Licensed Electrical Contractor FREE Licensed Electrical Contractor Services, Feeders, and Branch Circuits Questions and Answers 2

Question 1

According to the NEC, what is the minimum size conductor permitted for a 200-amp residential service entrance?

Accepted Answer

3/0 AWG copper

Answer

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?

Accepted Answer

42

Answer

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?

Accepted Answer

65%

Answer

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?

Accepted Answer

A multipole breaker or handle ties

Answer

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?

Accepted Answer

24 amperes

Answer

Continuous loads are limited to 80% of the overcurrent device rating, so 30A × 0.80 = 24 amperes.

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Licensed Electrical Contractor FREE Licensed Electrical Contractor Services, Feeders, and Branch Circuits Questions and Answers 2