Summary
Highlights
A general use switch is rated in amperes and can interrupt its rated current at its rated voltage. These switches are commonly found in general distribution and branch circuits.
A general use snap switch is a common type of general use switch typically found in homes. These are covered in Article 404 of the NEC, which specifies ratings and installation requirements, such as allowing a 15-amp switch on a 20-amp circuit if the current does not exceed 15 amps.
Unlike general use switches, a motor circuit switch is rated in horsepower. This rating is crucial because it indicates the switch's ability to interrupt the maximum overload current of a motor with the same horsepower rating as the switch itself. If a switch lacks a horsepower rating, it is not a motor circuit switch.
A transfer switch is a device that transfers conductor connections from one power source to another, such as switching from utility power to a generator. Its primary purpose is safety, isolating the utility grid from backup power sources to prevent back-feeding, which can endanger utility workers. Transfer switches are required for emergency, legally required standby, and optional standby systems under Articles 700, 701, and 702 of the NEC.