When is a 120-volt cord-and-plug connected appliance allowed to have a two-wire cord?

A 120-volt cord-and-plug connected appliance is allowed to have a two-wire cord when the appliance is double insulated. Double insulation provides an extra layer of safety by isolating the electrical components from accessible parts of the appliance, ensuring that users are protected from shock hazards.

In appliances designed with double insulation, there is no need for a ground wire because the construction itself minimizes the risk of electrical shock. This design usually involves the use of materials that provide adequate insulation and eliminates the necessity for grounding, which is why a two-wire cord is permissible.

Other scenarios like having a faulty appliance, being permanently mounted, or using less than 10 amps do not inherently justify the use of a two-wire cord, as grounding safety remains essential regardless of the appliance's condition or power consumption.