Before you starting digging in your yard, no matter how trivial you think it is (planting a tree, digging holes for fence posts, putting in a deck, installing sprinklers, or putting in a low-voltage lighting system), you should always call 811 first. 811 is a relatively new number/service that will help you to find the location of buried utilities on your property. Not knowing the location of these utilities before you dig can lead to inconvenient problems such as death.