Free Journeyman Electrician’s General Questions and Answers — Questions and Answers
Question 1: Conductors with marks on the insulation are NOT approved for use in a wet location.
- THWN
- THW
- THHW
- THHN (Correct answer)
Correct answer: THHN
Table 310.104(A) shows that conductors with THHN insulation are approved for use in dry and damp locations only, and conductors with THWN, THHW, and THW insulation are recognized for service in dry and wet areas.
Question 2: Given: A one-family dwelling unit with a demand load of 200 amperes is supplied with a 120/240 volt, single-phase electrical system from the local utility company. What are the MINIMUM size aluminium THW conductors required for use as service-entrance conductors for this residence?
- 2/0 AWG
- 1/0 AWG
- 4/0 AWG (Correct answer)
- 3/0 AWG
Correct answer: 4/0 AWG
Section 310.15(B)(7)(1) permits one-family dwelling 120/240 volt, single-phase, service-entrance conductors to be sized at an ampacity of not less than 83% of the service rating. <br>
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Therefore, 200 amperes x 83% = 166 amperes <br>
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Aluminium conductors of size 4/0 AWG THW with a permissible ampacity of 180 amperes should be chosen for this residence, according to Table 310.15(B)(16).
Question 3: Where a 150 kVA, a single-phase transformer with a secondary voltage of 120/240, is installed at a multi-family dwelling, the secondary's full-load current rating, in amperes, is ___.
- 1250 amperes
- 625 amperes (Correct answer)
- 265 amperes
- 526 amperes
Correct answer: 625 amperes
To find the full-load current rating of the single-phase transformer apply the single-phase current formula as shown: <br>
<br>
I = (150 kVA x 1000) / 240 volts = 15,000/240 = 625 amperes
Question 4: Which circuit breakers mentioned below do NOT have a conventional ampere rating?
- 90 amperes
- 75 amperes (Correct answer)
- 225 amperes
- 110 amperes
Correct answer: 75 amperes
Table 240.6(A) illustrates the standard ampere ratings for fuses and circuit breakers. A circuit breaker with an ampere rating of 75 amperes is not a common ampere rating.
Question 5: The MINIMUM length of the free conductor to be left at each junction box for splicing conductors or making connections to luminaires or devices shall be ____ .
- 8 inches
- 4 inches
- 10 inches
- 6 inches (Correct answer)
Correct answer: 6 inches
According to Section 300.14, each junction box must have at least 6 inches of open conductors available for splices or connecting luminaires or other devices. This guideline aims to ensure enough conductor slack for the terminal connections or splices to be made easily.
Question 6: Conductors for overhead service drops should generally not be any smaller than.
- 4 AWG copper
- 2 AWG copper
- 8 AWG copper (Correct answer)
- 6 AWG copper
Correct answer: 8 AWG copper
Section 230.23(B) requires overhead service-drop wires to be not smaller than 8 AWG copper or 6 AWG aluminium or copper-clad aluminium. Refrain from mistake service-entrance conductors, the conductors from the utility company's service point to the service disconnecting mechanism, with service-drop conductors, the overhead conductors between the utility electric supply system and the service point.
Question 7: The NEC mandates that a galvanized eye bolt be installed at least ____ above the completed grade to serve as the connection point for electrical service.
- 15 ft.
- 8 ft.
- 10 ft. (Correct answer)
- 12 ft.
Correct answer: 10 ft.
The purpose of Section 230.26 is to ensure that conductors have adequate vertical clearance, avoid physical damage to the conductors, and shield people from unintentional contact with the conductors that could result in shock or electrocution. The service-drop conductors' attachment point must always be 10 feet above the finished grade.
Question 8: The wires connecting the final branch circuit overcurrent device to the service equipment, an independently derived system, or another power source
- Service conductor
- Feeder (Correct answer)
- Service drop
- Branch circuit
Correct answer: Feeder
A feeder is a set of conductors that carries electrical power from the main service panel or a separately derived source to subpanels, distribution panels, or other loads within a building or facility. Feeder conductors connect to the branch circuit overcurrent devices and provide power to various circuits throughout the building. Feeder conductors are usually larger in size than branch circuit conductors to accommodate higher currents and longer distances.
Question 9: Continuous load is defined as a load when the maximum current is anticipated to last for _____ hours or more:
Correct answer: 3
Continuous load is defined as a load where the maximum current is anticipated to last for 3 hours or more. This definition is important in electrical design and calculations to ensure that wiring and equipment are properly sized to handle sustained loads without overheating or causing safety issues.
Question 10: Personal doors must open in the direction of egress and have the indicated panic hardware for equipment with an 800 A or higher rating that is placed less than ___ from the nearest edge of the working space:
- 12 ft.
- 15 ft.
- 25 ft. (Correct answer)
- 6 ft.
Correct answer: 25 ft.
Personal doors must open in the direction of egress and have the indicated panic hardware for equipment with an 800 A or higher rating that is placed less than 25 feet from the nearest edge of the working space. This requirement helps ensure safe and unobstructed exit paths for personnel in case of emergencies.
Question 11: The largest electrical trade size that IMC will approve is :
- 6 in.
- 8 in.
- 5 in.
- 4 in. (Correct answer)
Correct answer: 4 in.
The largest electrical trade size that Intermediate Metal Conduit (IMC) will typically approve is 4 inches. IMC is a type of conduit used for electrical wiring installations, and its size can vary depending on the application and specific requirements, but 4 inches is often the maximum size available for IMC.
Question 12: Each box, cabinet, conduit body, or other termination must have a flexible metal conduit (FMC) secured within ____ of it:
- 18 in.
- 15 in.
- 12 in. (Correct answer)
- 6 in.
Correct answer: 12 in.
Each box, cabinet, conduit body, or other termination must have a flexible metal conduit (FMC) secured within 12 inches of it. This requirement ensures that FMC is properly supported and secured to prevent strain on connections and to maintain the integrity of the electrical installation.
Question 13: The maximum distance from any receptacles must be ___ along the horizontal floor line of any wall space:
- 12 ft.
- 6 ft. (Correct answer)
- 4 ft.
- 3 ft.
Correct answer: 6 ft.
The maximum distance from any receptacles must be 6 feet along the horizontal floor line of any wall space. This requirement helps ensure that electrical receptacles are conveniently located for the use of portable appliances and devices within a space.
Question 14: Which of the following branch circuits must have receptacles with a grounding type?
- 15 A
- 20 a
- Both 15 A or 20 A (Correct answer)
- None of the answer is correct
Correct answer: Both 15 A or 20 A
Both 15 A and 20 A branch circuits must have receptacles with a grounding type. Grounding is an important safety feature that helps protect against electrical shock and provides a path for fault currents to safely discharge. Therefore, receptacles on both 15 ampere and 20 ampere branch circuits must be of the grounding type to ensure proper safety standards are met.
Question 15: For industrial and commercial buildings, the required lighting load is ___ volt amperes per square foot:
Correct answer: 2
For industrial and commercial buildings, the required lighting load is typically 2 volt-amperes per square foot (VA/ft²). This value is used as a guideline to determine the lighting load for different spaces within these types of buildings. However, lighting requirements may vary based on local building codes and specific applications.
Question 16: For 12 AWG copper conductor, the maximum overcurrent protection is:
- 25 Amperes
- 15 Amperes
- 20 Amperes (Correct answer)
- 30 Amperes
Correct answer: 20 Amperes
For a 12 AWG copper conductor, the maximum overcurrent protection is typically 20 amperes. This value corresponds to the ampacity of a 12 AWG copper conductor as specified by standard electrical codes. It's important to follow the appropriate codes and regulations for your specific application to ensure safe and compliant electrical installations.
