What component is required for installation to indicate the presence of underground wiring?

The correct answer is the warning ribbon, which is an essential component used during the installation of underground wiring. This ribbon is typically placed above the buried wires and serves as a visual indicator for anyone who may be digging in the area. The presence of the warning ribbon helps prevent accidental damage to the wiring, which could lead to serious safety hazards or service interruptions. By alerting workers and the public to the presence of electrical lines, it significantly reduces the risk of injury and maintains the integrity of the electrical system.

In comparison, other components like the ground rod, conduit, and splice box have specific functions but do not serve the same warning purpose. A ground rod is primarily for grounding electrical systems, conduit is a protective tubing for wiring, and a splice box is used for connecting different wire segments. None of these components provide the necessary warning to indicate the presence of underground wiring, making the warning ribbon essential in such contexts.