Licensed Electrical Contractor Licensed Electrical Contractor Load Calculation and Services Questions and Answers 2

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?

Accepted Answer

3 VA per square foot

Answer

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?

Accepted Answer

100%

Answer

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?

Accepted Answer

6

Answer

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?

Accepted Answer

47%

Answer

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?

Accepted Answer

100 amperes

Answer

NEC 230.79(C) requires a minimum 100-ampere service for single-family dwellings.

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Licensed Electrical Contractor Licensed Electrical Contractor Load Calculation and Services Questions and Answers 2