What is the minimum ampacity requirement for the ungrounded service conductors in one-family houses?

The minimum ampacity requirement for the ungrounded service conductors in one-family houses is established to ensure that the electrical system can handle the typical load demands of a residence without overheating or becoming a safety hazard. A minimum of 100 amperes is required, as this rating supports a variety of household appliances, lighting, and other electrical needs that are common in a one-family residential setting.

This standard helps provide sufficient capacity for the electrical service to safely operate without tripping breakers or overloading circuits, which can lead to potential electrical fires and system failures. The National Electrical Code (NEC) reflects this requirement to promote safety and functionality in residential electrical systems. Lower ampacity ratings, such as 60 or 80 amperes, may be insufficient for modern homes, while 120 amperes is not commonly designated as a minimum for residential service. Therefore, 100 amperes serves as a balanced standard for residential buildings.