If you know the total lighting load that a feeder will supply, you don't necessarily need to size the feeder for that much load. In many cases, you can apply the lighting demand factors shown in Table 220.42. These demand factors attempt to reduce the calculated load on a given feeder to match the actual usage of the lighting branch circuits it supplies. Because not all lights are on at the same time, you don't need to size the feeder to supply them at the same time.
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