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 hotel room branch circuit supplies only receptacles. The NEC allows a demand factor for hotel receptacle loads above a certain threshold. What is the demand factor applied to hotel guest room receptacle loads exceeding the first 10 kVA?
Answer: 50%
NEC Table 220.42 allows a 50% demand factor for hotel guest room receptacle loads above the first 10 kVA.
What is the maximum rating of an individual branch circuit that can serve a single receptacle outlet per NEC 210.21(B)(1)?
Answer: The receptacle rating must equal the branch circuit rating
NEC 210.21(B)(1) states a single receptacle on an individual branch circuit must have an ampere rating equal to the branch circuit rating.
A branch circuit in a school classroom is calculated at 3.5 VA per square foot for a 900 sq ft room. What is the total branch circuit load in VA?
Answer: 3,150 VA
Total load = 3.5 VA/sq ft × 900 sq ft = 3,150 VA for the classroom branch circuit load.
Which of the following best describes a multiwire branch circuit as defined in NEC Article 100?
Answer: A circuit with two or more ungrounded conductors sharing a common neutral, with voltage between ungrounded conductors
A multiwire branch circuit has two or more ungrounded conductors sharing a common neutral, with line-to-line voltage between the hot conductors.
A 120/240V, 3-wire multiwire branch circuit must have its ungrounded conductors disconnected simultaneously per NEC 210.4(B). Which device accomplishes this?
Answer: A 2-pole breaker or handle-tied single-pole breakers
NEC 210.4(B) requires a means to simultaneously open all ungrounded conductors, accomplished by a 2-pole breaker or handle-tied single-pole breakers on opposite phases.
For general lighting branch circuit load calculations in a dwelling unit, NEC Table 220.12 specifies what unit load per square foot?
Answer: 3 VA per square foot
NEC Table 220.12 assigns a unit load of 3 VA per square foot for dwelling units for general lighting and receptacle calculations.
A 20-ampere branch circuit at 120V supplies show window lighting in a store. Per NEC 220.14(F), what minimum load must be included per linear foot of show window?
Answer: 200 VA per linear foot
NEC 220.14(F) requires a minimum load of 200 VA per linear foot for show window lighting in commercial occupancies.