Free Journeyman Electrician’s MCQ Questions and Answers — Questions and Answers
Question 1: Which of the following is true when Type NM cables are allowed to pass through a non-flexible raceway into a panelboard without being fastened to the panelboard?
- The number of cables installed in the raceway is not limited where the raceway length is not more than 24-inches.
- The raceway extends directly above the enclosure without penetrating the structural ceiling. (Correct answer)
- The cables must be strapped within 24 inches, measured along the cable sheath, of the outer end of the raceway because they are not fastened to the enclosure with a fitting.
- The raceway shall be at least 18-inches, but not more than 10 ft in length.
Correct answer: The raceway extends directly above the enclosure without penetrating the structural ceiling.
Type NM cable may pass through a non-flexible raceway into a panelboard unfastened when the raceway extends directly above the enclosure without penetrating a structural ceiling, serving simply as a cable sleeve. The other options misstate the NEC length limits and securing rules for this allowance.
Question 2: Which of the following four statements about the installation of receptacle outlets placed to serve countertop surfaces in the kitchen of a dwelling unit located in a multifamily home DOES NOT accurately express the code requirements?
- Only receptacle outlets installed within 6-inches of the outside edge of the sink(s) shall be required to be provided with ground-fault circuit-interrupter protection for personnel. (Correct answer)
- A receptacle outlet shall be installed at each wall counter space that is 12-inches or wider
- The required receptacle outlets shall be supplied by not less than two small-appliance branch circuits
- If located above, the receptacle outlets shall not be located more than 20-inches above the counter top.
Correct answer: Only receptacle outlets installed within 6-inches of the outside edge of the sink(s) shall be required to be provided with ground-fault circuit-interrupter protection for personnel.
This statement is the inaccurate one because GFCI protection is required for ALL receptacles serving kitchen countertop surfaces, not just those within 6 inches of the sink. The other statements correctly reflect NEC rules on receptacle spacing, the two small-appliance branch circuits, and the 20-inch height limit.
Question 3: Three Design B, 460-volt, three-phase, 1740 RPM alternating-current motors are supplied by a feeder. The motors' nameplate ratings are as follows: 15 horsepower, 18.2 amperes, 10.3 amperes, and 25 horsepower are the different power outputs. What size XHHW-2 copper feeder circuit wires are necessary to supply the motor load if all the motors are functioning continuously? The 75°C rating applies to the conductor terminations.
- 2 AWG
- 3 AWG
- 4 AWG (Correct answer)
- 6 AWG
Correct answer: 4 AWG
After applying the standard motor feeder calculation—125% of the largest motor's FLC plus 100% of the remaining motors' FLCs—the total load calls for 4 AWG copper based on the 75°C column for XHHW-2. Larger conductors (2 or 3 AWG) exceed what's required, while 6 AWG is too small to carry the calculated load.
Question 4: How should a single equipment grounding conductor be scaled when it is connected to many branch circuits in the same raceway or cable?
- The equipment grounding conductor shall be sized for the sum of all the overcurrent devices protecting the conductors in the raceway or cable.
- The equipment grounding conductor shall be sized for the average rating of all the overcurrent devices protecting the conductors in the raceway or cable.
- The equipment grounding conductor shall be sized for the largest overcurrent device protecting the conductors in the raceway or cable. (Correct answer)
- The equipment grounding conductor shall not be smaller than 10 AWG.
Correct answer: The equipment grounding conductor shall be sized for the largest overcurrent device protecting the conductors in the raceway or cable.
When a single equipment grounding conductor is connected to multiple branch circuits in the same raceway or cable, it should be sized based on the largest overcurrent device protecting the conductors in that raceway or cable. This ensures that the equipment grounding conductor can effectively carry fault currents in the event of a fault and provide proper grounding and safety for all the connected circuits.
Question 5: What is a transformer's maximum short-circuit fault current when the secondary nameplate rating is 75 kva, 120/240 volts, single-phase, and 2.5% Z?
- The maximum available short-circuit fault current:
- 312.5 (transformer full-load amperes) x 40 (multiplier) = 12,500 short-circuit fault current (Correct answer)
- The multiplier is 100 ÷ 2.5% = 40
- The transformer full-load ampere rating is 75000 ÷ 240 = 312.5
Correct answer: 312.5 (transformer full-load amperes) x 40 (multiplier) = 12,500 short-circuit fault current
The full-load secondary current is 75,000 ÷ 240 = 312.5 amperes, and the multiplier is 100 ÷ 2.5% = 40, so 312.5 × 40 = 12,500 amperes of short-circuit fault current. The other options each show only one intermediate step, while the correct answer combines them into the final result.
Question 6: What is a transformer's maximum short-circuit fault current when the secondary nameplate rating is 45 kva, 120/208 volts, three phases, and 1.2% Z?
- 125 (transformer full-load amperes) x 83.33 (multiplier) = 10416 (short-circuit fault current) (Correct answer)
- The transformer full-load ampere rating is 45000 ÷ (208 x 1.732) = 125
- The multiplier is 100 ÷ 1.2 = 83.33
- The maximum available short-circuit fault current:
Correct answer: 125 (transformer full-load amperes) x 83.33 (multiplier) = 10416 (short-circuit fault current)
For this three-phase transformer the full-load current is 45,000 ÷ (208 × 1.732) = 125 amperes, and the multiplier is 100 ÷ 1.2 = 83.33, giving 125 × 83.33 = 10,416 amperes of fault current. The other choices list only individual calculation steps rather than the complete final answer.
Question 7: What is the maximum ampacity that a No. 1/0 THWN copper conductor can handle when installed in 107° F of ambient temperature?
- 150 x .82 = 123 amperes (Correct answer)
- NEC Table 310.16 lists the allowable ampacity of No.1/0 THWN copper, a 75°C rated conductor as 150 amperes
- The correction factor is .82
Correct answer: 150 x .82 = 123 amperes
NEC Table 310.16 lists 1/0 THWN copper (75°C) at 150 amperes, and the temperature correction factor for 107°F ambient is 0.82, so 150 × 0.82 = 123 amperes. The other options give only the base ampacity or the correction factor alone without completing the adjusted ampacity.
Question 8: The following places are not permitted to utilize flexible cards:
- Ground fault circuit interceptor
- 4 AWG is the minimum size wire for a 300 ampere circuit
- To replace a fixed wiring of a structure (Correct answer)
- yes, to prevent unwanted gases entry in buildings
Correct answer: To replace a fixed wiring of a structure
Flexible cords are not permitted to be used as a substitute for the fixed wiring of a structure. They are designed for temporary connections, such as supplying power to portable appliances, equipment, or devices, and should not be used as a permanent wiring solution in place of proper fixed wiring installations. Using flexible cords in place of fixed wiring can pose safety hazards and increase the risk of fire or electrical accidents.
Question 9: What is the sinusoidal AC low voltage contact limit?
- 180 ohms
- 1/ 8 horse power
- 87 1/2 %
- 15 Volts RMS (Correct answer)
Correct answer: 15 Volts RMS
The sinusoidal AC low voltage contact limit is commonly considered to be around 15 volts RMS (Root Mean Square) to ensure safety when individuals come into contact with electrical systems or equipment. This level of voltage is generally considered to pose a low risk of causing harm.
Question 10: What kind of substance shouldn't be utilized for grounding electrodes.
- Iron
- Aluminum (Correct answer)
- Copper
- Steel
Correct answer: Aluminum
Aluminum is generally not recommended as a material for grounding electrodes in electrical systems. This is because aluminum tends to corrode more quickly compared to other metals like copper or galvanized steel when exposed to the elements and the surrounding environment. Corrosion can lead to an increase in the resistance of the grounding system, reducing its effectiveness. Copper and galvanized steel are commonly used for grounding electrodes due to their better corrosion resistance and conductivity.
Question 11: Which of the circuit breakers mentioned below DOES NOT have a conventional ampere rating?
- 14 AWG
- 625 amperes
- 75 amperes (Correct answer)
- THHN
Correct answer: 75 amperes
The standard ampere ratings for fuses and circuit breakers. A circuit breaker with an ampere rating of 75 amperes is not a standard ampere rating.
Question 12: What is the resistance of 80 watt Light bulb rated at 120 volts?
- 9.6 ohms
- 96 ohms
- 12.5 ohms
- 180 ohms (Correct answer)
Correct answer: 180 ohms
To calculate the resistance of a light bulb, you can use Ohm's Law: <br> Resistance (R) = Voltage (V) / Current (I) <br> Given that the light bulb is rated at 80 watts and 120 volts, you can find the current using the formula for power: <br> Power (P) = Voltage (V) × Current (I) <br> Solving for current: <br> Current (I) = Power (P) / Voltage (V) = 80 W / 120 V = 0.666... A (approximately) <br> Now, you can use Ohm's Law to find the resistance: <br> Resistance (R) = Voltage (V) / Current (I) = 120 V / 0.666... A ≈ 180 ohms <br> So, the resistance of the 80-watt light bulb rated at 120 volts is approximately 180 ohms.
Question 13: What proportion of the emergency load's rated voltage should a storage battery give at a minimum?
- 15 volts rms
- 87 2/3 %
- 87 6/11 %
- 87 1/2 % (Correct answer)
Correct answer: 87 1/2 %
A storage battery used for emergency loads should be able to provide at least 87.5% of the rated voltage of the emergency load.
Question 14: The vertically run metal wire-ways shall be surely supported at intervals not exceeding ............. ft of wire way and shall not have more than one joint between supports.
- 15 (Correct answer)
- Zero
- 10 ft
- 3
Correct answer: 15
The vertically run metal wireways shall be securely supported at intervals not exceeding 15 feet of wireway and shall not have more than one joint between supports.
Question 15: Where a 150 kVA, single-phase transformer having a secondary voltage of 120/240 is installed at a multi-family dwelling, the full-load current rating, in amperes, of the secondary is _____.
- 625 amperes (Correct answer)
- 75 amperes
- 14 AWG
- 24 inches
Correct answer: 625 amperes
To find the full-load current rating of the single-phase transformer apply the single-phase current formula as shown:I = (150 kVA x 1000) / 240 volts = 15,000/240 = 625 amperes
Question 16: What should the overcurrent device rating in the panel board be if the panel board has a rating of 100 amperes?
- 80 %
- 40 amperes
- less than 100 amperes (Correct answer)
- 6 AWG THWN Copper
Correct answer: less than 100 amperes
The over current device rating must not be greater than panel board rating in which it is located
Free Journeyman Electrician’s MCQ Questions and Answers
Which of the following is true when Type NM cables are allowed to pass through a non-flexible raceway into a panelboard without being fastened to the panelboard?