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Maharashtra HSC Multi-Skill Electrical (NSQF) study materials
Maharashtra HSC Multi-Skill Electrical (NSQF) study resources

Maharashtra HSC Multi-Skill Electrical (NSQF) practice questions

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Question 1Basic Electrical Fundamentals and Safety

Which condition is required for an electric current to flow continuously in a closed circuit?

  1. A complete conducting path and a source of electromotive force Correct answer.
  2. An open switch and a charged capacitor
  3. A complete conducting path made only of copper
  4. A magnetic field crossing the conductor

Explanation

Current flows only when there is a closed loop of conducting material and some source of emf to maintain potential difference. Copper is a good conductor but any conductor works, so the material alone is not the requirement. An open switch breaks the path and stops the current.

Question 2Basic Electrical Fundamentals and Safety

A resistor of 220 Ω carries a current of 0.5 A. What is the potential difference across it?

  1. 110 V Correct answer.
  2. 440 V
  3. 220 V
  4. 55 V

Explanation

Ohm's law states V = I × R. Substituting I = 0.5 A and R = 220 Ω gives V = 110 V. The other values come from multiplying or dividing the given numbers incorrectly.

Question 3Basic Electrical Fundamentals and Safety

Which unit is used to express electrical resistance in the SI system?

  1. Ampere
  2. Volt
  3. Watt
  4. Ohm Correct answer.

Explanation

Resistance is measured in ohms, symbol Ω, defined as the resistance that allows one ampere to flow when one volt is applied. The volt measures potential difference, the ampere measures current, and the watt measures power.

Question 4Basic Electrical Fundamentals and Safety

Why is earthing of the metal body of an electrical appliance necessary?

  1. It provides a low-resistance path so fault current trips the protective device Correct answer.
  2. It increases the operating voltage of the appliance
  3. It converts alternating current into direct current
  4. It reduces the power consumption of the appliance

Explanation

Earthing connects exposed metal parts to the general mass of earth through a low-resistance conductor. If a live wire touches the body, fault current flows to earth and operates the fuse or MCB quickly, limiting the touch voltage. Earthing does not change voltage, power consumption, or the type of supply.

Question 5Basic Electrical Fundamentals and Safety

Two resistors of 6 Ω and 3 Ω are connected in parallel. What is the equivalent resistance?

  1. 9 Ω
  2. 4.5 Ω
  3. 18 Ω
  4. 2 Ω Correct answer.

Explanation

For two resistors in parallel, Rp = (R1 × R2)/(R1 + R2) = (6 × 3)/(6 + 3) = 18/9 = 2 Ω. The equivalent resistance of a parallel combination is always less than the smallest branch resistance.

Question 6Basic Electrical Fundamentals and Safety

Which material is used for the filament of an incandescent lamp because of its high melting point?

  1. Tungsten Correct answer.
  2. Aluminium
  3. Copper
  4. Nichrome

Explanation

Tungsten has a very high melting point (about 3400 °C) and retains strength at white-heat temperatures, so it can glow without melting. Copper and aluminium melt far earlier, and nichrome is used for heating elements where glowing is not required at such temperature.

Question 7Basic Electrical Fundamentals and Safety

What is the effect on the resistance of a conductor if its length is doubled while the cross-sectional area stays the same?

  1. The resistance remains unchanged
  2. The resistance becomes half
  3. The resistance becomes four times
  4. The resistance becomes double Correct answer.

Explanation

Resistance is directly proportional to length, R = ρL/A. Doubling L while keeping area and resistivity constant doubles the resistance. Halving would occur if the area were doubled instead.

Question 8Basic Electrical Fundamentals and Safety

A 1500 W geyser runs on a 230 V supply. What current does it draw?

  1. 15.0 A
  2. 3.45 A
  3. 6.52 A Correct answer.
  4. 0.153 A

Explanation

Power in a resistive load is P = V × I, so I = P/V = 1500/230 ≈ 6.52 A. The other values come from multiplying or from using the wrong formula.

Question 9Basic Electrical Fundamentals and Safety

Which protective device operates by melting an internal element when excess current flows?

  1. MCB
  2. Fuse Correct answer.
  3. Earth leakage relay
  4. ELCB

Explanation

A fuse contains a calibrated metal element that melts and opens the circuit when current exceeds its rating. An MCB trips by thermal or magnetic action and can be reset, while ELCB and earth leakage relays respond to leakage current to earth.

Question 10Basic Electrical Fundamentals and Safety

Why is a capacitor connected across the terminals of a small DC motor in an appliance?

  1. To suppress sparking and radio-frequency interference at the brushes Correct answer.
  2. To step up the supply voltage
  3. To increase the motor speed permanently
  4. To convert the motor into a generator

Explanation

Brush commutation produces small arcs that radiate radio-frequency noise. A capacitor across the terminals bypasses these high-frequency surges and reduces sparking. It does not change steady speed, raise voltage, or reverse the machine's function.

Question 11Basic Electrical Fundamentals and Safety

What is the function of a step-down transformer in a distribution system?

  1. It reduces alternating voltage while increasing current capacity Correct answer.
  2. It converts alternating current into direct current
  3. It reduces voltage and reduces current in the same ratio
  4. It changes the frequency of the supply

Explanation

A transformer transfers energy by mutual induction, so the secondary voltage falls in proportion to the turns ratio while the current rises inversely, neglecting losses. It does not rectify, and it cannot change frequency.

Question 12Basic Electrical Fundamentals and Safety

A worker must switch off a circuit for maintenance. Which practice best ensures safety?

  1. Isolating the supply, locking the isolator, and proving the circuit dead Correct answer.
  2. Switching off the load switch and starting work at once
  3. Wearing rubber footwear and working on the live circuit
  4. Asking a colleague to watch the switch during the work

Explanation

Safe isolation means opening the supply, locking or tagging the isolator to prevent reconnection, and testing with an approved voltage detector to prove the conductors are dead. Simply switching off or relying on another person leaves the circuit open to accidental re-energisation.

Question 13Basic Electrical Fundamentals and Safety

In a three-pin plug, which conductor is connected to the longest pin?

  1. Any of the three
  2. Neutral
  3. Live
  4. Earth Correct answer.

Explanation

The earth pin is made longer and thicker so that it makes contact first on insertion and breaks last on withdrawal, ensuring the appliance body is earthed before the live connection is made. Live and neutral pins are shorter.

Question 14Basic Electrical Fundamentals and Safety

Two resistors of 4 Ω and 8 Ω are connected in series across a 12 V supply. What is the voltage across the 8 Ω resistor?

  1. 12 V
  2. 8 V Correct answer.
  3. 4 V
  4. 6 V

Explanation

The total resistance is 12 Ω, so the current is 12/12 = 1 A. The voltage across the 8 Ω resistor is then I × R = 1 × 8 = 8 V. In a series circuit the larger resistance drops the larger share of the supply voltage.

Question 15Basic Electrical Fundamentals and Safety

What happens to the total resistance when more resistors are added in parallel to a circuit?

  1. It increases in proportion to the number added
  2. It decreases and is always less than the smallest branch resistance Correct answer.
  3. It becomes equal to the sum of all branch resistances
  4. It stays the same because the supply voltage is fixed

Explanation

Each parallel branch provides an additional path for current, so the total current rises for the same voltage and the equivalent resistance falls. The equivalent is always smaller than the least branch resistance.

Question 16Basic Electrical Fundamentals and Safety

A fuse rated 5 A protects a circuit. Which situation will cause it to blow?

  1. A supply voltage of 250 V with a 2 A load
  2. A current of 3 A flowing steadily
  3. A momentary switch-on surge of 6 A lasting a few milliseconds
  4. A current of 8 A flowing for a sustained period Correct answer.

Explanation

A fuse element is calibrated to melt when current exceeds its rating for a sufficient time. A sustained 8 A overload heats the element beyond its melting point. Normal loads and very brief surges below the fusing energy do not melt the element.

Question 17Basic Electrical Fundamentals and Safety

Which statement correctly describes the relationship between electrical energy and power?

  1. Power is energy multiplied by time
  2. Power and energy are the same quantity in different units
  3. Energy is power multiplied by time of use Correct answer.
  4. Energy is power divided by the supply voltage

Explanation

Power is the rate of doing work or transferring energy, so energy transferred equals power multiplied by time, E = P × t. The kilowatt-hour used in billing is exactly this product. Power and energy are distinct quantities.

Question 18Basic Electrical Fundamentals and Safety

An electric iron rated 1000 W at 230 V is used for 3 hours daily. What energy does it consume in 30 days?

  1. 30 kWh
  2. 90 kWh Correct answer.
  3. 300 kWh
  4. 9 kWh

Explanation

Daily energy is 1 kW × 3 h = 3 kWh, and over 30 days that is 3 × 30 = 90 kWh. Multiplying power in watts without converting to kilowatts gives a result a thousand times too large.

Question 19Basic Electrical Fundamentals and Safety

Which action is the correct first response if a person is found in contact with a live conductor?

  1. Wait for the person to release the conductor
  2. Throw water on the conductor to cool it
  3. Switch off the supply or isolate it before touching the person Correct answer.
  4. Pull the person away by the arm immediately

Explanation

The rescuer must break the supply first, using the main switch or another safe means, because touching a person still in contact with a live conductor can pass current through the rescuer as well. Only after isolation should first aid be given.

Question 20Basic Electrical Fundamentals and Safety

Why is the neutral conductor normally connected to earth at the distribution transformer?

  1. To increase the supply voltage at the consumer end
  2. To prevent current from flowing in the phase conductor
  3. To fix the neutral near earth potential and allow protective devices to operate on earth faults Correct answer.
  4. To make the neutral carry the full load current

Explanation

Earthing the neutral at the source fixes the neutral at approximately earth potential, giving a defined reference for the phase voltage. It also creates a low-impedance return path so that an earth fault produces enough current to trip the fuse or MCB.

Question 21Basic Electrical Fundamentals and Safety

A coil draws 5 A at 230 V and dissipates 575 W. What is its power factor?

  1. 1.0
  2. 0.75
  3. 0.5 Correct answer.
  4. 0.25

Explanation

Apparent power is V × I = 230 × 5 = 1150 VA, and the power factor is real power divided by apparent power, 575/1150 = 0.5. A purely resistive load would give a power factor of 1.0.

Question 22Basic Electrical Fundamentals and Safety

In a series circuit of three unequal resistors, which quantity is the same through every resistor?

  1. Voltage across each resistor
  2. Current through each resistor Correct answer.
  3. Power dissipated in each resistor
  4. Resistance of each resistor

Explanation

A series circuit offers only one path, so the same current must pass through every element. Voltage, power, and resistance differ between resistors according to their values.

Question 23Basic Electrical Fundamentals and Safety

A 100 W lamp and a 60 W lamp, both rated for the same supply voltage, are connected in series across that supply. Which lamp glows brighter and why?

  1. The 100 W lamp, because it has the higher power rating
  2. The 60 W lamp, because its higher resistance drops more voltage at the common current Correct answer.
  3. Neither glows, because series connection prevents current flow
  4. Both glow equally, because the same current flows through each

Explanation

In series the current is common, and brightness depends on the actual power I²R in each lamp. The 60 W lamp has the higher resistance, so it dissipates more power and glows brighter, even though its rating is lower. Ratings apply only at the designed voltage when each lamp is used alone.

Question 24Basic Electrical Fundamentals and Safety

Why does a short circuit between live and neutral create a serious fire risk?

  1. It reduces the current to near zero and overheats the insulation
  2. It converts the supply into a higher-frequency alternating current
  3. It raises the circuit resistance and lowers the supply voltage
  4. It causes a very large current that heats conductors and may operate the protective device or ignite insulation Correct answer.

Explanation

A short circuit removes most of the circuit resistance, so the current rises to a value limited mainly by the source impedance and cable resistance. The resulting I²R heating can damage insulation and start a fire unless the fuse or MCB clears the fault quickly.

Question 25Electrical Tools, Instruments and Measuring Techniques

In an electrical workshop, which tool is specifically designed to hold and twist conductors while tightening terminal screws without damaging insulation?

  1. Long-nose pliers Correct answer.
  2. Wire stripper
  3. Ball-peen hammer
  4. Steel rule

Explanation

Long-nose pliers have tapered jaws that reach into confined terminal blocks and grip small conductors firmly, so the user can hold a wire steady while a screw is tightened. Their serrated jaws provide the controlled grip needed without crushing insulation, which is why they are standard in control-panel wiring work.

Question 26Electrical Tools, Instruments and Measuring Techniques

A candidate must tighten the small terminal screws inside a distribution board where fingers cannot reach. Which insulated tool is most appropriate for this task?

  1. Insulated combination pliers
  2. Insulated adjustable spanner
  3. Insulated hacksaw
  4. Insulated screwdriver Correct answer.

Explanation

An insulated screwdriver has a slim, VDE-rated shaft and a tip matched to the screw head, allowing the user to reach recessed terminal screws while the insulated handle and shaft reduce shock risk. Combination pliers, spanners and hacksaws are far too bulky for small recessed screws and are not designed to transmit torque to a screw slot.

Question 27Electrical Tools, Instruments and Measuring Techniques

Which instrument is used to measure the insulation resistance between two conductors of a wiring installation?

  1. Tong tester
  2. Wheatstone bridge
  3. Megger (insulation tester) Correct answer.
  4. Clamp meter

Explanation

An insulation tester, commonly called a megger, applies a high DC test voltage and measures the very high resistance of insulation in megohms. That high-voltage, high-resistance measurement is exactly what verifies that insulation between conductors or to earth is sound.

Question 28Electrical Tools, Instruments and Measuring Techniques

Before using a megger on a circuit, what is the essential safety step that must be carried out first?

  1. Increase the test voltage to the maximum range
  2. Connect the instrument to a live supply to check the display
  3. Short the test leads together to calibrate
  4. Isolate the circuit, lock off the supply and prove it is dead Correct answer.

Explanation

Insulation testing requires the circuit to be isolated and proved dead, otherwise the test voltage is applied to live equipment and the reading is meaningless. Locking off and proving dead protects the tester and the person, and it also prevents damage to connected electronic equipment.

Question 29Electrical Tools, Instruments and Measuring Techniques

Which accessory is fitted to a megger lead to make contact with a bare conductor during insulation testing?

  1. Test probe Correct answer.
  2. Crocodile clip
  3. Insulating tape
  4. Banana plug

Explanation

A test probe is the pointed hand-held contact that the operator touches to a bare conductor or terminal during insulation tests. Crocodile clips are used for temporary attachment to busbars or earth points, banana plugs connect the lead to the instrument, and tape is an insulating material, not a contact accessory.

Question 30Electrical Tools, Instruments and Measuring Techniques

A digital multimeter is set to the 20 V DC range and its display shows 1. This reading most likely indicates that:

  1. the meter is measuring AC instead of DC
  2. the measured value exceeds the selected range Correct answer.
  3. the leads are shorted together
  4. the battery is fully charged

Explanation

On most digital multimeters a leading 1 with no further digits is the over-range indication, meaning the input is larger than the selected range can display. The remedy is to move to a higher range or to autoranging, after confirming the meter is suited to the voltage present.

Question 31Electrical Tools, Instruments and Measuring Techniques

To measure the current drawn by a single lamp in a live circuit without breaking the connection, which instrument and method should be used?

  1. Megger connected across the lamp terminals
  2. Clamp meter with its jaws closed around one conductor Correct answer.
  3. Multimeter on the resistance range across the lamp
  4. Multimeter in series with the lamp

Explanation

A clamp meter senses the magnetic field produced by current in a conductor, so closing its jaws around one conductor gives a reading without interrupting the circuit. Clamping around both supply conductors would cancel the fields, so only the single conductor carrying the load current must be enclosed.

Question 32Electrical Tools, Instruments and Measuring Techniques

A clamp meter is closed around both the live and neutral conductors of a single-phase circuit carrying a load. The reading obtained will be approximately:

  1. Half the load current
  2. Zero, because the currents in the two conductors oppose each other Correct answer.
  3. The same as the load current
  4. Twice the load current

Explanation

In a healthy single-phase circuit the live and neutral currents are equal and flow in opposite directions, so their magnetic fields cancel inside the clamp jaws. The meter therefore reads close to zero, which is why clamp meters are used around one conductor at a time.

Question 33Electrical Tools, Instruments and Measuring Techniques

Which instrument uses a crossed-coil movement to indicate power directly by responding to both voltage and current?

  1. Induction energy meter
  2. Dynamometer wattmeter Correct answer.
  3. Moving-iron ammeter
  4. PMMC voltmeter

Explanation

A dynamometer wattmeter has a fixed current coil and a moving voltage coil, and the deflection depends on the product of the two coil currents, which is proportional to power. That crossed-coil arrangement is what makes direct power measurement possible on AC and DC circuits.

Question 34Electrical Tools, Instruments and Measuring Techniques

A single-phase load is measured with a wattmeter, and the current coil terminals are reversed by mistake while the voltage coil is connected correctly. The wattmeter pointer will:

  1. read the correct power
  2. deflect backwards below zero Correct answer.
  3. read zero
  4. read double the power

Explanation

Reversing the current-coil connection reverses the direction of the torque produced by the interaction of the two coil fields, so the pointer tries to move in the negative direction. The reading magnitude is still proportional to power, but the direction is wrong, so the coil must be reconnected correctly.

Question 35Electrical Tools, Instruments and Measuring Techniques

Which instrument is best suited for measuring the earth electrode resistance of an installation?

  1. Earth tester (fall-of-potential instrument) Correct answer.
  2. Clamp-on ammeter
  3. Frequency meter
  4. Insulation tester

Explanation

An earth tester injects a current between the electrode under test and a remote current spike and measures the potential difference with a second spike, giving electrode resistance by the fall-of-potential method. Insulation testers, clamp ammeters and frequency meters do not provide this four-terminal earth measurement.

Question 36Electrical Tools, Instruments and Measuring Techniques

A continuity test on a long cable run gives a reading of 0.4 ohm when the expected value is 0.1 ohm. Which factor most likely explains the difference?

  1. The cable being energised during the test
  2. The meter being set to the AC voltage range
  3. The meter having a low battery
  4. Resistance of the test leads and their contact with the terminals Correct answer.

Explanation

On low-resistance continuity tests the lead resistance and the quality of the probe contact can be a significant part of the total reading. The usual practice is to null or subtract the lead resistance, or use a four-wire measurement, before judging the cable itself.

Question 37Electrical Tools, Instruments and Measuring Techniques

Which of these describes the correct way to hold and use a steel rule when marking a cable tray for cutting?

  1. Support the rule only at one end and mark from the far edge
  2. Use the rule as a lever to bend the tray to the mark
  3. Lay the rule flat on the metal, mark with a scriber held at a slight angle, and read the graduations squarely Correct answer.
  4. Hold the rule at 45 degrees to the surface and mark with a pencil

Explanation

A steel rule should sit flat and fully supported on the work so the graduations are not distorted, and the eye should be directly above the mark to avoid parallax error. A scriber held at a slight angle produces a fine, accurate line without damaging the rule edge.

Question 38Electrical Tools, Instruments and Measuring Techniques

A vernier calliper is used to measure the diameter of a copper conductor. The main scale reads 3 mm and the 4th vernier division coincides with a main scale line. If the least count is 0.02 mm, the diameter is:

  1. 3.04 mm
  2. 3.40 mm
  3. 3.08 mm Correct answer.
  4. 3.20 mm

Explanation

The vernier reading equals the main scale reading plus the coinciding vernier division multiplied by the least count. Here 3 mm plus 4 times 0.02 mm gives 3.08 mm, which is the correct diameter.

Question 39Electrical Tools, Instruments and Measuring Techniques

A micrometer screw gauge has a pitch of 0.5 mm and a thimble with 50 divisions. Its least count is:

  1. 0.05 mm
  2. 0.1 mm
  3. 0.5 mm
  4. 0.01 mm Correct answer.

Explanation

The least count of a screw gauge is the pitch divided by the number of thimble divisions. Dividing 0.5 mm by 50 gives 0.01 mm, which is the smallest length the instrument can resolve directly.

Question 40Electrical Tools, Instruments and Measuring Techniques

A moving-coil ammeter with a full-scale deflection of 1 mA and a coil resistance of 100 ohm is to be used as a 10 V voltmeter. What series resistance is required?

  1. 9900 ohm Correct answer.
  2. 100 ohm
  3. 1000 ohm
  4. 10 ohm

Explanation

For full-scale deflection at 10 V the total circuit resistance must be 10 V divided by 1 mA, which is 10 000 ohm. Subtracting the 100 ohm coil resistance leaves 9900 ohm to be added in series as a multiplier.

Question 41Electrical Tools, Instruments and Measuring Techniques

A moving-coil meter with a full-scale current of 1 mA and a coil resistance of 100 ohm is to be converted into a 1 A ammeter. What shunt resistance is needed?

  1. Approximately 1 ohm
  2. Approximately 100 ohm
  3. Approximately 0.1 ohm Correct answer.
  4. Approximately 10 ohm

Explanation

The shunt must carry the remaining 0.999 A while the meter carries 1 mA at full-scale voltage of 0.1 V. Dividing 0.1 V by 0.999 A gives approximately 0.1 ohm, so a very low shunt value is required to extend the current range.

Question 42Electrical Tools, Instruments and Measuring Techniques

A megger reading taken between two phases of a motor winding falls below the manufacturer's minimum acceptable value. What is the correct interpretation?

  1. The insulation resistance is too low and the winding should be investigated before energising Correct answer.
  2. The meter leads are faulty and the reading has no meaning
  3. The winding is healthy and can be energised immediately
  4. The test voltage was too high and the reading should be ignored

Explanation

A reading below the specified minimum indicates degraded insulation, which may be caused by moisture, contamination or damage. The winding should be dried, cleaned and retested, and the equipment must not be energised until the value is acceptable.

Question 43Electrical Tools, Instruments and Measuring Techniques

Which precaution protects a digital multimeter when it is used to check the presence of mains voltage at a socket outlet?

  1. Select the current range and connect the probes in parallel
  2. Select the correct AC voltage range and confirm the meter's CAT rating before probing Correct answer.
  3. Select the continuity range and probe the socket
  4. Select the resistance range and probe the socket

Explanation

Voltage measurement requires the AC voltage function with a range above the expected supply voltage, and the meter's category rating must be adequate for the installation. Using a resistance or current range on a live socket can blow the meter's fuse or destroy the instrument and endanger the user.

Question 44Electrical Tools, Instruments and Measuring Techniques

A moving-iron instrument is preferred over a moving-coil instrument for measuring an AC supply current because the moving-iron movement:

  1. requires no damping system
  2. responds to the RMS value of both AC and DC without a rectifier Correct answer.
  3. operates only on direct current
  4. has a more linear scale than any other movement

Explanation

A moving-iron movement deflects according to the square of the current, so on AC it indicates the RMS value directly and works equally on DC. A moving-coil movement responds to average value and needs a rectifier to indicate AC, which is why moving-iron types are common in panel ammeters.

Question 45Domestic Wiring, Accessories and Installation Practice

In a domestic single-phase installation, which conductor colour identification is used for the earth (protective) conductor in a flexible three-core cable?

  1. Solid blue
  2. Solid black
  3. Green with yellow stripe Correct answer.
  4. Solid brown

Explanation

Indian domestic wiring practice identifies the protective earth conductor by green insulation with a yellow stripe, so it can never be confused with a live or neutral core. Black and blue are used for neutral, and brown for the phase conductor.

Question 46Domestic Wiring, Accessories and Installation Practice

A socket outlet in a domestic circuit must be rated so that the plug top fuse protects the connected flexible cord. Which rated current is the standard value for a 6 A domestic socket outlet used for lighting and small appliances?

  1. 32 A
  2. 63 A
  3. 16 A
  4. 6 A Correct answer.

Explanation

The common domestic socket outlet for lighting and small appliances is rated 6 A and is protected by a matching 6 A plug top fuse. Higher ratings such as 16 A are reserved for power circuits feeding heavier appliances.

Question 47Domestic Wiring, Accessories and Installation Practice

When wiring a three-pin domestic socket outlet, the earth pin is deliberately made longer and thicker than the other two pins. What is the practical purpose of this design?

  1. It prevents the plug from being inserted in the dark
  2. It reduces the voltage drop at the appliance terminals
  3. It increases the current-carrying capacity of the socket
  4. It ensures the earth connection is made first and broken last Correct answer.

Explanation

The longer earth pin enters the socket first and leaves last, so the appliance is earthed before the live and neutral contacts close. This ordering protects the user during insertion and withdrawal of the plug.

Question 48Domestic Wiring, Accessories and Installation Practice

In a domestic wiring installation, which protective device is intended to disconnect the supply when current leaks from the live conductor to earth through a person or wet surface?

  1. Metal oxide surge arrester
  2. Rewirable fuse
  3. Miniature circuit breaker
  4. Residual current circuit breaker Correct answer.

Explanation

A residual current circuit breaker senses the imbalance between live and neutral currents and trips at a low leakage value, typically 30 mA for personal protection. An MCB or fuse responds to overload and short-circuit current, not small earth leakage.

Question 49Domestic Wiring, Accessories and Installation Practice

A domestic lighting sub-circuit is to be wired with copper conductor. Which conductor size is the standard minimum permitted for a lighting circuit in Indian domestic installation practice?

  1. 4.0 sq mm
  2. 0.5 sq mm
  3. 1.0 sq mm Correct answer.
  4. 6.0 sq mm

Explanation

Domestic lighting circuits are normally wired with 1.0 sq mm copper conductor, which carries the small lighting load with adequate mechanical strength. Sizes of 4.0 and 6.0 sq mm are used for power circuits and sub-mains.

Question 50Domestic Wiring, Accessories and Installation Practice

While installing a conduit run for domestic wiring, a draw box is provided at a bend. Which reason correctly explains why a draw box is placed there?

  1. To provide an additional earthing point
  2. To increase the current rating of the circuit
  3. To house the energy meter connections
  4. To permit pulling of conductors through the bend without damage Correct answer.

Explanation

A draw box at a bend or at a long straight run gives access for pulling wires and for jointing, so conductors are not abraded against the bend. It is an access point, not a current-rating or earthing device.