CEA NEC Code and Calculations 3 — Questions and Answers
Question 1: Under the NEC, what is the minimum burial depth for rigid metal conduit (RMC) under a residential driveway?
- 6 inches (Correct answer)
- 12 inches
- 18 inches
- 24 inches
Correct answer: 6 inches
NEC Table 300.5 specifies 6 inches minimum cover for RMC under a residential driveway.
Question 2: What does the NEC require regarding GFCI protection for all 125-volt, 15- and 20-ampere receptacles in a bathroom?
- All bathroom receptacles must be GFCI-protected (Correct answer)
- Only receptacles within 3 feet of the sink need GFCI
- GFCI is only required if there is no ventilation fan
- Only receptacles on the countertop need GFCI
Correct answer: All bathroom receptacles must be GFCI-protected
NEC 210.8(A)(1) requires GFCI protection for all 125-volt, 15- and 20-ampere receptacles in bathrooms.
Question 3: A circuit has a resistance of 12 ohms and a voltage of 120 volts. What is the current using Ohm's Law?
- 10 amperes (Correct answer)
- 1,440 amperes
- 0.1 amperes
- 108 amperes
Correct answer: 10 amperes
Ohm's Law: I = V ÷ R = 120 ÷ 12 = 10 amperes.
Question 4: According to the NEC, what minimum headroom must be maintained in front of electrical equipment rated 600 volts or less?
- 6.5 feet (2.0 m) (Correct answer)
- 5 feet
- 7 feet
- 4 feet
Correct answer: 6.5 feet (2.0 m)
NEC 110.26(A)(3) requires a minimum headroom of 6.5 feet in front of service equipment, panelboards, and similar equipment.
Question 5: Which NEC article covers grounding and bonding requirements?
- Article 250 (Correct answer)
- Article 310
- Article 230
- Article 200
Correct answer: Article 250
NEC Article 250 covers all grounding and bonding requirements for electrical systems.
Question 6: Under the NEC, what size copper equipment grounding conductor (EGC) is required for a 60-ampere circuit?
- 10 AWG (Correct answer)
- 12 AWG
- 8 AWG
- 6 AWG
Correct answer: 10 AWG
NEC Table 250.122 requires a minimum 10 AWG copper EGC for circuits protected at up to 60 amperes.
Question 7: What is the power (in watts) consumed by a 10-ohm resistor carrying 5 amperes?
- 250 watts (Correct answer)
- 50 watts
- 500 watts
- 2 watts
Correct answer: 250 watts
Power formula: P = I² × R = 5² × 10 = 25 × 10 = 250 watts.
CEA NEC Code and Calculations 3
Under the NEC, what is the minimum burial depth for rigid metal conduit (RMC) under a residential driveway?