Licensed Electrical Contractor Electrical Codes & Standards 3 — Questions and Answers
Question 1: Under NEC 310.15, which ambient temperature correction factor applies to THWN-2 conductors installed in an area where the ambient temperature is 50°C?
- 0.58 (Correct answer)
- 0.71
- 0.82
- 0.91
Correct answer: 0.58
For a 75°C-rated conductor (THWN-2) at 50°C ambient, NEC Table 310.15(B)(1) correction factor is 0.58.
Question 2: NEC Article 500 defines hazardous locations. A Class I, Division 2 location is best described as:
- A location where flammable gases are present continuously
- A location where flammable liquids are handled in open containers
- A location where flammable gases are not normally present but could exist under abnormal conditions (Correct answer)
- A location where combustible dust is present continuously
Correct answer: A location where flammable gases are not normally present but could exist under abnormal conditions
Class I, Division 2 covers locations where flammable vapors are handled but are not normally present in ignitable concentrations under normal conditions.
Question 3: According to NEC 230.79, the minimum ampacity required for a single-family dwelling service disconnect is:
- 60 amperes
- 100 amperes (Correct answer)
- 150 amperes
- 200 amperes
Correct answer: 100 amperes
NEC 230.79(C) requires a minimum 100-ampere service disconnect rating for a single-family dwelling.
Question 4: Under NEC 358.30, EMT must be secured within how many inches of each outlet box, junction box, or other termination?
- 18 inches
- 24 inches
- 30 inches (Correct answer)
- 36 inches
Correct answer: 30 inches
NEC 358.30(A) requires EMT to be secured within 3 feet (36 inches) of each box or termination.
Question 5: NEC 445.13 governs the ampacity of conductors for generators. The minimum conductor ampacity must be at least what percentage of the nameplate current rating?
- 100%
- 115% (Correct answer)
- 125%
- 150%
Correct answer: 115%
NEC 445.13 requires generator output conductors to have an ampacity of not less than 115% of the nameplate current rating.
Question 6: Which NEC article covers the installation requirements for transformer secondary conductors?
- Article 450 (Correct answer)
- Article 240
- Article 310
- Article 215
Correct answer: Article 450
NEC Article 450 covers transformers and transformer vaults, including secondary conductor installation requirements.
Question 7: Under NEC 680.22, a receptacle installed outdoors within 20 feet of a swimming pool must be:
- On a dedicated 20A circuit
- GFCI protected (Correct answer)
- AFCI protected
- At least 10 feet above grade
Correct answer: GFCI protected
NEC 680.22(A)(1) requires all receptacles within 20 feet of the inside wall of a pool to be GFCI protected.
Licensed Electrical Contractor Electrical Codes & Standards 3
Under NEC 310.15, which ambient temperature correction factor applies to THWN-2 conductors installed in an area where the ambient temperature is 50°C?