Lab Safety and Electrical Hazards Quiz

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).