Workplace Flashcards
When does an arc fault occur?
When the air gap ionizes and becomes conductive
When do Arc flashes commonly occur
Well workers are working on the equipment.
Which is riskier: removing a door that is hinged or door that is bolted?
Bolted
What elements in the operating environment can negatively impact the electrical equipments integrity?
Condensation, material failure, corrosion, dust
What are the specific potential effects of exposure resulting from arc flash?
20000 °C Burns Shrapnel Arc blast pressures (100's of lbs/ft²) Noise (165dB) Infrared and ultraviolet radiation Toxic vapours
What are three factors that determine the severity of an injury due to arc flash?
Working distance
Amount of heat
Time it takes the circuit breaker or fuse to open
What are the two primary hazards involved in working on energized electrical equipment?
Electric shock and arc flash
What is the distribution of fatalities between electrical shock and arc flash incidents?
1% due to arc flash, 99% due to electrocution
Who responsible for identifying hazards in the workplace and implementing preventative and protective control measures?
Occupational health and safety act and regulations
Which legal obligations does the Alberta OH&S specify for employers and employees?
2) Hazard assessment elimination and controls
15) Manage and control of hazardous energy (lockout tag out)
18) Personal protective equipment
What should be worn underneath Arc rated clothing, if anything?
100% natural fibre
Which document specifies when an energized electrical work permit may be required?
CSA Z462 workplace electrical safety standard
Which document describes how to identify an arc flash boundary?
CSA Z462 workplace electrical safety standard
What is the risk assessment procedure as outlined by the CSA Z462 used to determine?
Risk level Arc flash boundary distance Ark rated protective clothing required Limited and restricted approach boundaries Required shock related PPE Safe work practices
What is the Canadian standard that addresses electrical safety requirements for workers?
CSA Z462 workplace electrical safety standard
What are the three main Clauses of the CSA Z462 workplace electrical safety standard?
4) safety-related work practices
5) safety-related maintenance requirements
6) safety-related requirements for special equipment
Who is responsible to implement and document and electrical safety program?
Employers
What are two primary conditions regarding energized electrical conductors that are addressed in the CSA Z462?
1) electrical equipment conductors must be D energized unless energized work can be justified
2) only qualified persons may work on energized equipment
At what voltage level does energize work need to be justified?
50 volts
What are the three sections of the energized electrical work permit (EEWP)?
1) work to be done
2) shock assessment
3) signatures
What is a limited approach boundary?
Shock hazard exists
No shock related PPE required
Can be crossed only by a qualified person or an unqualified person escorted by a qualified person
What is a restricted approach boundary?
Inadvertent-movement-risk of shock exists
Use of shock PPE required
Qualified person only
Assumption that a qualified person may make contact with energized conductors and circuit parts with approved tools and equipment
What is the arc flash boundary?
Distance at which a person may be exposed to an incident energy of 1.2 calories/cm²
Is a worker who is standing at the arc flash boundary required to be wearing any arc related clothing?
No
What are the two methods used for completing the arc flash risk assessment?
1 arc flash incident energy calculations using formulas
2 arc flash Hazard identification/PPE category table method
What special labels would you expect to find on Arc rated clothing?
Arc thermal performance value (ATPV) or an energy break open threshold (EBT)
What do you have to determine before starting an arc flash risk assessment, using method 2?
1 Max short circuit current
2 Assumed max fault clearing time of upstream protective device.
What is bolted fault current?
Another word for the calculated short circuit current value
When using method 2: arc flash ppe category tables, how do you determine arc flash ppe category number?
Using:
Available short circuit current
Arc fault current
Arc duration
To find appropriate value in CSA Z462 Table 4B or 4C
Define working distance
Distance from potential arcing fault Source inside the equipment to the workers face and torso
What is the typical working distance for high voltage switchgear
910mm or 36”
What is the typical working distance for low voltage switchgear
610mm (24”)
What is the typical working distance for low voltage motor control centre and panel boards?
455mm (18”)
What are the two grounding classes?
Ungrounded and solidly grounded
Who’s responsible to ensure that workers have adequate understanding and training on the care use and maintenance of PPE
Employers
What’s the probability of protection of a worker from second-degree burns well using Arc rated clothing?
50%
What’s the difference between class 1a and class 1B spectacles?
1 A is for impact protection with side protection
1 B’s for impact and radiation protection with side protection
What are the three subclasses of goggles?
2A for impact protection
2B for impact dust and splash protection
2C are 2A or 2B with added radiation protection
What is incident energy exposure?
The amount of thermal energy the workers face and chest could be exposed to at the stipulated working distances
How is incident energy measured?
J/cm² or
Cal/cm²
How does weight affect arc flash protection level of clothing?
Higher weights provide more thermal insulation
g/m²) or (oz/yd²
How do layers affect arc flash protection level of clothing?
Multiple layers retain air space between layers providing greater thermal insulation
What groups are responsible for making sure apprentices are trained?
Journeyman and supervisors
Employers
Apprentices
What are the responsibilities of journeyman and supervisors?
1 acquire coaching skills
2 coach and mentor
3 supervise apprentices
4 make entries into record book as skills are acquired
What are the responsibilities of employers?
1 Provide on-the-job training for the apprentices
2 ensure the apprentice is supervised.
3 ensure the apprentices direct supervising journeyman makes the appropriate entries in the apprentices record book
What are the responsibilities of the apprentices?
1 Complete on the job training
2 Complete the number of apprenticeship training periods required under the contract
3 keep their record book up to date
What is the objective of the first step of coaching (tell)?
For the journeyman supervisor and The Apprentice to understand the intended outcome of the session
Describe the tell stage of a simplified coaching method
1 Explain a series of steps sequentially
2 Link learning to skills the learner already has
3 discuss benefits of the skill
4 talk safety concerns
How does the tell step Aid learning?
- Generate interest through interactive assessment
- Describes benefits of the skill
- Describes what, where, why, and how a task is accomplished
Describe the show step
Use same tools Explain as you go Go slow If skill is complex consider repeating demo Ask apprentice if they are ready to try
What is an essential part of the “do” step?
Close supervision, step-by-step guidance.
When is the first cycle of a simplified coaching method complete?
After The Apprentice finishes a task and the journeyman provides feedback
What is the difference between positive and constructive feedback?
Positive focuses on results and describes what’s good
Constructive focuses on results and corrects a problem
What is the plan stage of a simplified coaching lesson?
Defining the objective (including action word)
What is the industry Network composed of?
Alberta apprenticeship and Industry training board
Local apprenticeship committees
Provincial apprenticeship committees
Occupational committees
How much of an apprentices training takes place on the job?
80%
How many designated trades and occupations are in Alberta
Over 50
What are the responsibilities of the industry (employers and employees)?
Training and certification standards
Provide direction to the system through the industry committee Network and the alberta apprenticeship and Industry training board
What is the responsibility of the Alberta Government in the industry training system?
Why legislative framework and administrative support
What is the responsibilities of the technical Institutes?
Provide formal classroom training
What are the responsibilities of individual employers?
Employee trained and provide apprentices and opportunity to develop their skills
How many members are on the Alberta apprenticeship and Industry training board?
A chair and 12 members
