What type of assembly is explicitly mentioned as not needing to be bonded in hydromassage bathtubs?

In the context of hydromassage bathtubs, the National Electrical Code (NEC) specifies that certain components do not require bonding to the grounding system to ensure safety from electrical shock hazards. The correct answer indicates that supply valve assemblies are among those specifically mentioned as exempt from bonding requirements.

This exemption is based on the understanding that supply valves typically do not present a surface that can become energized or offer a pathway to ground that would increase the risk of electric shock in the event of a fault condition. The NEC provides these specifications to intelligently reduce installation complexity while promoting safety, ensuring that unnecessary bonding does not impede the function of the bathtub or interfere with plumbing connections.

Other types of assemblies, such as plastic drain assemblies, corroded metallic piping, and service equipment assemblies, may have different bonding requirements or conditions that necessitate bonding to mitigate the risks associated with electrical potential. By clarifying that supply valve assemblies do not need to be bonded, the code streamlines compliance for both manufacturers and installers, ensuring that they focus resources on areas where electrical safety is a greater concern.