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Questions and Answers
What is the primary hazard when working in an electrical lab?
What is the primary hazard when working in an electrical lab?
Which safety precaution should be taken before handling electrical wiring?
Which safety precaution should be taken before handling electrical wiring?
What should you do if you encounter an electrical fire?
What should you do if you encounter an electrical fire?
What is recommended regarding extension cords in the lab?
What is recommended regarding extension cords in the lab?
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Why should loose clothing be avoided around machinery?
Why should loose clothing be avoided around machinery?
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Which of the following is NOT recommended for protection against excessive current?
Which of the following is NOT recommended for protection against excessive current?
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When working with capacitors, what is a key assumption you should make?
When working with capacitors, what is a key assumption you should make?
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What is considered a safe practice regarding the use of electrical instruments?
What is considered a safe practice regarding the use of electrical instruments?
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What is the maximum harmless current intensity that can be tolerated by the human body without pain?
What is the maximum harmless current intensity that can be tolerated by the human body without pain?
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Which range of current intensity is associated with painful shock and loss of muscular control?
Which range of current intensity is associated with painful shock and loss of muscular control?
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What is one of the severe consequences of a current intensity over 2000 mA?
What is one of the severe consequences of a current intensity over 2000 mA?
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How does the duration of exposure to electrical shock affect the severity of injury?
How does the duration of exposure to electrical shock affect the severity of injury?
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What does a current reading of 100 mA – 2000 mA indicate?
What does a current reading of 100 mA – 2000 mA indicate?
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What is the first step in providing first aid for an electric shock victim?
What is the first step in providing first aid for an electric shock victim?
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What effect does high voltage have on current flow through a victim's body?
What effect does high voltage have on current flow through a victim's body?
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Which of the following statements about low voltage shocks is correct?
Which of the following statements about low voltage shocks is correct?
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What is the primary purpose of the green wire in a 3-wire system?
What is the primary purpose of the green wire in a 3-wire system?
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Why is grounding electrical equipment crucial?
Why is grounding electrical equipment crucial?
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What factor does NOT contribute to insulation failure?
What factor does NOT contribute to insulation failure?
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Which device is used to determine if a circuit is properly grounded?
Which device is used to determine if a circuit is properly grounded?
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In a high voltage environment, what is important regarding the grounding of the operator?
In a high voltage environment, what is important regarding the grounding of the operator?
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What could potentially cause holes in insulation?
What could potentially cause holes in insulation?
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Which overcurrent protection device is more prone to failure without warning?
Which overcurrent protection device is more prone to failure without warning?
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What type of tester is used for general voltage checks between 110 to 220 V?
What type of tester is used for general voltage checks between 110 to 220 V?
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Which electrical hazard is associated with the presence of water?
Which electrical hazard is associated with the presence of water?
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What percentage of electrocution cases in Ontario between 2006 and 2015 involved public places?
What percentage of electrocution cases in Ontario between 2006 and 2015 involved public places?
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What is the primary purpose of grounding in electrical systems?
What is the primary purpose of grounding in electrical systems?
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In DC electrical systems, which side is typically grounded?
In DC electrical systems, which side is typically grounded?
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What is the consequence of using a metal ladder while working on electrical equipment?
What is the consequence of using a metal ladder while working on electrical equipment?
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Which of the following is NOT a source of electrical hazards?
Which of the following is NOT a source of electrical hazards?
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What type of grounding is used in AC electrical systems?
What type of grounding is used in AC electrical systems?
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How does electrocution compare to electrical burn injuries in terms of lost time injury claims?
How does electrocution compare to electrical burn injuries in terms of lost time injury claims?
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What should be done if an extension cord feels hot?
What should be done if an extension cord feels hot?
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Which of the following is an essential requirement in SEMET labs regarding footwear?
Which of the following is an essential requirement in SEMET labs regarding footwear?
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What is the required action regarding laboratory equipment in SEMET labs?
What is the required action regarding laboratory equipment in SEMET labs?
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What sensation does the threshold of perception for electric current typically cause?
What sensation does the threshold of perception for electric current typically cause?
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What is the consequence of vandalism in SEMET labs?
What is the consequence of vandalism in SEMET labs?
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How often should students inspect their equipment in SEMET labs?
How often should students inspect their equipment in SEMET labs?
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When is wearing safety glasses mandatory in SEMET labs?
When is wearing safety glasses mandatory in SEMET labs?
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What is the location of safety equipment in SEMET labs?
What is the location of safety equipment in SEMET labs?
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Study Notes
Lab Safety and Electrical Hazards
- Electrical work poses significant risks, including electric shock and burns.
- Always prioritize safety; never work alone. Use CSA-approved tools and three-wire/double-insulated equipment.
- Power should always be shut off before handling wiring. Inspect cords for damage. Wear appropriate footwear.
- Avoid working with wet skin, leaving hot soldering irons unattended, or wearing loose clothing near machinery. Ensure adequate lighting. Assume all capacitors are charged and regularly inspect insulation.
- Always verify circuit voltages before working. Never use water on electrical fires. Use fuses and circuit breakers for overcurrent protection.
Electric Cords and SEMET Lab Safety
- Improper cord use accounts for 2500 workplace injuries annually. Avoid extended extension cord use, covering cords with rugs, and simply unplugging hot cords.
- SEMET labs require a professional and safe work environment. Know fire extinguisher and safety station locations. Food and drink are prohibited.
- Safety glasses, appropriate clothing (no open-toed shoes, long hair tied back), and ESD wristbands (where applicable) are mandatory.
- All equipment must be CSA-approved and in good working order. Vandalism is strictly prohibited and subject to disciplinary action. Non-compliance results in a zero grade.
- Safety glasses are mandatory when power is ON in specific SEMET labs (K2200, A4056, A4058, A4060, A4066, A4068, A4070, A4071, A4072, A4073). Each lab has a safety station, telephone, and issue sheet.
Electrical Shock and its Effects
- Electric shock results from electric current passing through the body. Severity depends on factors like age, gender, and physical condition.
- The perception threshold is about 1 mA (tingling/heating). 5 mA is considered the maximum harmless current.
- Higher currents (6-16 mA) cause pain and loss of muscle control. 17-99 mA can lead to extreme pain, breathing difficulties, and potential death.
- Currents above 100 mA can cause ventricular fibrillation and death. >2000 mA leads to cardiac arrest, severe burns, and probable death.
- Low voltage can also be fatal. Injury severity depends on current magnitude and duration of exposure. Even 49V can cause fatalities.
High Voltage, First Aid, and Electrical Hazard Sources
- Higher voltages lead to proportionally higher currents and more severe injuries (e.g., high voltage can produce currents as high as 4 amps resulting in organ damage, burns, and limb severance).
- First aid: Shut off power; carefully separate victim from source (without touching them directly); call emergency services.
- Common electrical hazard sources include bare wires, unlabeled equipment, improper grounding, damp environments, metal ladders used near electrical equipment, failure to shut off power, and lightning strikes.
Electrocution Statistics, Grounding and 3-Wire Systems
- Electrocution accounts for about 20% of construction fatalities in Canada. In Ontario (2006-2015), 94 deaths resulted from electrical fires and 63 from electrocution. A significant number were occupational accidents within electrical trades.
- Grounding provides a low-impedance path to earth, protecting equipment and users from voltage spikes (AC systems). In DC systems, ground is usually the negative terminal.
- A standard 3-wire wall plug has a live wire (carrying current to the load), a neutral wire (returning current), and a ground wire (low-resistance path for rogue voltages).
Grounding, Overcurrent Protection, and Insulation Failure
- Grounding protects against electrical shock by isolating equipment enclosures from live wires. Proper grounding is crucial, especially in high-voltage settings.
- Overcurrent protection devices (fuses and circuit breakers) prevent excessive current flow that could cause fires or damage.
- Insulation failure can occur due to sunlight exposure, sparks, high temperatures, animal damage, abrasion, and moisture.
Detecting Electrical Hazards
- Electrical hazards can be detected using tools such as circuit testers (for voltage), receptacle testers (for outlet wiring integrity), and continuity testers (for ground connection and circuit breaks).
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Description
Test your knowledge on lab safety and electrical hazards. This quiz covers essential safety practices, risks associated with electrical work, and proper use of electrical equipment and cords. Ensure you understand the importance of safety in laboratory environments.
