Licensed Electrical Contractor FREE Licensed Electrical Contractor Code, Theory, and Calculations Questions and Answers 2 — Questions and Answers
Question 1: According to the NEC, what is the maximum allowable voltage drop recommended for branch circuits?
- 3% (Correct answer)
- 5%
- 7%
- 10%
Correct answer: 3%
The NEC recommends a maximum voltage drop of 3% for branch circuits and 5% total for feeder and branch circuits combined.
Question 2: What is the ampacity of a 3/0 AWG copper conductor with THWN insulation at 75°C?
- 200 amps (Correct answer)
- 175 amps
- 225 amps
- 150 amps
Correct answer: 200 amps
Per NEC Table 310.16, a 3/0 AWG copper conductor with 75°C insulation has an ampacity of 200 amps.
Question 3: When calculating commercial kitchen load, what demand factor does the NEC allow for six or more pieces of kitchen equipment?
- 65% (Correct answer)
- 80%
- 50%
- 75%
Correct answer: 65%
NEC Table 220.56 permits a 65% demand factor when there are six or more pieces of commercial kitchen equipment.
Question 4: What is the minimum burial depth for rigid metal conduit (RMC) under a one-family dwelling driveway?
- 18 inches (Correct answer)
- 24 inches
- 12 inches
- 6 inches
Correct answer: 18 inches
Per NEC Table 300.5, RMC requires a minimum burial depth of 18 inches under a one-family dwelling driveway.
Question 5: In a three-phase delta-connected system, what is the voltage between the high leg and the neutral?
- 208 volts (Correct answer)
- 240 volts
- 120 volts
- 277 volts
Correct answer: 208 volts
The high leg in a three-phase four-wire delta system produces approximately 208 volts to neutral, calculated as 240 × 1.732 / 2.
Question 6: What size equipment grounding conductor is required for a circuit protected by a 200-amp overcurrent device?
- 6 AWG copper (Correct answer)
- 4 AWG copper
- 8 AWG copper
- 2 AWG copper
Correct answer: 6 AWG copper
Per NEC Table 250.122, a 6 AWG copper conductor is the minimum equipment grounding conductor for a 200-amp overcurrent device.
Licensed Electrical Contractor FREE Licensed Electrical Contractor Code, Theory, and Calculations Questions and Answers 2
According to the NEC, what is the maximum allowable voltage drop recommended for branch circuits?