CEA NEC Code and Calculations 2 — Questions and Answers
Question 1: According to the NEC, what is the maximum voltage drop allowed for a branch circuit serving lighting loads?
- 3% (Correct answer)
- 5%
- 10%
- 2%
Correct answer: 3%
The NEC recommends a maximum voltage drop of 3% for branch circuits and 5% total for feeders and branch circuits combined.
Question 2: A 20-ampere, 120-volt branch circuit is limited to what maximum continuous load?
- 16 amperes (Correct answer)
- 20 amperes
- 15 amperes
- 18 amperes
Correct answer: 16 amperes
NEC 210.20 requires that continuous loads not exceed 80% of the branch circuit rating, so 20A × 80% = 16A maximum continuous load.
Question 3: What NEC article covers wiring methods and materials for general installations?
- Article 300 (Correct answer)
- Article 200
- Article 100
- Article 400
Correct answer: Article 300
NEC Article 300 covers general requirements for wiring methods and materials used in electrical installations.
Question 4: When calculating the load for a household electric dryer, the NEC requires a minimum demand of how many volt-amperes?
- 5,000 VA (Correct answer)
- 3,000 VA
- 7,500 VA
- 10,000 VA
Correct answer: 5,000 VA
NEC 220.54 requires a minimum load of 5,000 VA for each electric dryer when calculating feeder and service loads.
Question 5: Under NEC Article 210, a 15-ampere branch circuit is permitted to serve a maximum of how many general lighting receptacle outlets in a dwelling?
- No specific limit by count (Correct answer)
- 8 outlets
- 12 outlets
- 6 outlets
Correct answer: No specific limit by count
The NEC does not limit receptacle outlets by count on a branch circuit; load limits and circuit ampacity govern the design instead.
Question 6: What is the NEC standard for the maximum length of a flexible cord used as a wiring method?
- Flexible cords are not a permitted wiring method for permanent installations (Correct answer)
- 6 feet
- 10 feet
- 3 feet
Correct answer: Flexible cords are not a permitted wiring method for permanent installations
NEC 400.12 prohibits flexible cords from being used as a substitute for fixed wiring; they are not a permitted permanent wiring method.
Question 7: According to the NEC, what ampacity correction factor applies when four current-carrying conductors are bundled together?
- 80% (Correct answer)
- 70%
- 60%
- 90%
Correct answer: 80%
NEC Table 310.15(C)(1) requires an 80% ampacity correction factor when 4–6 current-carrying conductors are bundled together.
CEA NEC Code and Calculations 2
According to the NEC, what is the maximum voltage drop allowed for a branch circuit serving lighting loads?