Journeyman Electrician Practice Test
Journeyman Electrician Services & Overcurrent Protection Practice Questions
Services & Overcurrent Protection makes up 5 of every 50 questions on a Tigertest Journeyman Electrician practice test. Here are 10 of the 20 questions on it, each with the answer and the reason.
Updated by the Tigertest team. Based on the 2023 National Electrical Code (NFPA 70) and standard electrical theory. Original questions; 50 per test, 70% to pass. State licensing law not included.
1. What is the minimum service disconnect rating for a one-family dwelling?
- A.200 A
- B.100 A
- C.60 A
- D.150 A
Answer: B. A one-family dwelling service disconnect must be rated at least 100 A, three-wire. 60 A is the general minimum for other installations.
2. Where must the emergency disconnect for a one- or two-family dwelling service be located?
- A.In the attached garage
- B.Beside the water heater
- C.Inside next to the panel
- D.Readily accessible outdoors
Answer: D. One- and two-family dwelling services need an emergency disconnect at a readily accessible outdoor location so first responders can shut off power without entering.
3. Dwelling unit services must be provided with which type of surge protection?
- A.A Type 1 or Type 2 SPD
- B.An AFCI main breaker
- C.A Type 3 SPD only
- D.A GFCI main breaker
Answer: A. Services supplying dwelling units need a surge-protective device that is Type 1 or Type 2, integral to the service equipment or right next to it. Type 3 devices are point-of-use only.
4. Minimum clearance of overhead service conductors (300 V to ground or less) over a residential driveway not subject to truck traffic?
- A.15 ft
- B.18 ft
- C.12 ft
- D.10 ft
Answer: C. Overhead service conductors need 12 ft over residential property and driveways at 300 V to ground or less. Public streets and areas with truck traffic need 18 ft.
5. Where must the service disconnecting means be installed?
- A.At the center of the building
- B.At the farthest panelboard
- C.Nearest the conductors' entry point
- D.Within 25 ft of the meter
Answer: C. The service disconnect must be at a readily accessible location outside, or inside nearest the point of entrance of the service conductors. Some jurisdictions add a maximum distance, but the Code sets none.
6. Underground conductors between the utility's system and the service point are the:
- A.Service lateral
- B.Service mast
- C.Feeder tap
- D.Service drop
Answer: A. Article 100 defines the service lateral as the underground conductors between the utility electric supply system and the service point. The overhead version is the service drop.
7. Overhead service conductors run beside a window that opens must be kept at least how far from it?
- A.6 ft
- B.2 ft
- C.5 ft
- D.3 ft
Answer: D. Service conductors must have at least 3 ft of clearance from windows designed to be opened, doors, porches, balconies, ladders and similar locations. Conductors run above the top of a window are exempt.
8. Using the 83 percent rule for a 200 A dwelling service, what is the minimum copper service conductor?
- A.1/0 AWG copper
- B.2/0 AWG copper
- C.4/0 AWG copper
- D.3/0 AWG copper
Answer: B. Dwelling service conductors may be sized at 83 percent of the service rating: 200 x 0.83 = 166 A, and 2/0 copper is rated 175 A at 75°C. 4/0 is the aluminum size.
9. Which of these is NOT a standard ampere rating for fuses and inverse time circuit breakers?
- A.110 A
- B.65 A
- C.35 A
- D.45 A
Answer: B. Standard ratings run 15, 20, 25, 30, 35, 40, 45, 50, 60, 70, 80, 90, 100, 110, 125 and up. There is no 65 A standard size; the step goes from 60 to 70.
10. A conductor with an ampacity of 115 A supplies a load that needs 115 A. Up to 800 A, what is the largest overcurrent device allowed?
- A.115 A
- B.150 A
- C.110 A
- D.125 A
Answer: D. When the conductor ampacity does not match a standard size, the next higher standard rating may be used up to 800 A, as long as the conductors do not supply multioutlet receptacle circuits. The next size above 115 A is 125 A.
Practice all 20 services & overcurrent protection questions, and the rest of the 200-question bank, in the free Journeyman Electrician training sets. Questions you miss come back until you have mastered them.
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