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RME Board Exam practice questions

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Question 1Practical Electricity

A 12-volt source is connected across a 4-ohm resistor. What current flows through the resistor?

  1. 16 A
  2. 48 A
  3. 0.33 A
  4. 3 A Correct answer.

Explanation

Ohm's law states that current equals voltage divided by resistance. Substituting gives I = 12 V ÷ 4 Ω = 3 A.

Question 2Practical Electricity

An appliance draws 5 A from a 220-V supply. What is its power consumption?

  1. 1,100 W Correct answer.
  2. 44 W
  3. 0.023 W
  4. 225 W

Explanation

Electrical power in a resistive load equals voltage multiplied by current. P = 220 V × 5 A = 1,100 W.

Question 3Practical Electricity

In a series circuit, which quantity is the same through every component?

  1. Current Correct answer.
  2. Resistance
  3. Power
  4. Voltage

Explanation

A series circuit provides only one path for current, so the same current passes through every component. Voltage, resistance, and power can differ from one component to another.

Question 4Practical Electricity

In a parallel circuit, which quantity is the same across every branch?

  1. Current
  2. Resistance
  3. Voltage Correct answer.
  4. Power

Explanation

All parallel branches are connected across the same two nodes, so the voltage across each branch is identical. Current divides among the branches according to their resistances.

Question 5Practical Electricity

Which unit expresses electrical energy as billed by a utility?

  1. Ampere
  2. Ohm
  3. Kilowatt-hour Correct answer.
  4. Watt

Explanation

The kilowatt-hour is a unit of energy equal to one kilowatt used for one hour. Utility meters integrate power over time and register consumption in kilowatt-hours.

Question 6Practical Electricity

Under the Philippine Electrical Code, which color is used to identify the grounded conductor of a branch circuit?

  1. White or gray Correct answer.
  2. Red
  3. Black
  4. Green

Explanation

The grounded circuit conductor is identified by a white or natural gray finish. Green is reserved for equipment grounding, while black and red are commonly ungrounded conductors.

Question 7Practical Electricity

What is the primary purpose of a fuse in an electrical circuit?

  1. To open the circuit on excessive current Correct answer.
  2. To convert AC to DC
  3. To regulate voltage
  4. To improve power factor

Explanation

A fuse contains a link that melts when current exceeds its rating, opening the circuit and protecting conductors and equipment from overcurrent. It does not regulate voltage or improve power factor.

Question 8Practical Electricity

A kilowatt-hour meter connected at a service entrance measures which quantity?

  1. Energy consumed over time Correct answer.
  2. Circuit current
  3. Instantaneous power
  4. Voltage level

Explanation

A kilowatt-hour meter integrates power over time, so it records the total electrical energy consumed. Instantaneous power is read with a wattmeter, current with an ammeter, and voltage with a voltmeter.

Question 9Practical Electricity

Three resistors of 6 Ω, 9 Ω, and 15 Ω are connected in series. What is the total resistance?

  1. 3.6 Ω
  2. 10 Ω
  3. 15 Ω
  4. 30 Ω Correct answer.

Explanation

In a series circuit, total resistance is the sum of the individual resistances. R_total = 6 + 9 + 15 = 30 Ω.

Question 10Practical Electricity

Two 12-ohm resistors are connected in parallel. What is the equivalent resistance?

  1. 12 Ω
  2. 6 Ω Correct answer.
  3. 3 Ω
  4. 24 Ω

Explanation

For two equal resistors in parallel, the equivalent resistance is half of one resistor. R_eq = 12 ÷ 2 = 6 Ω.

Question 11Practical Electricity

A branch circuit carries 20 A and the total resistance of both circuit conductors is 0.5 Ω. What is the voltage drop?

  1. 40 V
  2. 20 V
  3. 0.025 V
  4. 10 V Correct answer.

Explanation

Voltage drop equals current multiplied by conductor resistance. VD = 20 A × 0.5 Ω = 10 V.

Question 12Practical Electricity

A continuous load of 30 A is supplied by a branch circuit. Applying the 125% continuous-load rule, what minimum conductor ampacity is required?

  1. 45 A
  2. 24 A
  3. 30 A
  4. 37.5 A Correct answer.

Explanation

Continuous loads must be sized at 125% of the load current for conductor ampacity. Required ampacity = 30 A × 1.25 = 37.5 A.

Question 13Practical Electricity

Which copper conductor is typically protected by a 20-A circuit breaker on a general-purpose receptacle branch circuit?

  1. No. 8 AWG
  2. No. 10 AWG
  3. No. 14 AWG
  4. No. 12 AWG Correct answer.

Explanation

A 20-A branch circuit is commonly wired with No. 12 AWG copper conductors. No. 14 AWG is normally protected at 15 A, No. 10 AWG at 30 A, and No. 8 AWG at 40 A or more.

Question 14Practical Electricity

A transformer has 500 primary turns and 50 secondary turns. If the primary is supplied at 220 V, what is the secondary voltage?

  1. 11 V
  2. 2,200 V
  3. 44 V
  4. 22 V Correct answer.

Explanation

Transformer voltage is proportional to turns ratio: V_secondary = V_primary × (N_secondary ÷ N_primary). V_s = 220 V × (50 ÷ 500) = 22 V.

Question 15Practical Electricity

A load draws 10 kVA at a power factor of 0.8. What is the real power?

  1. 10 kW
  2. 0.08 kW
  3. 12.5 kW
  4. 8 kW Correct answer.

Explanation

Real power equals apparent power multiplied by power factor. P = 10 kVA × 0.8 = 8 kW.

Question 16Practical Electricity

What is the main purpose of equipment grounding?

  1. To reduce energy consumption
  2. To clear faults safely Correct answer.
  3. To carry load current
  4. To improve voltage regulation

Explanation

Equipment grounding provides a low-impedance path for fault current so that the overcurrent device operates and clears the fault. The grounding conductor does not normally carry load current.

Question 17Practical Electricity

GFCI protection is required for receptacles installed in which location?

  1. Dining room
  2. Bathroom Correct answer.
  3. Living room
  4. Bedroom

Explanation

Receptacles in bathrooms are among the locations requiring ground-fault circuit-interrupter protection because of the presence of water and grounded surfaces. Bedrooms, living rooms, and dining rooms are not generally subject to this requirement.

Question 18Practical Electricity

A 5-HP single-phase motor operates at 230 V. Using 1 HP = 746 W and assuming 100% efficiency, what current does it draw?

  1. 23.0 A
  2. 10.8 A
  3. 16.2 A Correct answer.
  4. 5.0 A

Explanation

Convert horsepower to watts first: 5 HP × 746 W/HP = 3,730 W. Then I = P ÷ V = 3,730 ÷ 230 = 16.2 A.

Question 19Practical Electricity

A 1.5-kW heater runs 4 hours per day. At ₱12 per kWh, what is the cost of operating it for 30 days?

  1. ₱720
  2. ₱540
  3. ₱2,160 Correct answer.
  4. ₱180

Explanation

Energy = 1.5 kW × 4 h/day × 30 days = 180 kWh. Cost = 180 kWh × ₱12/kWh = ₱2,160.

Question 20Practical Electricity

What is the maximum percentage of conduit cross-sectional area that may be filled with conductors when three or more conductors are installed?

  1. 60%
  2. 40% Correct answer.
  3. 31%
  4. 53%

Explanation

The Philippine Electrical Code limits raceway fill to 53% for one conductor, 31% for two conductors, and 40% for three or more conductors. The 40% limit allows conductors to be pulled without damage.

Question 21Practical Electricity

A feeder supplies a connected load of 20 kW with a demand factor of 0.6. What is the demand load?

  1. 33.3 kW
  2. 20.6 kW
  3. 12 kW Correct answer.
  4. 0.03 kW

Explanation

Demand load equals connected load multiplied by the demand factor. Demand load = 20 kW × 0.6 = 12 kW.

Question 22Practical Electricity

A 120-V circuit develops a short circuit with a total resistance of 0.5 Ω. What fault current flows?

  1. 24 A
  2. 60 A
  3. 240 A Correct answer.
  4. 120 A

Explanation

The fault current is limited only by the circuit impedance, so I = V ÷ R. I = 120 V ÷ 0.5 Ω = 240 A.

Question 23Practical Electricity

A balanced three-phase load draws 50 A per line at 400 V line-to-line with a power factor of 0.85. What is the real power?

  1. 34.6 kW
  2. 51.0 kW
  3. 17.0 kW
  4. 29.4 kW Correct answer.

Explanation

For a balanced three-phase load, P = √3 × V_L × I_L × power factor. P = 1.732 × 400 × 50 × 0.85 ≈ 29.4 kW.

Question 24Practical Electricity

A three-phase feeder carries 100 A and each conductor has a resistance of 0.2 Ω. What is the line-to-line voltage drop?

  1. 60 V
  2. 34.6 V Correct answer.
  3. 20 V
  4. 17.3 V

Explanation

For a balanced three-phase feeder, line-to-line voltage drop is VD = √3 × I × R. VD = 1.732 × 100 × 0.2 ≈ 34.6 V.

Question 25Practical Electricity

Six current-carrying conductors are installed in a single conduit. What ampacity adjustment factor applies?

  1. 80% Correct answer.
  2. 50%
  3. 70%
  4. 90%

Explanation

The code adjustment factor for four to six current-carrying conductors in a raceway is 80% of the tabulated ampacity. Higher conductor counts require progressively lower factors.

Question 26Practical Electricity

A 24-volt DC source is connected across an 8-ohm resistor. What current flows?

  1. 192 A
  2. 3 A Correct answer.
  3. 32 A
  4. 0.33 A

Explanation

Ohm's law gives current as voltage divided by resistance. Substituting 24 V and 8 Ω gives 3 A.

Question 27Practical Electricity

Under the Philippine Electrical Code, which color identifies the equipment grounding conductor?

  1. Red
  2. Black
  3. White
  4. Green Correct answer.

Explanation

The equipment grounding conductor is identified by green, or green with a yellow stripe. White is used for the grounded circuit conductor, while black and red are commonly ungrounded conductors.

Question 28Practical Electricity

What is the primary function of a circuit breaker?

  1. To interrupt current during overloads and faults Correct answer.
  2. To raise the supply voltage for long feeders
  3. To record the energy consumed by a load
  4. To convert alternating current into direct current

Explanation

A circuit breaker automatically opens its contacts when current exceeds a safe value because of an overload or fault. It can then be reset after the problem is corrected.

Question 29Practical Electricity

A single-pole switch controlling a lamp should be connected in which conductor?

  1. Either circuit conductor, if marked
  2. The equipment grounding conductor
  3. The ungrounded circuit conductor Correct answer.
  4. The grounded circuit conductor

Explanation

The switch must open the ungrounded conductor so the lamp is de-energized when the switch is off. Switching the grounded conductor can leave the lamp connected to line potential.

Question 30Practical Electricity

A 120-V appliance draws 5 A. What is its power?

  1. 125 W
  2. 0.04 W
  3. 600 W Correct answer.
  4. 24 W

Explanation

For a resistive load, power equals voltage multiplied by current. Multiplying 120 V by 5 A gives 600 W.

Question 31Practical Electricity

Which metal is most commonly used for branch-circuit conductors because of its good conductivity and cost?

  1. Copper Correct answer.
  2. Iron
  3. Aluminum
  4. Silver

Explanation

Copper has low resistivity, good mechanical properties, and reasonable cost, so it is widely used for branch-circuit conductors. Silver has lower resistivity but is far too expensive for ordinary wiring.

Question 32Practical Electricity

What is the standard frequency of the low-voltage utilization system in the Philippines?

  1. 50 Hz
  2. 400 Hz
  3. 25 Hz
  4. 60 Hz Correct answer.

Explanation

The Philippine low-voltage utilization system operates at 60 Hz. This frequency is standard for ordinary lighting and power circuits in the country.

Question 33Practical Electricity

What is the main function of the grounding electrode conductor?

  1. It carries normal load current back to the source
  2. It limits current in the ungrounded conductors
  3. It bonds metal raceways to each other only
  4. It connects the grounded system to earth Correct answer.

Explanation

The grounding electrode conductor provides a intentional connection between the grounded system or equipment grounding system and the earth electrode. It helps stabilize voltage to earth and provides a path for certain fault and surge currents.

Question 34Practical Electricity

A step-down transformer has a turns ratio of 10:1. If the secondary current is 20 A, what is the primary current?

  1. 2 A Correct answer.
  2. 200 A
  3. 20 A
  4. 0.5 A

Explanation

For an ideal transformer, primary and secondary currents are inversely proportional to the turns ratio. A 10:1 step-down ratio means the primary current is one-tenth of the secondary current, or 2 A.

Question 35Practical Electricity

A plant has a lagging power factor. What is the effect of connecting power capacitors in parallel with the load?

  1. They reduce the line voltage at the load
  2. They increase the apparent power demand
  3. They reduce reactive current and improve power factor Correct answer.
  4. They increase the real power delivered to the load

Explanation

Capacitors supply reactive power locally, which offsets the lagging reactive power drawn by inductive loads. This reduces line current and improves the power factor.

Question 36Practical Electricity

Why is the neutral conductor of a grounded circuit not normally switched or fused?

  1. To reduce voltage drop in the circuit
  2. To keep the neutral continuous Correct answer.
  3. To allow neutral current to be interrupted
  4. To permit parallel neutral paths

Explanation

The grounded conductor is kept continuous so that opening a switch or blowing a fuse does not leave equipment connected to line potential through the neutral. Interrupting the neutral can create a hazardous condition.

Question 37Practical Electricity

A conductor has a tabulated ampacity of 100 A at 30°C. Using a correction factor of 0.87 for 40°C ambient, what is its corrected ampacity?

  1. 100 A
  2. 87 A Correct answer.
  3. 113 A
  4. 50 A

Explanation

Ambient temperature correction multiplies the tabulated ampacity by the correction factor. Multiplying 100 A by 0.87 gives 87 A.

Question 38Practical Electricity

When calculating box fill, how is a switch or receptacle yoke counted?

  1. As one conductor
  2. As three conductors
  3. As no conductor
  4. As two conductors Correct answer.

Explanation

Each yoke or strap containing one or more devices is counted as two conductors based on the largest conductor connected to the device. This accounts for the space taken by the device.

Question 39Practical Electricity

What does a motor overload relay primarily protect?

  1. The motor winding from overload Correct answer.
  2. The branch-circuit wiring from short circuits
  3. The circuit from ground faults
  4. Persons from electric shock

Explanation

An overload relay responds to sustained overcurrent that can overheat the motor winding. It is not intended to clear short circuits or ground faults; those are handled by branch-circuit protective devices.

Question 40Practical Electricity

AFCI protection is intended to detect which condition?

  1. Sustained overloads
  2. Reverse polarity
  3. Arc faults Correct answer.
  4. Ground faults to earth

Explanation

An arc-fault circuit interrupter detects characteristic arcing conditions in wiring and opens the circuit. It is intended to reduce the risk of fire from arc faults.

Question 41Practical Electricity

A copper conductor has a resistance of 10 Ω at 20°C. Using a temperature coefficient of 0.00393 per °C, what is its approximate resistance at 60°C?

  1. 10.0 Ω
  2. 15.7 Ω
  3. 11.6 Ω Correct answer.
  4. 8.4 Ω

Explanation

The temperature rise is 40°C, so the resistance increases by the factor 1 + 0.00393 × 40. This gives about 1.157 times 10 Ω, or approximately 11.6 Ω.

Question 42Practical Electricity

Two 6-Ω resistors are connected in parallel, and this combination is connected in series with a 4-Ω resistor. What is the total resistance?

  1. 16 Ω
  2. 7 Ω Correct answer.
  3. 10 Ω
  4. 3 Ω

Explanation

Two equal 6-Ω resistors in parallel have an equivalent resistance of 3 Ω. Adding the series 4-Ω resistor gives 7 Ω total.

Question 43Practical Electricity

Two resistors of 4 Ω and 8 Ω are connected in series across a 24-V source. What is the voltage across the 8-Ω resistor?

  1. 24 V
  2. 12 V
  3. 16 V Correct answer.
  4. 8 V

Explanation

The total series resistance is 12 Ω, so the current is 24 V ÷ 12 Ω = 2 A. The voltage across the 8-Ω resistor is 2 A × 8 Ω = 16 V.

Question 44Practical Electricity

A circuit breaker is marked 10 kAIC. What does this rating indicate?

  1. Normal trip setting of 10,000 A
  2. Fault-interrupting capacity of 10,000 A Correct answer.
  3. Maximum load current of 10,000 A
  4. Voltage rating of 10,000 V

Explanation

The interrupting rating tells the maximum available fault current the breaker can safely interrupt. A 10 kAIC breaker can clear a fault current up to 10,000 A without failing.

Question 45Practical Electricity

A balanced three-phase load draws 30 A per line at 400 V line-to-line. What is the apparent power?

  1. 20.8 kVA Correct answer.
  2. 24.0 kVA
  3. 12.0 kVA
  4. 9.6 kVA

Explanation

For a balanced three-phase load, apparent power is √3 × line voltage × line current. This gives √3 × 400 V × 30 A ≈ 20.8 kVA.

Question 46Practical Electricity

A load draws 100 kVA at a power factor of 0.6 lagging. How much capacitor kVAR is needed to raise the power factor to 0.8?

  1. 20 kVAR
  2. 45 kVAR
  3. 80 kVAR
  4. 35 kVAR Correct answer.

Explanation

The real power is 100 kVA × 0.6 = 60 kW. Initial reactive power is 80 kVAR, and at 0.8 power factor the required reactive power is 60 × tan(36.87°) = 45 kVAR, so the capacitors must supply about 35 kVAR.

Question 47Practical Electricity

A balanced three-phase, four-wire feeder carries 80 A in each phase conductor. What is the current in the neutral conductor?

  1. 46 A
  2. 138 A
  3. 80 A
  4. 0 A Correct answer.

Explanation

In a balanced three-phase system, the phase currents are equal in magnitude and displaced by 120°. Their phasor sum is zero, so the neutral current is zero.

Question 48Practical Electricity

A 10-HP, 230-V three-phase motor has a full-load current of 28 A. If the branch-circuit conductors must be sized at 125% of full-load current, what minimum ampacity is required?

  1. 30 A
  2. 28 A
  3. 35 A Correct answer.
  4. 32 A

Explanation

The required conductor ampacity is 125% of the motor full-load current. Multiplying 28 A by 1.25 gives 35 A.

Question 49Practical Electricity

A 240-V single-phase feeder carries 50 A and has a total voltage drop of 6 V in its conductors. What is the power lost in the conductors?

  1. 300 W Correct answer.
  2. 1,200 W
  3. 150 W
  4. 12,000 W

Explanation

The power lost in the conductors is the voltage drop multiplied by the current. Multiplying 6 V by 50 A gives 300 W.

Question 50Practical Electricity

A 12-V battery is connected across a 4-Ω resistor. What current flows through the resistor?

  1. 3 A Correct answer.
  2. 48 A
  3. 16 A
  4. 0.33 A

Explanation

Ohm's law states that current equals voltage divided by resistance. Substituting gives 12 V ÷ 4 Ω = 3 A.