How deep should underground service conductors that are not in concrete be buried to require a warning ribbon above it?

For underground service conductors that are not encased in concrete, the National Electrical Code (NEC) specifies that they must be buried at a minimum depth of 18 inches. When conductors are buried at this depth, a warning ribbon must be installed above them to alert anyone who may be digging in the area to the presence of the electrical lines below. This is essential for safety, helping prevent accidental damage to the conductors during excavation activities.

The requirement for a warning ribbon serves multiple purposes, including raising awareness of underground utilities and helping to prevent accidents. Burying conductors deeper than 18 inches is often required for other utilities, but for electrical service conductors specifically, 18 inches is the standard depth that triggers this need for additional caution through marking. This standard depth helps electricians and contractors know when they must alert those who may be working on or around the site, ensuring safe practices.