysis
CSA Z462
CSA Z462 Risk assessment procedures are used to determine
- risk level (low, med, high)
- arc flash risk assessment
- shock risk assessment
- safe work practices
Arc flash boundary is
Distance from arc fault a person may be exposed to an incident energy of 1.2 cal/cm2
What is arc fault current measures in?
Kilo-amperes
Typical working distance of high voltage switchgear
36” (910mm)
Typical working distance of low voltage switchgear
24” (610 mm)
Typical working distance of low-voltage MCC and panelboards
18” (455 mm)
Three (3) factors to consider when determining proper arc flash PPE
- material selection
- thermal insulation
- layers of protection
