What is the typical amperage rating for branch circuits in residential wiring?

The typical amperage rating for branch circuits in residential wiring is indeed 15 or 20 amperes. This standard is based on the National Electrical Code (NEC) guidelines, which specify these ratings for most general-purpose circuits used in homes. For example, 15-amp circuits are commonly used for outlets in living areas, while 20-amp circuits are typically used for kitchens and bathrooms where higher loads may be present, such as appliances.

Using this amperage ensures safety and compliance with electrical standards, allowing for adequate power distribution without risking overheating or electrical fires. Circuits rated lower than 15 amperes might not provide sufficient capacity for modern household needs, while those rated higher than 20 amperes can be reserved for specific applications and should comply with additional code requirements.