When is it appropriate to use the lesser of two loads in electrical calculations?

Using the lesser of two loads in electrical calculations is particularly relevant when you have two dwelling units supplied by a single feeder or service. This is in alignment with the National Electrical Code (NEC), which allows for the application of demand factors in certain scenarios.

When calculating the demand for multiple dwelling units, the NEC recognizes that not all units will draw their maximum load at the same time. Therefore, when two units are supplied by a single feeder, it's permissible to apply the demand factor, allowing the use of the lesser of the two calculated loads to determine the overall load on the feeder.

This practice helps electricians and engineers design systems that are more efficient and cost-effective by accurately estimating the load while ensuring safety and compliance with NEC requirements.