Licensed Electrical Contractor FREE Licensed Electrical Contractor Code, Theory, and Calculations Questions and Answers 2

Question 1

According to the NEC, what is the maximum allowable voltage drop recommended for branch circuits?

Accepted Answer

3%

Answer

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?

Accepted Answer

200 amps

Answer

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?

Accepted Answer

65%

Answer

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?

Accepted Answer

18 inches

Answer

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?

Accepted Answer

208 volts

Answer

The high leg in a three-phase four-wire delta system produces approximately 208 volts to neutral, calculated as 240 × 1.732 / 2.

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