Licensed Electrical Contractor Licensed Electrical Contractor Load Calculation and Services Questions and Answers 2 — Questions and Answers
Question 1: When performing a standard load calculation for a single-family dwelling per NEC Article 220, what is the general lighting load allowance per square foot?
- 3 VA per square foot (Correct answer)
- 2 VA per square foot
- 5 VA per square foot
- 4 VA per square foot
Correct answer: 3 VA per square foot
The NEC specifies a general lighting load of 3 VA per square foot for dwelling units.
Question 2: What is the demand factor applied to the first 10 kVA of general lighting and receptacle loads in a dwelling unit calculation?
- 100% (Correct answer)
- 80%
- 75%
- 50%
Correct answer: 100%
The first 10 kVA of general lighting and receptacle loads is calculated at 100% demand factor per NEC Table 220.42.
Question 3: A 200-amp residential service uses a split-bus panel. How many main disconnect throws are permitted maximum?
- 6 (Correct answer)
- 4
- 2
- 8
Correct answer: 6
NEC 230.71 permits a maximum of six switches or circuit breakers to serve as the service disconnecting means.
Question 4: When calculating dryer load for a multifamily dwelling with 15 dryers, what demand factor applies per NEC Table 220.54?
- 47% (Correct answer)
- 100%
- 80%
- 35%
Correct answer: 47%
For 15 dryers, NEC Table 220.54 specifies a demand factor of 47%.
Question 5: What minimum service size does the NEC require for a single-family dwelling?
- 100 amperes (Correct answer)
- 60 amperes
- 150 amperes
- 200 amperes
Correct answer: 100 amperes
NEC 230.79(C) requires a minimum 100-ampere service for single-family dwellings.
Question 6: In a commercial load calculation, what demand factor is applied to the first 12.5 kVA of general lighting for an office building?
- 100% (Correct answer)
- 80%
- 50%
- 125%
Correct answer: 100%
NEC Table 220.42 requires the first 12.5 kVA of general lighting load to be calculated at 100% for commercial occupancies.
Licensed Electrical Contractor Licensed Electrical Contractor Load Calculation and Services Questions and Answers 2
When performing a standard load calculation for a single-family dwelling per NEC Article 220, what is the general lighting load allowance per square foot?