What is the minimum allowable current rating for a three-wire service entrance conductor for a dwelling unit?

The minimum allowable current rating for a three-wire service entrance conductor for a dwelling unit is 100 amps. This requirement ensures that the electrical system can support the standard energy demands of residential living. A 100 amp service is typically sufficient for most single-family homes to power the general lighting, appliances, and other electrical loads commonly found in such residences.

Choosing a lower rating, such as 60 amps or 70 amps, would not adequately meet the needs for modern electrical appliances and systems, which can consume significant power. On the other hand, while a rating of 120 amps might be acceptable for larger homes or those with high electricity consumption, it exceeds the minimum requirement. Thus, 100 amps is established as the baseline standard for three-wire service entrances to ensure safety, efficiency, and compliance with the National Electrical Code (NEC) in many jurisdictions, including Rhode Island.