In residential installations, what is the minimum acceptable ampacity for a feeder line?

The minimum acceptable ampacity for a feeder line in residential installations is 100 amps. This specification is commonly derived from the National Electrical Code (NEC), which sets standards designed to ensure safety and reliability in electrical systems.

Choosing 100 amps as the minimum ensures that the feeder line can handle typical residential loads, which can include lighting, receptacles, and larger appliances. This level of ampacity also allows for the possibility of future expansion or additional circuits without the need for significant upgrades to the electrical system.

When evaluating other potential options, 50 amps may not provide sufficient capacity for modern residential electrical demands, and 75 amps generally does not accommodate the broad range of electrical needs as effectively. While 125 amps could support even higher loads or more extensive systems, it exceeds the minimum requirement and may not be necessary in all situations, especially in smaller homes. Therefore, 100 amps strikes a balance between safety, capacity, and future expandability, making it the correct choice in this context.