Whenever you are preparing to do any digging in your yard you should always call to have utility lines marked. When beginning my lawn work I called my local utility and set up an appointment to have my lines marked. The call was simple and I was able to make an appointment for the next day. It's a free service which can save you hassle and serious injury.
When my lines were marked I found that my electrical service goes all the way around the back of the house to get to the panel. If I had only been working in the backyard I might not have had the lines marked, and this would have lead to trouble. Even if you think you know where your utilities are buried, stay safe and dial 811 before digging.
Practice Smart Digging.