Appliance Wiring: Disconnecting Means and Overcurrent Protection

Portable appliances: The plug-and-receptacle arrangement is all that is required. The plug and receptacle must have a rating in amperes and volts at least as great as that of the appliance.

Small permanently connected appliances: If the appliance is rated at 300 watts or less (1/8 hp or less), the branch circuit overcurrent protection is sufficient. No special disconnecting means is required. Range hood fans and bathroom exhaust fans are examples of small permanently connected appliances.

Large appliances, not motor-driven: Wall-mounted electric heaters and ceiling-mounted heat lamps are examples in this category. If the appliance is connected to a circuit also serving other loads and if the circuit is protected by circuit breaker, or by fuses mounted on a pullout block, no special action is needed. If the circuit is protected by plug fuses, you must install, for each appliance, a separate switch of the general type shown in diagram below. The switch need not be fused, but unfused switches are hard to find, so it’s customary to use the fused kind, with one fuse for 120-volt appliances and two fuses for 240-volt appliances. A circuit breaker may be used instead. Of course, don’t install a fuse or breaker in the grounded (white) wire.

Large motor-driven appliances: For motors that are not automatically started (dishwashers, waste disposers, etc.), proceed as if the appliance were not motor driven (see previous paragraph). But if the motor is automatically started, such as a water pump or an air conditioner, then provide built-in or separate motor over load protection rated at not over 125 percent of the ampere rating of the motor to protect the motor against overload or failure to start. While not required by the NEC, it’s wise to provide an individual circuit for each automatically started motor.