Licensed Electrical Contractor FREE Licensed Electrical Contractor Services, Feeders, and Branch Circuits Questions and Answers 2 — Questions and Answers
Question 1: According to the NEC, what is the minimum size conductor permitted for a 200-amp residential service entrance?
- 2/0 AWG copper
- 3/0 AWG copper (Correct answer)
- 4/0 AWG copper
- 250 kcmil copper
Correct answer: 3/0 AWG copper
Per NEC Table 310.12, a 200-amp service requires a minimum of 3/0 AWG copper or 4/0 AWG aluminum conductors.
Question 2: What is the maximum number of overcurrent devices permitted on a single panelboard in accordance with NEC Article 408?
- 30
- 42 (Correct answer)
- 48
- No limit specified
Correct answer: 42
NEC 408.54 limits a panelboard to a maximum of 42 overcurrent devices (excluding the main breaker).
Question 3: When calculating feeder demand load for a commercial kitchen, what demand factor applies to the first 12 kW of commercial electric cooking equipment per NEC Table 220.56?
- 65% (Correct answer)
- 75%
- 80%
- 100%
Correct answer: 65%
NEC Table 220.56 permits a 65% demand factor for commercial electric cooking equipment rated over 12 kW.
Question 4: A multiwire branch circuit supplying line-to-neutral loads must be disconnected simultaneously by which means?
- Individual single-pole breakers
- A multipole breaker or handle ties (Correct answer)
- A separate disconnect switch only
- Any listed overcurrent device
Correct answer: A multipole breaker or handle ties
NEC 210.4(B) requires multiwire branch circuits to be disconnected simultaneously using multipole breakers or approved handle ties.
Question 5: What is the maximum continuous load permitted on a branch circuit breaker rated at 30 amperes?
- 20 amperes
- 24 amperes (Correct answer)
- 27 amperes
- 30 amperes
Correct answer: 24 amperes
Continuous loads are limited to 80% of the overcurrent device rating, so 30A × 0.80 = 24 amperes.
Question 6: Per NEC 215.2(A)(1), feeder conductors must have an ampacity not less than required to supply the load as calculated in which parts of Article 220?
- Parts I and II only
- Parts III, IV, and V
- Parts I through V (Correct answer)
- Parts II and III only
Correct answer: Parts I through V
NEC 215.2(A)(1) requires feeder conductors to have ampacity sufficient for loads calculated per Parts I through V of Article 220.
Licensed Electrical Contractor FREE Licensed Electrical Contractor Services, Feeders, and Branch Circuits Questions and Answers 2
According to the NEC, what is the minimum size conductor permitted for a 200-amp residential service entrance?