Branch Circuit Calculations Flashcards
7 cards from real Licensed Electrical Contractor practice questions. Tap to flip, then mark Knew It or Still Learning — missed cards come back until you master them.
Read the first 7 Branch Circuit Calculations flashcards as text
A 240V, single-phase branch circuit has a 30-ampere breaker. What is the maximum continuous load permitted on this circuit?
Answer: 24 amperes
For a continuous load, the maximum permitted is 80% of the breaker rating: 30A × 0.80 = 24 amperes.
Which NEC article specifically covers branch circuit requirements including ratings, outlet requirements, and conductor sizing?
Answer: Article 210
NEC Article 210 covers branch circuits, including their ratings, conductor requirements, and outlet placement.
A bathroom branch circuit in a dwelling supplies two GFCI receptacles. Per NEC 210.11(C)(3), what is the minimum circuit rating required?
Answer: 20 amperes
NEC 210.11(C)(3) requires at least one 20-ampere branch circuit for bathroom receptacle outlets.
When calculating branch circuit loads for general lighting in a store, what unit load in VA per square foot does the NEC Table 220.12 specify?
Answer: 3.3 VA/sq ft
NEC Table 220.12 assigns a unit load of 3.3 VA per square foot for store (retail) occupancies.
A branch circuit conductor has a calculated voltage drop of 4.8V on a 120V circuit. What is the percentage voltage drop?
Answer: 4%
Voltage drop % = (4.8V / 120V) × 100 = 4%, which exceeds the recommended 3% for branch circuits.
What is the maximum overcurrent device rating permitted for a branch circuit supplying only lighting outlets per NEC 210.23?
Answer: 20 amperes
NEC 210.23(A) permits lighting outlets on circuits rated up to 20 amperes when combined with cord-and-plug connected loads.
A 15-ampere, 120V branch circuit supplies receptacles in an office. Using the NEC demand factor for general-purpose receptacles, what load in VA is assigned to each receptacle?
Answer: 180 VA
NEC 220.14(I) assigns 180 VA per general-purpose receptacle outlet for load calculation purposes.