Journeyman Electrician Practice Test 21

Question 1: What connects the equipment grounding conductors and the service-disconnect enclosure to the grounded conductor inside each service disconnect enclosure?

• An unspliced main bonding jumper
• A grounding electrode conductor
• The neutral bar alone, with no jumper
• A supply-side bonding jumper

NEC Reference: NEC 250.24(B)

Question 2: A metal elbow is installed in an underground PVC service raceway, with at least 18 in. of cover over every part of the elbow. Must the elbow be connected to the grounded conductor?

• Yes, every metal part of a service must be bonded
• Only if the elbow is larger than trade size 2
• Only if the service is rated more than 200 A
• No; an isolated elbow with 18 in. of cover is exempt

NEC Reference: NEC 250.80 Exception

Question 3: A ground rod is driven at a pole light and connected to the equipment grounding conductor (an auxiliary electrode). Which statement is true?

• It must be bonded to the building electrode system
• Its resistance must be 25 ohms or less
• It replaces the need for an EGC to the pole
• The earth may not be used as the fault-current path

NEC Reference: NEC 250.54

Question 4: How may the metal structural frame of a building be used in the grounding electrode system?

• To interconnect electrodes, or as a GEC
• Only if it is painted with conductive paint
• It may not be used for grounding at all
• Only as an equipment grounding conductor

NEC Reference: NEC 250.68(C)(2)

Question 5: A building is supplied by a feeder from an outdoor transformer (separately derived system). When may a system bonding jumper be installed at both the transformer and the building's first disconnect?

• Only if the transformer is rated over 112.5 kVA
• Never; only one system bonding jumper is ever allowed
• Whenever the feeder is longer than 100 ft
• Only if no parallel neutral path is created

NEC Reference: NEC 250.30(A)(1) Exception No. 2

Question 6: Four 60-watt lamps operate on a 120-volt circuit. What is the total current?

• 0.5 A
• 2 A
• 4 A
• 8 A

Question 7: On a 120/240-volt, 3-wire single-phase feeder, line L1 carries 30 A and line L2 carries 20 A of 120-volt loads. What current flows in the neutral?

• 50 A
• 25 A
• 10 A
• 0 A

Question 8: A 100 kW load operates at 0.70 power factor. How many kVAR of capacitors are needed to raise the power factor to 0.90?

• 48.4 kVAR
• 53.6 kVAR
• 102.0 kVAR
• 142.9 kVAR

Question 9: A one-family dwelling needs outdoor receptacle outlets at the front and back, readily accessible from grade. Not more than how high above grade may they be?

• 5 ft
• 5½ ft
• 6½ ft
• 8 ft

NEC Reference: NEC 210.52(E)(1)

Question 10: A dwelling basement has a finished family room and two separate unfinished areas (a storage room and a workshop). How many receptacle outlets are required at minimum in the unfinished areas?

• One in each unfinished portion (2)
• One receptacle for the whole basement
• None; unfinished areas need no receptacles
• Four, one on each wall of every room

NEC Reference: NEC 210.52(G)(3)

Question 11: A store has a 30 ft long show window. How many receptacle outlets are required directly above it, within 18 in. of the top of the window?

• 1
• 2
• 3
• 4

NEC Reference: NEC 210.62

Question 12: When the NEC gives a conductor size without stating the conductor material, which material does the size apply to?

• Copper
• Aluminum
• Copper-clad aluminum
• Any of them equally

NEC Reference: NEC 110.5

Question 13: What is the minimum number of entrances required to the working space around a 100 A panelboard?

• Two, if the panelboard is over 6 ft wide
• None, if the space is open
• Two, one at each end
• One entrance of sufficient area

NEC Reference: NEC 110.26(C)(1)

Question 14: A separately installed pressure connector (such as a splicing block) is listed for 90 °C. At what temperature rating may the conductors connected to it be used?

• Not more than the connector's listed 90 °C rating
• Always 60 °C
• Any temperature, if the conductor is rated higher
• Always 75 °C

NEC Reference: NEC 110.14(C)(2)

Question 15: Where is a box or conduit body required?

• Only at receptacle and lighting outlets
• Only in exposed work, never in concealed work
• Only where conductors change direction in a run
• At every splice, outlet, switch, junction or pull point

NEC Reference: NEC 300.15

Question 16: At points where the armor of Type AC cable terminates, what must be provided in addition to a fitting?

• A bonding jumper to the nearest water pipe
• An insulating bushing (anti-short)
• Two wraps of electrical tape around the conductors
• A grounding pigtail to the nearest box screw

NEC Reference: NEC 320.40

Question 17: A 400 A feeder uses two parallel sets of copper THWN conductors with 75 °C terminations. What is the smallest conductor permitted in each set?

• 2/0 AWG
• 3/0 AWG
• 4/0 AWG
• 250 kcmil

NEC Reference: NEC 310.10(G) and Table 310.16

Question 18: A 60 A, 240-volt circuit breaker must have its ampere rating marked where?

• On a paper tag tied to the breaker handle
• Molded or stamped on its handle or escutcheon
• Only on the panelboard circuit directory
• Only on the shipping carton or packaging

NEC Reference: NEC 240.83(B)

Question 19: On a 208Y/120-volt, 4-wire system, may three single-pole 120/240-volt breakers with identified handle ties protect a 3-phase, 208-volt line-to-line load?

• Yes; grounded neutral with 120 V to ground
• No; a 3-pole common-trip breaker is always required
• Yes, but only when they supply motor loads
• Only on 480Y/277-volt systems, never on 208Y/120

NEC Reference: NEC 240.15(B)(3)

Question 20: A motor has two disconnecting means: one at the controller and one at the motor. What does 430.107 require?

• Both must be inside locked electrical rooms
• Both of them must be readily accessible
• Neither one needs to be accessible
• At least one must be readily accessible

NEC Reference: NEC 430.107

Question 21: What is the minimum size copper THWN branch-circuit conductor (75 °C terminations) for a 40 hp, 460-volt, 3-phase motor?

• 8 AWG
• 6 AWG
• 4 AWG
• 3 AWG

NEC Reference: NEC 430.22, Table 430.250 and Table 310.16

Question 22: The disconnecting means for a power production source (such as an interconnected PV system) must:

• Open only the grounded (neutral) conductor
• Be located only inside the inverter enclosure
• Open all ungrounded conductors together
• Be operable only with a special tool

NEC Reference: NEC 705.20

Question 23: A dwelling has a power inlet installed for connecting a portable generator to an optional standby system. What does 702.7(C) require at the inlet?

• A lockbox to secure the generator cord
• A GFCI receptacle mounted beside the inlet
• No marking of any kind is required at the inlet
• A sign: bonded- or floating-neutral generator

NEC Reference: NEC 702.7(C)

Question 24: Lamps used for general illumination on a construction site must be:

• LED type only, because they run cooler
• Protected by a luminaire or guarded lampholder
• Rated at least 300 W each to light the area
• Installed at least 10 ft above the working floor

NEC Reference: NEC 590.4(F)

Question 25: Threaded conduit enters an explosionproof enclosure through an NPT threaded entry. At least how many threads must be fully engaged?

• 3
• 4
• 5
• 7

NEC Reference: NEC 500.8(E)

Question 26: A surface-mounted switch is installed outdoors in a wet location. What enclosure is required?

• None, as long as it is a GFCI-type switch
• A standard indoor box with a plastic cover
• A weatherproof enclosure per 312.2
• Any metal box with a blank metal cover

NEC Reference: NEC 404.4(A)

Question 27: Recessed parts of a luminaire NOT identified for contact with insulation must be spaced at least how far from combustible materials (other than at points of support and trim)?

• ¼ in.
• ½ in.
• 1½ in.
• 3 in.

NEC Reference: NEC 410.116(A)(1)

Question 28: Drywall around a flush-mounted box is broken. The gap between the drywall and the edge of the box must be repaired so it is not greater than:

• 1/2 in.
• 1/4 in.
• 1/8 in.
• 1/16 in.

NEC Reference: NEC 314.21

Question 29: Power distribution blocks may be installed in pull and junction boxes only if the box volume exceeds:

• 50 cu in.
• 75 cu in.
• 100 cu in.
• 150 cu in.

NEC Reference: NEC 314.28(E)

Question 30: May materials be stored in a transformer vault?

• No; nothing may be stored in the vault
• Yes, but only spare parts for the transformer
• Yes, if the vault is protected by sprinklers
• Yes, as long as they are noncombustible

NEC Reference: NEC 450.48