Licensed Electrical Contractor Load Calculation and Services 4

Question 1

Under NEC 230.42, the service entrance conductors must have an ampacity not less than the load calculated per Part III of Article 220, but never less than:

Accepted Answer

The calculated load only

Answer

NEC 230.42(A) requires ampacity not less than the calculated load; the 100A minimum is a service rating rule under 230.79, not a conductor rule.

Question 2

A commercial load includes 150 kVA of show window lighting. Per NEC 220.14(G), what unit load is used for show window lighting?

Accepted Answer

200 VA per linear foot

Answer

NEC 220.14(G) requires show window lighting to be calculated at a minimum of 200 VA per linear foot of show window.

Question 3

What is the calculated load for two 6 kW household ranges using NEC Table 220.55, Column C?

Accepted Answer

11 kW

Answer

NEC Table 220.55 Column C lists the demand for two ranges rated up to 12 kW each as 11 kW.

Question 4

For a 480/277V, 3-phase, 4-wire commercial service, what is the VA calculation for a balanced lighting load of 300A per phase?

Accepted Answer

207,846 VA

Answer

VA = √3 × 480V × 300A ≈ 249,415 VA; for per-phase balanced load on a 277V branch: 277V × 300A × 3 = 249,300 VA — closest answer is 249,415 VA.

Question 5

Per NEC 220.60, when calculating feeder or service loads, which of the following is a noncoincident load?

Accepted Answer

Electric heating and air conditioning loads

Answer

NEC 220.60 permits using only the larger of noncoincident loads—such as heating and cooling—since both are unlikely to operate simultaneously.

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Licensed Electrical Contractor Practice Test

Licensed Electrical Contractor Load Calculation and Services 4