In General Power Lines Depth.
There are several key factors to consider when determining the possible presence, depth and protection of underground power lines. Luckily, all fifty states provide a toll free hotline that will connect you to professional utility location services that will come and locate any underground power lines for free. Requirements for buried power lines can differ geographically. Although the National Electric Code provides minimum specifications for underground low voltage electrical circuits, the physical characteristics of the installation will determine the actual depth.
Direct Burial Installation
There are two common methods of installing underground power lines. The direct burial method is the placement of a multi-conductor cable with a jacket that is manufactured to resist the elements of corrosion associated with soil and moisture. The minimum depth requirement of a direct burial cable is 24 inches, except when installed under a concrete slab with a minimum thickness of 2 inches. In this case, the cable can be installed at only 18 inches deep.
Installing in a Raceway
Another option is to install an underground raceway, also known as a conduit to house separate individual conductors. When installing a non-metallic underground raceway, the minimum burial depth is 18 inches, except when installed under a concrete slab with a minimum thickness of 2 inches, in which case the conduit can be installed at only 12 inches deep. When installing an underground metallic raceway, the minimum burial depth is a mere 6 inches.
Call Before You Dig
If you are considering an excavation of any depth, don't gamble with your safety. Even small jobs like planting a shrub or tree on your property requires that you call 811 before you start digging. Failure to do so can result in damage to underground systems, heavy fines, repair costs and serious injury or death.