e) Arc Flash And Electrical Safety Flashcards
What are some potential hazards of arc flash exposure?
- Temperatures up to 20,000°C
- Extreme arc blast pressures
- Hot molten shrapnel
- Noise levels up to 165 dB
- Intense infrared and ultraviolet radiation
- Toxic vapours
Three factors that determine the potential severity of injury or damage due to arc flash:
- Working distance from the arcing fault
- The amount of abnormal arcing fault that occurs
- Time it takes for the over current to open the circuit
At what current does an individual lose the ability their ability to release their hand grip?
10mA - Paralysis threshold of arms and hands
What effect does 30mA have on the human body?
Respiratory paralysis - breathing may stop
At what current level are the effects imperceptible?
< 1mA
True or False:
OHS requires any worker potentially exposed to arc flash to wear nylon or polyester underneath the arc-rated clothing.
False - clothing worn under the arc-rated PPE should be 100% natural fibre (ex: cotton)
In order from safest to least safe list the 6 risk control methods hierarchy
- Elimination
2.Substitution
3.Engineering
4.Awareness
5.Administrative controls - PPE
What are the two information resources available to help reduce injuries due to arc-flash and shock?
CSA Z462 Workplace electrical safety
Alberta OHS Act
How many sections is an EEWP divided into
Three
The killing factor of electrical shock is what?
Current
What is the arc flash boundary?
The distance from an arcing fault at which a person may be exposed to an incident energy of 1.2 calories/cm2
True or False:
An unqualified person is permitted to cross a limited approach boundary if they are escorted by a qualified person
True
True or False:
An unqualified person is permitted to cross a limited approach boundary if they are escorted by a qualified person
True
