When an existing dryer or electric range is used, the NEC allows what regarding the grounded conductor of the existing branch circuit?

The correct choice highlights that when using an existing dryer or electric range circuit, the grounded conductor can be utilized to ground the appliance frame. This is aligned with the National Electrical Code (NEC) provisions that allow the continued use of existing circuits under specific conditions.

Historically, many older installations may have utilized a 3-wire system with a ground and neutral combined into one conductor. If the existing circuit is in compliance with current safety standards and is not a hazard, the grounded conductor can serve its purpose effectively. This means it can fulfill the requirement for grounding the appliance frame to help ensure safety by preventing electric shock in the event of a fault.

Utilizing the grounded conductor in this manner supports the principle of grounding by ensuring any stray voltage is directed safely away from users. It is important to note that any alterations needing to be made for compliance with the latest code should be performed to ensure safety, especially in modern contexts where separation of the ground and neutral is preferred in new installations.

In contrast, options that suggest the conductor cannot be used, must be replaced, or must be disconnected would not adhere to the NEC allowances in cases where the existing circuit is assessed as safe and compliant. Understanding the NEC's stance on the reuse of grounded conductors in