FREE Journeyman Electrician’s MCQ Questions and Answers
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?
How should a single equipment grounding conductor be scaled when it is connected to many branch circuits in the same 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.
What is the resistance of 80 watt Light bulb rated at 120 volts?
To calculate the resistance of a light bulb, you can use Ohm's Law:
Resistance (R) = Voltage (V) / Current (I)
Given that the light bulb is rated at 80 watts and 120 volts, you can find the current using the formula for power:
Power (P) = Voltage (V) × Current (I)
Solving for current:
Current (I) = Power (P) / Voltage (V) = 80 W / 120 V = 0.666... A (approximately)
Now, you can use Ohm's Law to find the resistance:
Resistance (R) = Voltage (V) / Current (I) = 120 V / 0.666... A ≈ 180 ohms
So, the resistance of the 80-watt light bulb rated at 120 volts is approximately 180 ohms.
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?
What kind of substance shouldn't be utilized for grounding electrodes.
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.
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.
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.
Which of the circuit breakers mentioned below DOES NOT have a conventional ampere rating?
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.
The following places are not permitted to utilize flexible cards:
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.
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.
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?
What is the maximum ampacity that a No. 1/0 THWN copper conductor can handle when installed in 107° F of ambient temperature?
What should the overcurrent device rating in the panel board be if the panel board has a rating of 100 amperes?
The over current device rating must not be greater than panel board rating in which it is located
What is the sinusoidal AC low voltage contact limit?
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.
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 _____.
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
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?
What proportion of the emergency load's rated voltage should a storage battery give at a minimum?
A storage battery used for emergency loads should be able to provide at least 87.5% of the rated voltage of the emergency load.