Load Calculation and Services 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 Load Calculation and Services flashcards as text
Per NEC 220.12, what is the general lighting load in VA per square foot for a bank?
Answer: 3.5 VA/sq ft
NEC Table 220.12 lists banks at 3.5 VA per square foot for general lighting load calculations.
How must the largest motor load be treated when included in a feeder or service calculation?
Answer: Add 25% of its full-load current to the total
NEC 220.50 and 430.24 require adding 25% of the largest motor's full-load current to feeder demand calculations.
A 120/240V single-phase service supplies an electric dryer rated at 5,000 W. What load is used in the standard residential calculation?
Answer: The nameplate rating or 5,000 VA, whichever is larger
NEC 220.54 states the feeder demand for dryers is the nameplate rating or 5,000 VA, whichever is larger.
What is the maximum number of service disconnecting means allowed for a single service?
Answer: 6
NEC 230.71(A) limits the service disconnecting means to a maximum of six switches or circuit breakers.
Under the standard calculation for a 2,400 sq ft dwelling, what is the general lighting and receptacle load before demand factors (using 3 VA/sq ft)?
Answer: 7,200 VA
2,400 sq ft × 3 VA/sq ft = 7,200 VA for general lighting and receptacle loads per NEC Table 220.12.
The demand factor for the first 3,000 VA of a residential lighting load is:
Answer: 100%
NEC Table 220.42 requires the first 3,000 VA of residential lighting load to be calculated at 100%.
When computing a service load for a multi-family dwelling with 20 units, what demand factor applies to the lighting load between 3,001 VA and 120,000 VA per NEC Table 220.42?
Answer: 35%
NEC Table 220.42 applies a 35% demand factor to the portion of dwelling lighting load between 3,001 VA and 120,000 VA.