I think Mos has it right. One thing to consider if you're drilling. CALL DIG-ALERT FIRST. I wanted to bore some holes for getting water deep in the ground for some trees we planted. The guy for the electrical detection- our electric is underground- was late because a person was setting a post next to the house and hit the 220V coming in, and the tester was called in by first responders to verify exactly where the wires were. Fatality.