Which components are exempt from being listed due to their non-impact on system performance?

The correct choice is drain piping and drain valves, which are viewed as components that do not significantly influence the operational effectiveness of a sprinkler system. These items are designed mainly to handle the collection and removal of water that may accumulate in the system, rather than being integral to the system's primary function of fire suppression. Their role is more about convenience and maintenance rather than being critical components that directly impact the performance of the fire protection system.

In contrast, sprinkler heads, fire department connections, and water supply lines are essential elements of a sprinkler system. Sprinkler heads are responsible for discharging water to suppress fires, the fire department connection allows external firefighting resources to connect to the system, and water supply lines are vital for delivering the necessary water to the system during operation. Because of their essential roles, these components must be listed and compliant to ensure effective fire protection. Thus, drain piping and drain valves can be exempt from the listing requirement as they do not affect the fundamental firefighting capabilities of the sprinkler system.