US Patent 7288929 Inductive clamp for applying signal to buried utilities

An inductive clamp includes a pair of jaws configured to surround a conductor, and a pair of handles, each connected to a corresponding jaw. A pivotal connection is provided that allows the jaws to close around a conductor. The jaws are optionally biased to hold them closed around the conductor. A ferromagnetic core is mounted in each jaw and a coil surrounds at least one of the cores. An indicator is provided that tells a user that a signal has been applied to at least one of the cores.