Electrician's Licensing Practice Exam

A subpanel does not require a bonding screw due to the nature of its installation and function within an electrical system. The National Electrical Code (NEC) specifies that bonding screws should only be used in the main service panel, where the grounding and neutral connections must be bonded together. In a subpanel, the grounding and neutral conductors must remain separate to prevent unwanted current flow on the grounding system and maintain safety in the electrical installation. This separation is critical for reducing the risk of electric shock and ensuring that any faults are detected by the electrical system's protective devices.

In specific installations such as subpanels in residential settings, the requirement is to have separate grounding and neutral bars, which aligns with the NEC's intent to keep these systems isolated at subpanels. As a result, a bonding screw is unnecessary and inappropriate in subpanels, reaffirming that the answer correctly identifies this aspect of NEC regulations.