Load Calculations Flashcards

For a commercial occupancy, NEC 220.14(K) allows show window lighting to be calculated at what VA per linear foot as an alternative to actual load?

Answer: 200 VA/ft

NEC 220.14(K) permits show window lighting to be calculated at 200 VA per linear foot of show window as an alternative calculation method.

When sizing a service for a school building with 50,000 sq ft, what VA per sq ft does NEC Table 220.12 specify for general lighting?

Answer: 1.5 VA/sq ft

NEC Table 220.12 assigns 1.5 VA per square foot as the unit load for schools.

A 208V, 3-phase panel supplies a 30 kW balanced resistive load. What is the line current?

Answer: 72.2A

I = kW × 1000 ÷ (√3 × V) = 30,000 ÷ (1.732 × 208) ≈ 83.3A for a balanced 3-phase resistive load.

Per NEC 220.83, what percentage of heating and cooling load is used in the optional calculation for existing dwelling service upgrades when both cannot operate simultaneously?

Answer: 100% of larger, 0% of smaller

NEC 220.83 uses only the larger of the heating or cooling load (noncoincident loads per 220.60) for existing dwelling optional calculations.

What is the minimum calculated load for a 1,500 sq ft dwelling's general lighting before demand factors per NEC Table 220.12?

Answer: 4,500 VA

1,500 sq ft × 3 VA/sq ft = 4,500 VA per NEC Table 220.12 for dwelling occupancies before any demand factors.

Under NEC 230.42, when a service entrance conductor carries a continuous load, it must be sized at a minimum of what percentage of the continuous load?

Answer: 125%

NEC 230.42(A) requires service entrance conductors to have an ampacity of at least 125% of the continuous load plus 100% of non-continuous loads.

A warehouse with 80,000 sq ft requires a lighting load calculation. Using NEC Table 220.12, what unit load applies to warehouses?

Answer: 0.25 VA/sq ft

NEC Table 220.12 assigns 0.25 VA per square foot as the unit load for warehouses (storage).