What color code is used by utility locators to indicate an underground gas line?

The color code used by utility locators to indicate an underground gas line is yellow. In the national system of color coding for underground utilities, yellow is specifically designated for gas, petroleum, or other flammable materials. This color helps to ensure that individuals working on or near the ground are aware of the potential hazards associated with underground gas lines, thus promoting safety and reducing the risk of accidental damage during excavation or construction work.

In the context of the other colors, red is used for electric power lines, green for sewer and drain lines, and blue for potable water. Each color serves a distinct purpose in utility identification, which is critical for preventing accidents and ensuring proper handling of various types of utility infrastructure.