Licensed Electrical Contractor Load Calculation and Services Questions and Answers

Question 1

An electrical contractor is calculating the service size for a 2,500 sq. ft. single-family dwelling using the standard method.
The calculation includes the general lighting load, two 20-amp small appliance circuits, and one 20-amp laundry circuit.
According to NEC Article 220, what is the demand load for these specific components before considering any other loads like fixed appliances or HVAC?

Accepted Answer

5,550 VA

Answer

12,000 VA

Answer

10,500 VA

Answer

4,500 VA

Question 2

When calculating the ampacity for a feeder supplying several motors, which of the following calculations is required by NEC 430.24?

Accepted Answer

125% of the FLC of the highest-rated motor plus the sum of the FLCs of all other motors.

Answer

100% of the full-load current (FLC) of all motors combined.

Answer

125% of the FLC of the smallest motor plus 100% of the FLC of all other motors.

Answer

125% of the sum of the FLC of all motors on the feeder.

Question 3

A contractor is using the optional method under NEC 220.84 to calculate the service load for a new 10-unit apartment building. Which of the following loads must be calculated separately under Article 220, Part III, and added to the result from Table 220.84?

Accepted Answer

The house loads, such as hallway lighting and a common laundry facility.

Answer

The individual dwelling unit cooking appliance loads.

Answer

The general lighting load for each apartment.

Answer

The small-appliance circuit loads for each dwelling unit.

Question 4

According to NEC Table 220.56, demand factors for commercial kitchen equipment shall not be applied to which of the following?

Accepted Answer

Ventilating equipment

Answer

Dishwasher booster heaters

Answer

Deep fat fryers

Answer

Convection ovens

Question 5

An electrical contractor is calculating the general lighting and receptacle load for a 40,000 sq. ft. retail store. Using the unit load values from NEC Table 220.12 and the demand factors from Table 220.42, what is the calculated load?

Accepted Answer

85,000 VA

Answer

120,000 VA

Answer

60,000 VA

Answer

100,000 VA

Question 6

When performing a load calculation for a single-family dwelling, which four types of loads are specifically excluded from the 75% demand factor allowed for four or more fastened-in-place appliances under NEC 220.53?

Accepted Answer

Space-heating equipment, clothes dryers, cooking equipment, and air-conditioning equipment.

Answer

Dishwasher, garbage disposal, trash compactor, and water heater.

Answer

Well pump, attic fan, garage door opener, and central vacuum system.

Answer

Water heater, dishwasher, range hood, and microwave oven.