Licensed Electrical Contractor Branch Circuit Calculations Questions and Answers Flashcards
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Read the first 6 Licensed Electrical Contractor Branch Circuit Calculations Questions and Answers flashcards as text
A 120V branch circuit supplies a 1,500W electric water heater. What is the minimum circuit ampere rating required per NEC Article 422?
Answer: 20 amperes
A 1,500W load at 120V draws 12.5A, and since a fixed appliance requires 125% sizing, the minimum is 15.625A, requiring a 20A circuit.
What is the maximum number of 180VA receptacle outlets permitted on a 20-ampere, 120-volt general-purpose branch circuit?
Answer: 13
A 20A circuit at 120V provides 2,400VA, and dividing by 180VA per outlet yields a maximum of 13 receptacle outlets.
When calculating branch circuit loads for a commercial kitchen, a 5,000W electric oven connected to a 240V single-phase circuit draws how many amperes?
Answer: 20.83 amperes
Dividing 5,000W by 240V yields approximately 20.83 amperes of current draw.
Per NEC 210.11(C)(3), a dwelling unit requires at least how many 20-ampere small-appliance branch circuits for the kitchen and dining areas?
Answer: 2
The NEC requires a minimum of two 20-ampere small-appliance branch circuits serving kitchen countertop and dining area receptacles.
A 14 AWG copper conductor on a 15-ampere branch circuit can safely supply a maximum continuous load of how many amperes?
Answer: 12 amperes
A continuous load on a 15A branch circuit is limited to 80% of the rating, which equals 12 amperes.
For a multiwire branch circuit supplying line-to-neutral loads, the neutral conductor carries the unbalanced current. If Line A draws 12A and Line B draws 8A, what current flows on the neutral?
Answer: 4 amperes
On a multiwire branch circuit, the neutral carries only the difference between the two line currents, which is 12A minus 8A equaling 4A.