When sizing office building lighting, you must use the larger of which two values?

When sizing office building lighting, you must use the larger of which two values?

• A. The larger of 1.3 VA/SF or the actual connected load
• B. 1.0 VA/SF or the actual connected load
• C. 1.3 VA/SF only
• D. The actual connected load only

Answer: (A)

When sizing office building lighting, you compare two potential loads and take the larger one to size the feeders and service. One value comes from a standard allowance based on area: 1.3 VA per square foot for office spaces. The other value is the actual connected load—the sum of the VA ratings of all the installed lighting equipment. The reason for choosing the bigger of the two is to ensure the system is sized to handle real, installed conditions and to prevent under-sizing in cases where the actual lighting load exceeds the standard per-square-foot estimate. For example, if you have 2,000 square feet, the area-based load is 2,000 × 1.3 = 2,600 VA. If the actual connected lighting adds up to 3,000 VA, you would size to 3,000 VA. If the actual connected load is only 2,000 VA, you still size to 2,600 VA because that’s larger. Using only the per-square-foot value or only the actual connected load can lead to under- or over-sizing; the required approach is to use the larger of the two to ensure adequate capacity.

When sizing office building lighting, you compare two potential loads and take the larger one to size the feeders and service. One value comes from a standard allowance based on area: 1.3 VA per square foot for office spaces. The other value is the actual connected load—the sum of the VA ratings of all the installed lighting equipment. The reason for choosing the bigger of the two is to ensure the system is sized to handle real, installed conditions and to prevent under-sizing in cases where the actual lighting load exceeds the standard per-square-foot estimate.

For example, if you have 2,000 square feet, the area-based load is 2,000 × 1.3 = 2,600 VA. If the actual connected lighting adds up to 3,000 VA, you would size to 3,000 VA. If the actual connected load is only 2,000 VA, you still size to 2,600 VA because that’s larger.

Using only the per-square-foot value or only the actual connected load can lead to under- or over-sizing; the required approach is to use the larger of the two to ensure adequate capacity.