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Chapter 1 of 12 • Page 1 of 248🔒 Protected PDF • Watermarked
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ElectricalBasic Electrical
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Do not use appliances, if

A

damaged

B

wires exposed

C

working properly

D

both a and b

Correct Answer

Concept & PrincipleElectricalBasic Electrical
Option D

both a and b

Quick Summary: Operating an electrical appliance that is physically damaged or has exposed wiring poses a severe risk of electric shock and fire hazards. Insulation failure or structural compromise disrupts the safety path of the current, making it unsafe for human interaction.

💡 Explanation

Operating an electrical appliance that is physically damaged or has exposed wiring poses a severe risk of electric shock and fire hazards. Insulation failure or structural compromise disrupts the safety path of the current, making it unsafe for human interaction.

🔢 Key Formulas

I=VRI = \frac{V}{R}I=RV​ — Ohm's Law governing fault current magnitude

P=I2RP = I^2 RP=I2R — Power dissipation leading to heat and fire risk

⚙️ Working Principle

Electrical safety relies on the integrity of insulation to prevent current from leaking to the chassis or the user. When a device is damaged or wires are exposed, the 'Live' conductor may come into contact with the device's outer casing or a person's skin. Since human body resistance is relatively low compared to the path of a short circuit, an unintended current path forms, potentially leading to fatal macroshock or accidental arcing.

📌 Key Points
  • ▸

    Damaged casing risks mechanical injury and potential contact with energized parts.

  • ▸

    Exposed wires bypass primary safety insulation, creating immediate shock hazards.

  • ▸

    Always perform a visual inspection of power cords and plugs before usage.

  • ▸

    Never attempt to repair mains-operated appliances with improvised insulation like tape.

✅ Advantages
  • ▸

    Prevents accidental electrocution

  • ▸

    Reduces the risk of localized electrical fires

🛠️ Applications / Uses
  • ▸

    Domestic appliance safety

  • ▸

    Industrial machinery maintenance protocols

📄 Additional Information
  • ▸

    Exposed copper wires indicate that the dielectric strength of the insulation has been completely compromised.

  • ▸

    Option C is incorrect because a device working properly is safe to use unless other external hazards are present.

  • ▸

    The combination of A and B covers both internal failure (casing) and external supply path failure (wiring).

📊 Diagram / Illustration
Safety Warning: Hazard DetectionRisk: Current Leakage (Iₗₑₐₖ)
Ifault=VZbody+ZinsulationI_{fault} = \frac{V}{Z_{body} + Z_{insulation}}Ifault​=Zbody​+Zinsulation​V​
Condition: Insulation Failure at Point of Exposure
✅

D is correct — Using appliances with physical damage or exposed wires creates a direct path for current to pass through the user or surroundings, leading to shock or fire.

Core Concepts Used
Click any tag to open in AI Tutor
Electrical Safety Insulation Integrity Fault Current Hazards
💡 EXAM TIP

In competitive exams, always prioritize the most comprehensive answer; since both A and B are hazardous, 'both a and b' is the logically correct choice.

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