Licensed Electrical Contractor Load Calculation and Services 3

Question 1

Per NEC 220.12, what is the general lighting load in VA per square foot for a bank?

Accepted Answer

3.5 VA/sq ft

Answer

NEC Table 220.12 lists banks at 3.5 VA per square foot for general lighting load calculations.

Question 2

How must the largest motor load be treated when included in a feeder or service calculation?

Accepted Answer

Add 25% of its full-load current to the total

Answer

NEC 220.50 and 430.24 require adding 25% of the largest motor's full-load current to feeder demand calculations.

Question 3

A 120/240V single-phase service supplies an electric dryer rated at 5,000 W. What load is used in the standard residential calculation?

Accepted Answer

The nameplate rating or 5,000 VA, whichever is larger

Answer

NEC 220.54 states the feeder demand for dryers is the nameplate rating or 5,000 VA, whichever is larger.

Question 4

What is the maximum number of service disconnecting means allowed for a single service?

Accepted Answer

6

Answer

NEC 230.71(A) limits the service disconnecting means to a maximum of six switches or circuit breakers.

Question 5

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)?

Accepted Answer

7,200 VA

Answer

2,400 sq ft × 3 VA/sq ft = 7,200 VA for general lighting and receptacle loads per NEC Table 220.12.

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