ITI Electrician Safety MCQ – Electrician Safety Objective Question & Answer

In the event of a fire, especially an electrical fire, it’s crucial to turn off fans and air circulators. This is because:

• Fans can spread the fire: Air movement can provide more oxygen to the fire, making it burn faster and spread more quickly.
• Fans can spread smoke and fumes: Fans can circulate smoke and toxic fumes throughout the building, making it harder for people to escape and increasing the risk of smoke inhalation.

• The incorrect statement is Touch bare conductors during troubleshooting.
• It is extremely dangerous to touch bare conductors (wires) during troubleshooting or any other time unless you are absolutely certain the circuit is de-energized and properly locked out/tagged out.
• Touching bare conductors is extremely dangerous and can lead to electric shock or electrocution. Always ensure that power is turned off and use appropriate tools and safety measures when troubleshooting.

The factors that are helpful in determining the intensity of electric shock include:

1. Body Resistance: The resistance of the human body can vary based on factors such as moisture, skin condition, and contact area. Lower resistance allows more current to flow through the body, increasing the intensity of the shock.
2. Magnitude of Current: The amount of current that flows through the body is a critical factor in the severity of the shock. Higher currents can cause more severe injuries and increase the risk of fatal outcomes.
3. Contact Time: The duration for which a person is in contact with the electrical source also plays a significant role. Longer contact times can lead to greater tissue damage and higher chances of fatality.

Insulating gloves designed for electrical work are primarily made up of Rubber.

• Material Properties: Rubber is used because it has high dielectric properties, which means it effectively resists the flow of electrical current. This makes rubber gloves suitable for protecting against electrical shocks when working near live wires or electrical equipment.
• Types of Insulating Gloves: Insulating gloves are classified based on their voltage ratings, with rubber being the standard material used across various classes (e.g., Class 00 to Class 4), indicating their effectiveness at different voltage levels.
• Additional Features: These gloves are designed to provide comfort and dexterity while ensuring safety from electrical hazards.

• In electric circuits, the personal protective ground’s function is to provide low impedance path for short circuit current.
• Personal protective grounds (PPGs), also known as grounding or earthing leads, are used to create a low-resistance path to ground.
• This is crucial for safety in electrical work. If a live conductor is accidentally contacted, the short-circuit current will take the path of least resistance to ground.
• A properly installed PPG provides this low-resistance path, allowing a large current to flow quickly to ground, tripping protective devices like circuit breakers or fuses and minimizing the risk of electric shock to personnel.
•  A low impedance path ensures that the fault current can dissipate quickly and effectively, minimizing the risk of electric shock to personnel working on or near the equipment.

When a person touches an electrically live part of an appliance, A step potential occurs when a person walks on an electrically conducting and live surface potential between two feet.

Step potential, also known as step voltage, is a hazardous electrical phenomenon that occurs when a person stands near an energized grounded object, particularly during electrical faults like downed power lines or faulty grounding systems. It refers to the voltage difference between a person’s feet, which can cause a dangerous current to flow through their body.

• Definition: Step potential is the voltage difference between two points on the ground, typically separated by a distance roughly equal to a human stride (approximately 1 meter or 3 feet). When a fault current enters the ground, it spreads out, creating a voltage gradient.
• Voltage Gradient: When a fault occurs, such as a downed power line, the fault current spreads through the ground, creating a voltage gradient. This means that the voltage is highest near the fault and decreases as you move away from it.
• Step Potential: The difference in voltage between two points (typically the feet of a person) can result in dangerous currents flowing through the body if a person stands on ground with varying potentials.
• Safety Implications: Understanding this gradient is crucial for safety, as it highlights the risks associated with approaching energized equipment or areas affected by electrical faults.

When the neutral wire of the phase is shorted, the most likely effect is the High current will flow and fire.

• Normal Circuit Operation: In a normal AC circuit, the current flows from the live (phase) wire through the load (appliance) and returns through the neutral wire. The neutral wire provides a return path for the current.

• Short Circuit: When the neutral wire is shorted (meaning it comes into direct contact with the live/phase wire), it creates a path of very low resistance. This allows a very large current to flow. This is because the load (appliance) is bypassed, and the only resistance is the very small resistance of the wires themselves.

• High Current Flow: The low resistance path results in a significant increase in current, often far exceeding the normal operating levels. This can lead to overheating of wires and components.
• Fire Risk: The excessive current can generate heat, which poses a serious risk of fire. If the circuit protection devices (like fuses or circuit breakers) fail to operate correctly or are not present, this high current can cause insulation to melt and potentially ignite surrounding materials.

Machinery without protection can be classified as Mechanical hazard.

• Mechanical Hazard: This term refers to dangers associated with machinery that can cause physical harm due to moving parts, sharp edges, or other mechanical components. When machinery lacks proper safeguards, it poses significant risks of injury to operators and nearby personnel.

Aggressive behavior of an employee can be classified as Psychological danger.

• Psychological Danger: This classification pertains to behaviors that threaten the mental and emotional well-being of individuals in the workplace. Aggressive behavior can manifest in various forms, such as verbal abuse, intimidation, bullying, and harassment, which can create a hostile work environment and lead to psychological stress for affected employees.

The rough value for the internal resistance of the human body is 300-1000Ω.

Internal Resistance: The internal resistance of the human body is approximately 300Ω under normal conditions. The internal resistance is primarily due to tissues and fluids within the body, is significantly lower. Research and various sources suggest a range of 300-1000 Ω as a reasonable approximation.

External Resistance: The skin, particularly dry skin, offers the highest resistance (can be over 100,000 Ω). While wet skin can reduce this resistance to around 1000Ω or lower.