Section 220.12/Lighting Load Calculations
NEC 220.12 and Table 220.12 establish minimum lighting load values per square foot by occupancy type, forming the basis for branch circuit and feeder sizing.
The general lighting load must be not less than the values in Table 220.12, which provides unit lighting loads in volt-amperes per square foot by occupancy type. Dwelling units require 3 VA per square foot. Office buildings require 3.5 VA per square foot. Warehouses require 0.25 VA per square foot. Hospitals require 2 VA per square foot. The floor area is computed from the outside dimensions of the building, not the usable area.
Why this section exists
The general lighting load establishes the minimum electrical capacity that must be provided regardless of the actual lighting fixtures specified. This prevents undersized electrical systems when fixtures are changed during the building's life. An office designed with efficient LED lighting today might be retrofitted with higher-wattage fixtures in the future. The Table 220.12 values represent a reasonable minimum that accommodates typical fixture changes.
What plan reviewers look for
Plan reviewers check the electrical load calculation for the general lighting load. They verify that the correct occupancy type from Table 220.12 is used, that the floor area is based on outside dimensions, and that the total VA matches or exceeds the table value times the area. They also check that the lighting load is included in the feeder and service calculations.
Common violations
Related NEC requirements
Section 210.11 covers the number of branch circuits required based on the calculated load. Section 215.2 covers feeder sizing. Section 220.14 covers receptacle outlet loads that are added to the general lighting load. Section 220.42 covers the demand factor reductions for lighting.