Service and Load Calculations Flashcards

A 240-volt, 30-ampere clothes dryer circuit is installed in a dwelling. What minimum load must be used for service calculation per NEC 220.54?

Answer: 5,000 VA

NEC 220.54 requires each dryer to be calculated at 5,000 watts or the nameplate rating, whichever is larger.

In a standard residential load calculation, small appliance branch circuit loads are added at what VA per circuit?

Answer: 1,500 VA

NEC 220.52(A) requires 1,500 VA per 20-ampere small appliance branch circuit in the kitchen, dining, and pantry areas.

What is the NEC-required number of minimum small appliance branch circuits for a dwelling unit kitchen?

Answer: Two 20-ampere circuits

NEC 210.11(C)(1) requires at least two 20-ampere small appliance branch circuits for the kitchen, dining, and pantry areas.

When calculating the service load for four household clothes dryers in an apartment building, what demand factor does NEC Table 220.54 apply?

Answer: 80%

NEC Table 220.54 specifies an 80% demand factor when calculating the load for 4 clothes dryers.

Under the NEC optional method for dwelling units (220.82), what percentage is applied to the load above the initial 10 kVA?

Answer: 40%

NEC 220.82(B) applies 40% to all loads above the first 10 kVA when using the optional calculation method.

A 1,200 sq ft dwelling has two small appliance circuits and one laundry circuit. What is the total load before demand factors for these circuits plus general lighting?

Answer: 6,600 VA

Lighting: 1,200 × 3 = 3,600 VA; small appliances: 2 × 1,500 = 3,000 VA; total = 6,600 VA (laundry calculated separately under 220.52(B)).

For a commercial building, NEC Table 220.12 assigns what unit lighting load (VA/sq ft) for office occupancies?

Answer: 3.0 VA/sq ft

NEC Table 220.12 lists office occupancies at 3.5 VA/sq ft; however, many jurisdictions reference updated tables — the most common exam-tested value is 3.5 VA/sq ft.