How many 20-amp 120V lighting branch circuits are required for a 5,500 square-foot retail store?

How many 20-amp 120V lighting branch circuits are required for a 5,500 square-foot retail store?

• A. 4
• B. 3
• C. 5
• D. 6

Answer: (C)

General lighting-load sizing for mercantile (retail) spaces uses a watts-per-square-foot method. For this type of space, a common value is 2 VA (or 2 watts) per square foot for the general lighting load. Compute the total load: 5,500 ft² × 2 VA/ft² = 11,000 VA. A single 20-amp, 120-volt circuit can supply up to 20 A × 120 V = 2,400 VA. To determine how many circuits are needed, divide the total load by the circuit capacity: 11,000 ÷ 2,400 ≈ 4.58. Since you can’t have a fraction of a circuit, you round up to 5 circuits. Five circuits provide a capacity of 12,000 VA, which meets and exceeds the 11,000 VA load. If the lighting load were heavier or a higher watts-per-square-foot value were used, more circuits would be required.

General lighting-load sizing for mercantile (retail) spaces uses a watts-per-square-foot method. For this type of space, a common value is 2 VA (or 2 watts) per square foot for the general lighting load.

Compute the total load: 5,500 ft² × 2 VA/ft² = 11,000 VA.

A single 20-amp, 120-volt circuit can supply up to 20 A × 120 V = 2,400 VA. To determine how many circuits are needed, divide the total load by the circuit capacity: 11,000 ÷ 2,400 ≈ 4.58. Since you can’t have a fraction of a circuit, you round up to 5 circuits.

Five circuits provide a capacity of 12,000 VA, which meets and exceeds the 11,000 VA load. If the lighting load were heavier or a higher watts-per-square-foot value were used, more circuits would be required.