Load Calculations Flashcards

When calculating the load for a residential kitchen small appliance branch circuits, the NEC requires a minimum of how many 20-ampere circuits?

Answer: Two 20A circuits

NEC 210.11(C)(1) requires at least two 20-ampere small appliance branch circuits for receptacle outlets in kitchen, pantry, breakfast room, and dining room.

For a 240V, single-phase motor rated at 10 HP, what is the full-load current used for conductor sizing per NEC Table 430.250?

Answer: 50A

NEC Table 430.250 lists 50A as the full-load current for a 10 HP, 240V, single-phase motor.

Under NEC Article 220, what demand factor applies to the first 3,000 VA of general lighting load in a dwelling unit?

Answer: 100%

NEC Table 220.42 applies 100% demand factor to the first 3,000 VA of lighting load in a dwelling.

A commercial building has 40 receptacle outlets in an office area. Using the NEC standard load calculation, what load in VA is assigned per receptacle?

Answer: 180 VA

NEC 220.14(I) assigns 180 VA per receptacle outlet for calculating branch circuit and feeder loads in commercial occupancies.

When calculating a feeder load for a dwelling with a 12 kW electric range, what demand value does NEC Table 220.55 allow for a single range?

Answer: 8,000 VA

NEC Table 220.55 Column C permits 8 kW (8,000 VA) demand for a single household range rated over 8¾ kW through 12 kW.

For optional feeder/service calculations in dwellings per NEC 220.82, the first 10 kVA of all other loads after air conditioning is applied at what demand factor?

Answer: 100%

NEC 220.82(B) applies 100% demand factor to the first 10 kVA of all other loads in the optional calculation method.

A 120/240V, single-phase service feeds a dwelling. The calculated load is 28,800 VA. What is the minimum service ampacity required?

Answer: 150A

28,800 VA ÷ 240V = 120A; the next standard service size per NEC 230.79 is 150A, and residential minimum is 100A—but 120A requires 150A service.