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Haryana BSEH Secondary NSQF Power study materials
Haryana BSEH Secondary NSQF Power study resources

Haryana BSEH Secondary NSQF Power practice questions

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Question 1Power Sector Overview and Career Pathways

In the Indian power sector, which organization is responsible for the integrated operation of the national power grid and for planning and monitoring transmission on an inter-state basis?

  1. Bureau of Energy Efficiency (BEE)
  2. Haryana Power Generation Corporation Limited (HPGCL)
  3. Grid Controller of India Limited (Grid-India) Correct answer.
  4. Central Electricity Regulatory Commission (CERC)

Explanation

Grid-India, formerly POSOCO, operates the National Load Despatch Centre and regional load despatch centres and oversees integrated grid operation across states. It is a distinct entity from the regulator and from generation companies.

Question 2Power Sector Overview and Career Pathways

A student wants to enter the power sector after Class 12 through an NSQF-aligned route. Which pathway best matches a technician-level job in power distribution?

  1. Pursuing a degree in journalism and then applying to a discom
  2. Taking a commerce degree and directly applying for a power plant engineer post
  3. Completing a hospitality course and applying for a billing clerk post in a discom
  4. Completing an ITI or diploma course in electrical trade and applying for lineman or substation attendant posts Correct answer.

Explanation

Technician roles such as lineman, substation attendant and meter reader are filled through electrical trade training at ITI or diploma level, which builds the required practical skill base. These qualifications map directly to NSQF levels used in power distribution recruitment.

Question 3Power Sector Overview and Career Pathways

Which of the following is a renewable energy source commonly harnessed in Haryana for grid-connected power generation?

  1. Diesel generator sets
  2. Solar photovoltaic plants Correct answer.
  3. Lignite-fired thermal steam cycle
  4. Coal-based supercritical boilers

Explanation

Solar photovoltaic plants convert sunlight directly into electricity and are a renewable source deployed at scale in Haryana. The other listed options are fossil-fuel based and are not renewable.

Question 4Power Sector Overview and Career Pathways

In the power sector value chain, what is the main function of a distribution company (discom)?

  1. Regulating tariffs and licensing transmission utilities
  2. Delivering electricity to end consumers and collecting revenue Correct answer.
  3. Transmitting bulk power across long inter-state corridors
  4. Generating electricity at high voltage in thermal plants

Explanation

A discom operates the distribution network that supplies consumers at utilization voltage and is responsible for metering, billing and revenue collection. Generation, bulk transmission and regulation are performed by other entities in the chain.

Question 5Power Sector Overview and Career Pathways

Which of these is a statutory body that approves tariffs for electricity supply in Haryana?

  1. Central Power Research Institute (CPRI)
  2. National Thermal Power Corporation (NTPC)
  3. Haryana Electricity Regulatory Commission (HERC) Correct answer.
  4. Haryana Vidyut Prasaran Nigam Limited (HVPNL)

Explanation

HERC is the state electricity regulatory commission that determines tariffs and issues regulations for the Haryana power sector. HVPNL is the state transmission utility, NTPC is a central generator and CPRI is a research institute.

Question 6Power Sector Overview and Career Pathways

A candidate is preparing for a lineman recruitment test in a Haryana discom. Which combination of subjects is most relevant for the written test?

  1. Income tax law, auditing and corporate accounting
  2. Marketing management and consumer behaviour
  3. Basic electrical theory, safety practices and knowledge of distribution equipment Correct answer.
  4. Civil construction drawing and quantity surveying only

Explanation

Lineman recruitment tests assess basic electrical principles, safety procedures and familiarity with poles, insulators, transformers and lines used in distribution. These directly reflect the duties of the post.

Question 7Power Sector Overview and Career Pathways

Why is load despatch considered important in power system operation?

  1. It decides the salary structure of utility employees.
  2. It approves new power purchase agreements between states.
  3. It matches generation to demand in real time to keep frequency within limits. Correct answer.
  4. It sets the retail tariff slab for domestic consumers.

Explanation

Load despatch balances generation against consumer demand continuously so that system frequency stays close to 50 Hz. This real-time balancing is essential for grid stability and equipment safety.

Question 8Power Sector Overview and Career Pathways

A village feeder in Haryana shows high technical losses. Which measure would most directly reduce these losses in the distribution network?

  1. Adding more unmetered connections
  2. Lowering the power factor by adding inductive loads
  3. Replacing undersized conductors and installing distribution transformers closer to load Correct answer.
  4. Increasing the length of bare low-voltage lines

Explanation

Technical losses fall when conductors are adequately sized and transformers sit near the load, reducing current and voltage drop. Longer thin lines and poor power factor both increase losses.

Question 9Power Sector Overview and Career Pathways

Which document in a power utility typically records the safety clearance given before work begins on an electrical line?

  1. Balance sheet
  2. Purchase order
  3. Permit to work Correct answer.
  4. Load survey report

Explanation

A permit to work formally records that the line has been isolated, earthed and declared safe before work starts. It is a core safety control in power utilities.

Question 10Power Sector Overview and Career Pathways

In the context of the power sector, what does the term 'open access' allow?

  1. Eligible consumers to use a transmission or distribution network of another utility on payment of charges Correct answer.
  2. Generators to set retail tariffs without regulatory approval
  3. Any consumer to bypass all metering requirements
  4. Discoms to disconnect consumers without notice

Explanation

Open access permits eligible consumers and generators to use existing transmission or distribution networks of other licensees by paying regulated charges. It promotes competition while network owners recover their costs.

Question 11Power Sector Overview and Career Pathways

Which of the following best describes the role of a smart meter in a modern distribution system?

  1. It steps down 11 kV to 415 V for the locality.
  2. It records and communicates consumption data remotely for billing and load management. Correct answer.
  3. It protects the transmission line against lightning surges.
  4. It stores coal for the generating station.

Explanation

A smart meter measures consumption and communicates readings to the utility, enabling remote billing, load monitoring and demand-side management. Voltage transformation and surge protection are functions of other equipment.

Question 12Power Sector Overview and Career Pathways

A candidate is comparing two career routes: a diploma in electrical engineering versus a short vocational certificate in electrical trade. Which statement is most accurate about how these routes affect career progression in the power sector?

  1. The certificate route leads directly to regulatory commission posts.
  2. The diploma route generally opens junior engineer and supervisory roles, while the certificate route typically leads to technician roles with scope for promotion through experience. Correct answer.
  3. Both routes are identical in duration and lead to the same job levels.
  4. The diploma route is irrelevant to power utilities and is useful only in banking.

Explanation

A diploma in electrical engineering usually qualifies a candidate for junior engineer or supervisory positions, whereas a vocational certificate prepares candidates for technician posts. Career growth from technician level is possible through experience and further qualification.

Question 13Power Sector Overview and Career Pathways

Why is power factor correction important for an industrial consumer connected to a distribution network?

  1. It increases the reactive power drawn from the grid.
  2. It changes the supply frequency from 50 Hz to 60 Hz.
  3. It eliminates the need for any metering at the consumer premises.
  4. It reduces reactive power demand and lowers current for the same active power. Correct answer.

Explanation

Correcting a low power factor reduces the reactive component of current, lowering line losses and improving voltage regulation. Utilities often charge penalties for poor power factor to encourage correction.

Question 14Power Sector Overview and Career Pathways

In a restructured power sector, what is the primary purpose of separating generation, transmission and distribution into distinct entities?

  1. To increase the number of employees in each organization
  2. To remove the need for any regulatory commission
  3. To introduce competition where feasible and regulate natural monopoly segments like transmission Correct answer.
  4. To ensure that all electricity is generated only from coal

Explanation

Unbundling allows competition in generation and supply while keeping transmission, a natural monopoly, under regulation. This structure aims to improve efficiency and consumer choice without compromising grid reliability.

Question 15Power Sector Overview and Career Pathways

A distribution utility notices that its aggregate technical and commercial (AT&C) losses are high. Which pair of factors most directly contributes to AT&C losses?

  1. Substation earthing resistance and relay settings
  2. Generator fuel quality and boiler efficiency
  3. Energy theft and poor billing collection efficiency Correct answer.
  4. Transmission line charging current and reactive compensation

Explanation

AT&C losses combine technical losses with commercial losses arising from theft, unmetered supply and weak collection efficiency. Billing and collection performance therefore directly shapes the AT&C figure.

Question 16Power Sector Overview and Career Pathways

A student argues that increasing renewable generation alone will solve the challenge of matching supply and demand. Which response best reflects the operational reality of the power system?

  1. Renewable plants cannot be connected to the grid at all.
  2. Variable renewables require flexibility from storage, demand response and conventional balancing resources to maintain grid stability. Correct answer.
  3. Grid frequency is irrelevant once renewables are added.
  4. Renewables are always available at full capacity, so no balancing is needed.

Explanation

Solar and wind output varies with weather and time of day, so the system needs flexibility options such as storage, demand response and flexible conventional generation. These maintain balance and frequency stability as renewable share rises.

Question 17Occupational Health, Safety and Environment (Electrical Safety)

In an electrical workshop, what is the primary purpose of earthing (grounding) the metal body of a machine?

  1. To raise the frame potential above the supply voltage
  2. To store excess charge in the machine frame during operation
  3. To provide a low-resistance return path so fault current trips the protective device quickly Correct answer.
  4. To increase the current drawn by the machine for better performance

Explanation

Earthing connects exposed metalwork to earth so that if a live conductor touches the frame, a large fault current flows and the fuse or MCB operates within a safe time. This limits the duration for which the frame stays at a dangerous potential. It does not improve machine performance or store charge.

Question 18Occupational Health, Safety and Environment (Electrical Safety)

A worker must switch off a 415 V motor circuit for maintenance. Which practice best satisfies the isolation requirement before work begins?

  1. Isolate at the breaker, lock and tag it, then prove dead with a tester Correct answer.
  2. Ask a colleague to watch the panel while you work
  3. Switch off at the local push button and start work immediately
  4. Reduce the load on the motor before touching the terminals

Explanation

Safe isolation requires positive disconnection, locking and tagging to prevent re-energisation, and proving the circuit dead at the point of work. Only then is the circuit safe to touch. A push button or verbal watch does not guarantee the supply cannot be restored.

Question 19Occupational Health, Safety and Environment (Electrical Safety)

Which class of fire extinguisher is appropriate for a live electrical panel fire in a workshop?

  1. Carbon dioxide (Class C/E) extinguisher Correct answer.
  2. Wet chemical extinguisher
  3. Water (Class A) extinguisher
  4. Foam (Class B) extinguisher

Explanation

Carbon dioxide extinguishers are non-conductive and leave no residue, so they suit fires involving energised electrical equipment. Water, foam and wet chemical agents conduct electricity and create a shock risk to the user. The supply should also be isolated where possible.

Question 20Occupational Health, Safety and Environment (Electrical Safety)

A technician finds a portable hand drill with a cracked casing and exposed internal wiring. What is the correct immediate action?

  1. Use it only for light drilling jobs on wood
  2. Withdraw it from service, tag it as defective, and report it Correct answer.
  3. Give it to a trainee who works at lower voltage
  4. Wrap the crack with insulation tape and continue using it

Explanation

Damaged portable tools must be taken out of service immediately, tagged to prevent use, and reported so that repair or replacement can be arranged. Taping a cracked casing does not restore mechanical or insulation integrity. Continued use exposes the operator to contact with live parts.

Question 21Occupational Health, Safety and Environment (Electrical Safety)

Why must the resistance of an earth electrode be kept low, typically below the value specified for the installation?

  1. To reduce the voltage drop across the supply transformer
  2. To improve the power factor of the connected motors
  3. To increase the insulation resistance of the wiring
  4. To keep touch voltage low and allow protective devices to operate quickly Correct answer.

Explanation

A low earth resistance limits the potential rise of earthed metalwork during a fault and allows enough fault current to flow to operate the protective device promptly. Both effects reduce the duration and magnitude of touch voltage exposure. It has no direct relation to power factor or wiring insulation.

Question 22Occupational Health, Safety and Environment (Electrical Safety)

An electrician is working on a circuit where the supply cannot be isolated. Which protective measure set is most appropriate?

  1. Cotton gloves, a metal ladder, and working alone to save time
  2. Wet cloth gloves and a wooden stool only
  3. Insulating gloves, insulated tools, and a rubber mat with a second person present Correct answer.
  4. Bare hands with careful movements and no mat

Explanation

Live work demands rated insulating gloves, insulated tools, an insulating mat or barrier, and a competent second person who can isolate and assist. These measures reduce the chance of body current and provide rescue capability. Working alone or with improvised materials is unacceptable.

Question 23Occupational Health, Safety and Environment (Electrical Safety)

What is the main hazard created by an electric arc flash during switching operations on a low-voltage panel?

  1. Intense radiant heat, molten metal droplets, and pressure blast Correct answer.
  2. Reduced magnetic field strength in the busbars
  3. A permanent increase in the panel's insulation resistance
  4. A slow rise in ambient humidity around the panel

Explanation

An arc flash releases intense radiant heat, vaporised metal and a pressure wave that can burn, blind and throw the operator. Arc-rated clothing and correct switching technique are used to reduce this risk. The other options describe irrelevant or reversed effects.

Question 24Occupational Health, Safety and Environment (Electrical Safety)

A residual current circuit breaker (RCCB) protecting a socket circuit should be tested at what interval by the user, and why?

  1. Monthly by pressing the test button, to confirm the trip mechanism operates Correct answer.
  2. Never, because testing damages the internal contacts
  3. Only after a shock has occurred, to record the event
  4. Once every five years, because the mechanism rarely ages

Explanation

The test button simulates a residual current and confirms that the trip mechanism is free and functional, so monthly operation is the usual user check. It does not test the full sensitivity of the device, which needs instrument testing, but it catches a stuck mechanism. Waiting for a shock defeats the purpose of protection.

Question 25Occupational Health, Safety and Environment (Electrical Safety)

Which factor most strongly determines the severity of electric shock to a worker's body?

  1. The colour of the insulation on the conductor
  2. The magnitude of current through the body and its duration Correct answer.
  3. The length of the cable run to the machine
  4. The number of sockets on the same circuit

Explanation

Body current magnitude and the time it flows are the dominant factors in shock severity, because they determine tissue damage and the likelihood of ventricular fibrillation. Voltage drives the current through body resistance, but current and duration are the direct physiological cause. Cable length, socket count and insulation colour do not determine injury severity.

Question 26Occupational Health, Safety and Environment (Electrical Safety)

A maintenance team must work on a distribution board fed from two sources. Which step best prevents back-feed hazard?

  1. Rely on the panel's 'off' indicator lamp
  2. Isolate only the main incoming breaker
  3. Disconnect the neutral bar only
  4. Isolate both sources and verify dead at the terminals of each Correct answer.

Explanation

Dual-supply boards can remain live from the second source or from a generator, so every source must be isolated and the terminals proved dead. An indicator lamp may be faulty or may monitor only one source. Isolating the neutral alone leaves phase conductors live.

Question 27Occupational Health, Safety and Environment (Electrical Safety)

Which of these is a correct use of a voltage tester before touching a conductor that should be dead?

  1. Use a neon screwdriver on the highest available range only
  2. Test the tester on a known live source, test the conductor, then re-test the tester Correct answer.
  3. Assume the conductor is dead if the breaker is off
  4. Touch the conductor with a bare finger to check for tingling

Explanation

Proving dead requires confirming the tester works before and after the test, so a failed tester cannot give a false 'dead' reading. Testing on a known live source validates the instrument. Assuming dead or using the body as a detector is dangerous.

Question 28Occupational Health, Safety and Environment (Electrical Safety)

In a TT earthing system, why is an RCD often required in addition to overcurrent protection?

  1. Because the RCD increases the supply voltage to the installation
  2. Because the RCD removes the need for any earth electrode
  3. Because the earth loop impedance is high and fault current may be too small to trip an MCB Correct answer.
  4. Because overcurrent devices cannot detect any fault current

Explanation

In a TT system the fault path returns through the soil and a local electrode, so loop impedance is relatively high and earth fault current may be below the MCB's trip threshold. An RCD responds to small residual currents and disconnects quickly. It does not replace the electrode or raise voltage.

Question 29Occupational Health, Safety and Environment (Electrical Safety)

A worker receives a shock from a machine and cannot let go. What should a rescuer do first?

  1. Isolate the supply or push the worker clear with a dry insulating object Correct answer.
  2. Pull the worker away with bare hands
  3. Wait for the worker to fall free before helping
  4. Throw water on the worker to break the contact

Explanation

The rescuer must break the contact safely, by switching off the supply or using a dry insulating object, before touching the casualty. Touching a person still in contact with a live conductor can pass current through the rescuer. Water and waiting increase harm.

Question 30Occupational Health, Safety and Environment (Electrical Safety)

Which statement correctly describes the function of a fuse in an electrical circuit?

  1. It disconnects the circuit when a person touches a live part
  2. It stores energy to smooth the supply waveform
  3. It limits the voltage reaching the load during normal operation
  4. It melts and opens the circuit when current exceeds its rating for a set time Correct answer.

Explanation

A fuse is a sacrificial element that melts when the current exceeds its rating, opening the circuit and protecting conductors from overheating. It responds to overcurrent, not to touch. Voltage regulation and energy storage are not its functions.

Question 31Occupational Health, Safety and Environment (Electrical Safety)

Which practice best reduces the risk of static electricity ignition when pouring flammable solvent in a workshop?

  1. Pour quickly to reduce the time solvent is exposed to air
  2. Warm the solvent to lower its viscosity
  3. Use a plastic funnel and a dry woollen cloth
  4. Bond and earth the container and receiving vessel before pouring Correct answer.

Explanation

Bonding and earthing equalise potential between containers so static charge cannot build up and spark at the pouring point. Fast pouring, insulating funnels and warming the liquid all increase charge generation or vapour release. The aim is to prevent a spark near flammable vapour.

Question 32Occupational Health, Safety and Environment (Electrical Safety)

What does an insulation resistance test on a de-energised motor winding primarily verify?

  1. That the supply voltage is within tolerance
  2. That the winding resistance to earth meets the specified minimum value Correct answer.
  3. That the motor will run at the correct speed under load
  4. That the bearings are correctly lubricated

Explanation

An insulation resistance test applies a DC voltage between the winding and earth to confirm the insulation is sound and above the specified minimum. It does not measure speed, supply voltage or bearing condition. The circuit must be isolated and proved dead before testing.

Question 33Occupational Health, Safety and Environment (Electrical Safety)

Why should extension leads be fully unwound from their drum before use with a heavy load?

  1. To prevent the cable from overheating due to trapped heat and inductive effects Correct answer.
  2. To increase the voltage at the far end beyond the supply value
  3. To reduce the current drawn by the connected appliance
  4. To make the cable easier to trip over

Explanation

A coiled cable cannot dissipate heat, and the coil also produces a magnetic field that adds inductive heating, so the cable can overheat and its insulation can fail. Unwinding allows heat to escape and keeps the cable within its rating. It does not raise voltage or reduce appliance current.

Question 34Occupational Health, Safety and Environment (Electrical Safety)

A workshop uses a 230 V portable grinder with a metal body and no earth conductor in its plug. What is the key risk?

  1. The grinder will draw excessive current during normal use
  2. The grinder will run at reduced speed
  3. The plug will overheat due to the missing earth pin
  4. A fault in the tool can leave the metal body live with no path to trip protection Correct answer.

Explanation

Without an earth conductor, a fault that connects the live conductor to the metal body leaves the body at full potential, and no fault current flows to operate the protective device. The user becomes the path to earth on contact. This is why such tools require double insulation or a 30 mA RCD.

Question 35Occupational Health, Safety and Environment (Electrical Safety)

Which item of personal protective equipment is essential when switching a low-voltage breaker that may produce an arc?

  1. A cotton cap and rubber sandals
  2. Arc-rated face shield and flame-resistant clothing Correct answer.
  3. Ordinary reading glasses and a woollen jersey
  4. A dust mask and safety goggles only

Explanation

Arc-rated face protection and flame-resistant clothing shield the head, face and body from radiant heat and molten droplets during switching. Cotton, wool and ordinary eyewear offer no arc rating and can ignite or melt. Standard eye protection alone does not protect against arc flash.

Question 36Occupational Health, Safety and Environment (Electrical Safety)

A factory plans to add a large motor to an existing feeder. Which calculation best checks that the cable will remain safe?

  1. Measure the cable's physical length and divide by the supply frequency
  2. Compare the motor's full-load current plus existing load against the cable's current-carrying capacity and protective device rating Correct answer.
  3. Check only that the cable colour matches the motor terminal colour
  4. Confirm that the motor nameplate voltage equals the cable voltage rating alone

Explanation

Cable safety depends on the total design current, the cable's tabulated current-carrying capacity after derating, and the protective device rating, which must sit between them. Checking only nameplate voltage or colour ignores thermal overload. Length and frequency division has no meaning here.

Question 37Occupational Health, Safety and Environment (Electrical Safety)

What is the correct action if a worker's clothing catches fire near an electrical panel after the supply has been isolated?

  1. Ask the worker to run to the nearest water tap
  2. Apply foam directly from a distance
  3. Fan the flames with a compressed air line
  4. Stop the worker, drop them to the ground and smother the flames with a fire blanket Correct answer.

Explanation

After isolation, the priority is to stop the casualty moving, get them down and smother the flames with a fire blanket or roll them on the floor. Running feeds oxygen to the flames, and compressed air spreads them. Cooling and medical help follow promptly.

Question 38Occupational Health, Safety and Environment (Electrical Safety)

Which condition makes a workplace electrical installation require a fresh risk assessment before work starts?

  1. The work involves a new live part, a changed circuit or unfamiliar equipment Correct answer.
  2. The shift starts at the usual time
  3. The tools are stored in the same cupboard as before
  4. The same team performed identical work last week

Explanation

A risk assessment must reflect the actual task, so a new live part, an altered circuit or unfamiliar equipment changes the hazards and controls. Repeating last week's work or unchanged storage and shift patterns do not by themselves introduce new electrical risk. The assessment is reviewed whenever conditions change.

Question 39Occupational Health, Safety and Environment (Electrical Safety)

Why is a 30 mA RCD considered supplementary protection rather than a substitute for earthing and insulation?

  1. Because it increases the earth loop impedance of the installation
  2. Because it only operates after a person has already received a shock current Correct answer.
  3. Because it disconnects the supply before any fault current flows
  4. Because it cannot detect any current imbalance in the circuit

Explanation

An RCD trips on residual current, which may already be flowing through a person's body, so it limits but does not prevent the shock. Earthing and sound insulation stop the fault arising or keep touch voltage low. RCDs are therefore an additional layer, not a replacement.

Question 40Occupational Health, Safety and Environment (Electrical Safety)

Which housekeeping practice best prevents electrical fires in a workshop?

  1. Using the area under a panel for solvent storage
  2. Storing oily rags and cardboard next to distribution boards
  3. Stacking spare cable drums against ventilation openings
  4. Keeping switchgear areas clear and free of combustible material Correct answer.

Explanation

Keeping switchgear and distribution boards clear of combustible material prevents a spark or hot surface from igniting nearby fuel. Oily rags, cardboard, cable drums and solvents are all potential fuels. Clear access also allows quick isolation in an emergency.

Question 41Occupational Health, Safety and Environment (Electrical Safety)

A trainee reports tingling when touching a metal switch plate. Which combination of checks is most appropriate?

  1. Increase the fuse rating to stop the tingling
  2. Check for a lost earth connection and measure touch voltage with the supply on, using proper precautions Correct answer.
  3. Ignore the report because tingling is normal in dry weather
  4. Replace the switch plate and assume the problem is solved

Explanation

Tingling at a metal plate suggests a fault path or a missing earth, so the earth continuity and touch voltage must be checked with suitable instruments and precautions. Ignoring it or simply replacing the plate leaves the underlying fault. Raising the fuse rating increases fire risk and does not remove the voltage.

Question 42Occupational Health, Safety and Environment (Electrical Safety)

According to standard electrical safety practice, what is the maximum rated residual operating current for an RCD used to protect socket outlets in a workshop?

  1. 500 mA
  2. 30 mA Correct answer.
  3. 100 mA
  4. 300 mA

Explanation

A 30 mA residual current device is the standard supplementary protection for socket circuits accessible to workers, because currents of that order are below the level likely to cause ventricular fibrillation in a healthy adult for short durations. Higher ratings such as 100 mA or 300 mA are used for fire protection or for selectivity in upstream devices, not for personal protection at socket outlets.

Question 43Occupational Health, Safety and Environment (Electrical Safety)

A worker must switch off a low-voltage distribution board known to contain a risk of arc flash. Which combination of measures best protects the worker at the moment of operation?

  1. Safety goggles and a hard hat, with the free hand resting on the panel frame
  2. Rubber gloves only, with the panel door held open by hand
  3. Cotton overalls and safety shoes, standing directly in front of the panel
  4. Arc-rated face shield and clothing, standing to the side of the panel with the body turned away Correct answer.

Explanation

Arc-rated PPE rated for the incident energy, combined with a body position to the side of the enclosure and the face turned away, minimises exposure of the head and torso to hot gases and molten metal ejected from the panel. Standard cotton clothing can ignite and worsen burn injury, and standing squarely in front places the worker directly in the ejection path.

Question 44Occupational Health, Safety and Environment (Electrical Safety)

During a site inspection, a portable hand lamp rated for use in a confined, damp metallic tank is being selected. Which supply arrangement is appropriate for this location?

  1. A 230 V hand lamp with a metal guard and an intact earth conductor
  2. A 230 V hand lamp protected only by a 30 mA RCD at the distribution board
  3. A battery hand lamp of any type held by a second worker standing outside the tank
  4. A hand lamp supplied at a reduced safety voltage such as 24 V from an isolating transformer Correct answer.

Explanation

In confined and damp conductive locations the touch voltage risk is high, so reduced low voltage supplied through an isolating transformer is the standard control, keeping the potential across the body low even if the lamp is damaged. A 230 V lamp, even earthed or RCD-protected, still exposes the worker to full mains potential in a location where contact with earthed metal is likely.

Question 45Occupational Health, Safety and Environment (Electrical Safety)

A maintenance engineer finds that a machine's metal enclosure becomes live only when a particular three-phase motor is running, and the enclosure is correctly bonded to the earthing system. Which fault condition best explains this observation?

  1. The earthing conductor has a high resistance, so the enclosure floats at a dangerous potential
  2. The motor windings have developed an insulation failure to the frame, energising the bonded enclosure Correct answer.
  3. The neutral conductor is broken upstream, causing the enclosure to carry load current
  4. The overcurrent device is undersized and trips only when the motor starts

Explanation

If the enclosure is properly bonded and becomes live only while that motor runs, the most likely cause is an insulation breakdown between the winding and the motor frame, which passes fault current into the bonding system. A high-resistance earth path would raise the potential of the whole bonded installation rather than only during that motor's operation, and a broken neutral or an undersized breaker would not by itself energise a bonded enclosure.

Question 46Occupational Health, Safety and Environment (Electrical Safety)

Before commencing work, a technician must prove that a circuit is dead. Which sequence correctly applies the test instrument?

  1. Test the circuit first, then confirm the instrument works on a known live source
  2. Test the instrument on a known live source, test the circuit, then re-test the instrument on the known source Correct answer.
  3. Test the circuit with the instrument set to the highest range, then isolate the supply
  4. Test the circuit, then rely on the indicator lamp on the panel to confirm isolation

Explanation

Proving dead requires confirming the tester is functioning both before and after the test on the circuit, so a failed instrument cannot give a false dead reading. Testing the circuit first, or trusting a panel indicator lamp, leaves the worker exposed if the tester or lamp is faulty.

Question 47Basic Electrical Principles and Units

Which SI base unit is used to express electric current in an NSQF electrical circuit problem?

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

Explanation

Electric current is an SI base quantity and its unit is the ampere, defined by the fixed numerical value of the elementary charge. Coulombs measure charge, volts measure potential difference and ohms measure resistance, so only the ampere expresses current itself.

Question 48Basic Electrical Principles and Units

A resistor of 12 ohm carries a current of 0.5 A. What is the potential difference across it?

  1. 12.5 V
  2. 6 V Correct answer.
  3. 0.04 V
  4. 24 V

Explanation

Ohm's law states V = I x R, so multiplying 0.5 A by 12 ohm gives 6 V. The other values come from multiplying instead of applying the law correctly or from dividing the quantities in the wrong order.

Question 49Basic Electrical Principles and Units

What is the SI unit of electrical resistance and how is it defined?

  1. Farad, one coulomb per volt
  2. Watt, one joule per second
  3. Ohm, one volt per ampere Correct answer.
  4. Siemens, one ampere per volt

Explanation

Resistance is defined by Ohm's law as the ratio of potential difference to current, so one ohm equals one volt per ampere. Siemens is the reciprocal unit of conductance, watt measures power and farad measures capacitance.

Question 50Basic Electrical Principles and Units

An electric iron rated 1000 W operates on a 250 V supply. What current does it draw?

  1. 4 A Correct answer.
  2. 0.25 A
  3. 2.5 A
  4. 250000 A

Explanation

Electrical power is given by P = V x I, so the current equals power divided by voltage, that is 1000 W divided by 250 V, giving 4 A. The other values come from multiplying the given figures or inverting the division.