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California General Electrician practice questions and answers
20 free questions from our 300-question California General Electrician bank, each with the correct answer, explanation, and source note. Official format: 100 multiple-choice questions · 70% to pass · 4.5-hour limit · supplied electronic references.
Wiring methods
1. An electrician is running wiring through a commercial hallway ceiling with exposed pendant lighting. Which raceway is the most practical choice for this exposed application?
Answer: C. The keyed answer is "EMT (Electrical Metallic Tubing)". EMT is lightweight, easy to bend, and approved for exposed work in commercial buildings. NM-B is limited to dry, concealed locations in residential wood-frame construction. This item tests wiring_methods in the context of NEC 358.10 — Installation: Wiring Methods: EMT Use. Apply the rule only under the conditions stated in the stem, and compare the distractors with the keyed answer before using the rule in a different situation.
Source: NEC 358.10 — Installation: Wiring Methods: EMT Use
Grounding and bonding
2. A new residential service is being installed. What is the minimum size copper grounding electrode conductor required for a 200-amp service?
Answer: C. Table 250.66 sizes the grounding electrode conductor from the largest ungrounded service conductor. A 200-amp residential service typically uses 2/0 or 3/0 AWG copper, and for service conductors of 2/0 through 3/0 AWG the table requires a 4 AWG copper GEC. 6 AWG is only permitted for 1/0 AWG or smaller service conductors.
Source: NEC Table 250.66 — Grounding: Grounding Electrode Conductor Sizing
Boxes conduit
3. During rough-in inspection, the inspector flags a junction box that appears too small. The box contains six 12 AWG conductors, two device pigtails, and one device clamp. What is the minimum cubic-inch volume required?
Answer: C. The keyed answer is "21.0 in³". Six 12 AWG conductors at 2.25 in³ each equals 13.5 in³, plus two device pigtails at 2.25 in³ (4.5 in³), plus one internal clamp at 2.25 in³ equals 20.25 in³, rounded up to 21.0 in³ minimum box fill. This item tests boxes_conduit in the context of NEC 314.16(B) — Installation: Boxes and Conduit Bodies: Box Fill Calculations. Apply the rule only under the conditions stated in the stem, and compare the distractors with the keyed answer before using the rule in a different situation.
Source: NEC 314.16(B) — Installation: Boxes and Conduit Bodies: Box Fill Calculations
Conductor sizing
4. A 40-amp, 240-volt branch circuit feeds a wall oven. What is the minimum conductor size for copper conductors with 75°C insulation?
Answer: A. Table 310.16: 8 AWG copper is rated 50 amps at 75°C, which is sufficient for a 40-amp circuit; 10 AWG (35 A at 75°C) is too small. 6 AWG would work but is not the minimum. The 60°C column (40 A for 8 AWG) only governs where terminations are not rated 75°C.
Source: NEC 310.16 — Conductors: Allowable Ampacities
Overcurrent protection
5. A kitchen dishwasher is connected to a dedicated branch circuit. The manufacturer specifies a 15-amp breaker. Can the electrician install a 20-amp overcurrent device instead?
Answer: C. The keyed answer is "No, the manufacturer's listed overcurrent protection must be followed". Manufacturer listing requirements take precedence. The NEC requires that equipment be installed per its listing, which includes the specified overcurrent protection rating. This item tests overcurrent_protection in the context of NEC 110.3(B) — Installation: Equipment Listing: Manufacturer Instructions. Apply the rule only under the conditions stated in the stem, and compare the distractors with the keyed answer before using the rule in a different situation.
Source: NEC 110.3(B) — Installation: Equipment Listing: Manufacturer Instructions
Motors
6. A 5-horsepower, 230-volt, single-phase pool pump motor has a Table 430.248 full-load current of 28 amps. What is the minimum size copper THWN branch-circuit conductor (75°C terminations)?
Answer: A. NEC 430.22 requires branch-circuit conductors for a single motor to have an ampacity of at least 125% of the motor full-load current from Table 430.248: 28 × 1.25 = 35 amps. 10 AWG copper THWN is rated 35 amps at 75°C in Table 310.16, so 10 AWG is the minimum; 8 AWG (50 A) is larger than required.
Source: NEC 430.22 — Motors: Branch Circuit Conductors
Load calculations
7. A dwelling unit has a 240-volt, 12-kW electric range. Using the standard calculation method, what is the demand load for the range?
Answer: C. Table 220.55, Column C: for one household range rated not over 12 kW, the standard-method demand load is 8 kW. The 12 kW nameplate is not used directly, and Note 1 (5% per kW over 12 kW) does not apply to a 12 kW range.
Source: NEC 220.55 — Load Calculations: Household Electric Ranges
Service sizing
8. A small commercial office has 120 general-use receptacles at 180 VA each, 40 fluorescent luminaires at 150 VA each, and one 208V, 3-phase air-conditioning unit with a nameplate of 7,000 VA. What is the calculated service load using the standard method?
Answer: C. Receptacles: 120 × 180 VA = 21,600 VA; Table 220.44 allows the first 10 kVA at 100% and the remainder at 50%, so 10,000 + 5,800 = 15,800 VA. Lighting: 40 × 150 VA = 6,000 VA at 100%. Air conditioning: 7,000 VA at 100%. Total = 15,800 + 6,000 + 7,000 = 28,800 VA, or 28.8 kVA.
Source: NEC 220.44 — Receptacle Loads: Nondwelling Demand Factors
Voltage drop
9. A 100-amp subpanel is located 300 feet from the main panel. The load is 80 amps at 240 volts single-phase. Using 2/0 AWG copper conductors, what is the approximate voltage drop?
Answer: D. Single-phase voltage drop = 2 × K × I × D ÷ CM, with K = 12.9 for copper, I = 80 A, D = 300 ft and 2/0 AWG = 133,100 circular mils: 2 × 12.9 × 80 × 300 ÷ 133,100 ≈ 4.65 volts. 4.65 ÷ 240 = 1.9%, within the 3% recommended for feeders in the informational note to 215.2.
Source: NEC 90.0(A) — Installation: Purpose: Adequacy of Wiring
Safety
10. Before servicing a 480-volt industrial motor starter, what must an electrician perform to ensure a safe working condition?
Answer: B. The keyed answer is "Wear rubber gloves and begin working immediately". NFPA 70E requires lockout/tagout of all energy sources before working on energized or potentially energized equipment. A non-contact tester alone is insufficient and rubber gloves are PPE, not a substitute for LOTO. This item tests safety in the context of NFPA 70E 120.5 — Safety: Establishing an Electrically Safe Work Condition. Apply the rule only under the conditions stated in the stem, and compare the distractors with the keyed answer before using the rule in a different situation.
Source: NFPA 70E 120.5 — Safety: Establishing an Electrically Safe Work Condition
Maintenance
11. An electrician is troubleshooting a circuit that trips intermittently. The multimeter shows normal voltage at the panel but the breaker trips under light load. What tool would best identify the fault?
Answer: D. The keyed answer is "Megohmmeter". A megohmmeter tests insulation resistance and can detect degraded insulation that causes intermittent ground faults. A clamp meter measures current but cannot identify insulation breakdown. This item tests maintenance in the context of NEC 110.5 — Maintenance: Conductors: General. Apply the rule only under the conditions stated in the stem, and compare the distractors with the keyed answer before using the rule in a different situation.
Source: NEC 110.5 — Maintenance: Conductors: General
Wiring methods
12. NM-B cable is being installed in a new single-family home. In which of the following locations is NM-B prohibited?
Answer: C. The keyed answer is "Below a concrete slab-on-grade foundation". NM-B cable cannot be installed in wet locations or below grade. A concrete slab-on-grade is a wet location where NM cable is not permitted without additional protection. This item tests wiring_methods in the context of NEC 334.12(A) — Wiring Methods: Uses Permitted: Wet Locations. Apply the rule only under the conditions stated in the stem, and compare the distractors with the keyed answer before using the rule in a different situation.
Source: NEC 334.12(A) — Wiring Methods: Uses Permitted: Wet Locations
Grounding and bonding
13. A metallic water pipe enters a building and is bonded to the grounding system. How far from the building entrance must the bonding connection be made to the water pipe?
Answer: D. The keyed answer is "Within 5 feet of the pipe's entry into the building". The bonding jumper to a metallic water pipe must be connected within 5 feet of the point of entrance into the building to ensure an effective ground-fault current path. This item tests grounding_and_bonding in the context of NEC 250.68(C)(1) — Grounding Electrode Conductor Connections: Metal Water Pipe. Apply the rule only under the conditions stated in the stem, and compare the distractors with the keyed answer before using the rule in a different situation.
Source: NEC 250.68(C)(1) — Grounding Electrode Conductor Connections: Metal Water Pipe
Boxes conduit
14. An electrician needs to pull four 10 AWG THHN conductors through a 3/4-inch EMT raceway. Is this installation permitted?
Answer: D. The keyed answer is "Yes, because 3/4-inch EMT has sufficient fill for four 10 AWG conductors". Per NEC Chapter 9 Table 1, 3/4-inch EMT at 40% fill has a cross-sectional area of 0.213 in². Four 10 AWG THHN conductors at 0.0211 in² each equals 0.0844 in², which is well within the allowable fill. This item tests boxes_conduit in the context of NEC Chapter 9, Table 1 — Installation: Conduit Fill. Apply the rule only under the conditions stated in the stem, and compare the distractors with the keyed answer before using the rule in a different situation.
Source: NEC Chapter 9, Table 1 — Installation: Conduit Fill
Conductor sizing
15. A feeder serves a 200-amp subpanel. The conductors are copper with 75°C insulation and terminate on equipment rated for 75°C. What is the minimum conductor size?
Answer: D. Table 310.16: 3/0 AWG copper at 75°C is rated 200 amps, so it is the smallest size that carries a 200-amp feeder; 2/0 AWG is only 175 amps. (310.12 allows 2/0 copper only for a 200-amp dwelling service or feeder that supplies the entire dwelling load, which this subpanel feeder does not.)
Source: NEC 310.16 — Conductors: Allowable Ampacities
Overcurrent protection
16. A 100-amp fused disconnect protects a heat pump. The equipment label specifies a maximum fuse size of 60 amps. Can the electrician install 60-amp fuses in a 100-amp rated disconnect?
Answer: D. The keyed answer is "Yes, the overcurrent device must not exceed the equipment's listed rating". The disconnect can be rated higher than the overcurrent device. The fuse size must match the equipment's listed maximum, not the disconnect's rating, per the equipment listing. This item tests overcurrent_protection in the context of NEC 240.60(A) — Overcurrent Protection: Enclosed Fuses. Apply the rule only under the conditions stated in the stem, and compare the distractors with the keyed answer before using the rule in a different situation.
Source: NEC 240.60(A) — Overcurrent Protection: Enclosed Fuses
Motors
17. A 10-horsepower, 230-volt, 3-phase motor has a Table 430.250 full-load current of 28 amps. What is the maximum rating of an inverse-time circuit breaker for motor branch-circuit short-circuit and ground-fault protection?
Answer: D. Table 430.52 allows an inverse-time breaker of up to 250% of the motor full-load current: 28 × 2.5 = 70 amps, which is a standard size in 240.6(A). Where 250% does not land on a standard size, 430.52(C)(1) Exception 1 permits the next standard size up.
Source: NEC 430.52 — Motors: Branch-Circuit Short-Circuit Protection
Load calculations
18. A dwelling has four 120V, 20-amp branch circuits for general lighting. Using the optional calculation method, what is the demand load for the general lighting in VA?
Answer: D. Four circuits × 120 V × 20 A = 9,600 VA. Under the optional method in 220.82(B), the general loads are taken at 100% for the first 10 kVA and 40% for the remainder. 9,600 VA is under 10 kVA, so the full 9,600 VA applies.
Source: NEC 220.82(B) — Optional Calculation: Dwelling Unit General Loads
Service sizing
19. A 2,000-square-foot dwelling has two 240V, 40A electric clothes dryers. What is the demand load for the dryers using the standard calculation?
Answer: A. The keyed answer is "10.0 kW". Per NEC 220.54, two dryers are calculated at 5.0 kW each using Table 220.54 Column C for two or more dryers, totaling 10.0 kW. This item tests service_sizing in the context of NEC 220.54 — Load Calculations: Electric Dryers. Apply the rule only under the conditions stated in the stem, and compare the distractors with the keyed answer before using the rule in a different situation.
Source: NEC 220.54 — Load Calculations: Electric Dryers
Voltage drop
20. A sign installer needs to run a 240V, 20-amp circuit 300 feet to a rooftop sign. Using 8 AWG copper THHN, what is the voltage drop at full load?
Answer: A. The keyed answer is "9.6 volts (4.0%)". Voltage drop = 2 × 12.9 × 20 × 300 / 16,510 = 9.36 volts, approximately 4.0% of 240V. This exceeds the recommended 3% for branch circuits and may require upsizing conductors. This item tests voltage_drop in the context of NEC 90.0(A) — Installation: Purpose: Voltage Drop Considerations. Apply the rule only under the conditions stated in the stem, and compare the distractors with the keyed answer before using the rule in a different situation.
Source: NEC 90.0(A) — Installation: Purpose: Voltage Drop Considerations
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