For a one-family dwelling, what is the minimum amperage rating for the service disconnecting means?

• A. 30 amps
• B. 60 amps
• C. 100 amps
• D. 150 amps

Answer: (C)

For a one-family dwelling, the main service disconnect must be able to carry the total service load that could be drawn. The code sets a practical minimum of 100 amperes for this disconnect, which covers typical dwelling needs—lighting, outlets, HVAC, water heating, and major appliances—without undersizing the service equipment. A 30- or 60-amp disconnect would be too small for normal dwelling loads and would trip or overload. A 150-amp disconnect is allowed, but it’s larger than necessary for the minimum requirement. So, the minimum rating that meets the standard for a single-family home is 100 amperes.