A trocar which automatically deactivates upon penetration through a body wall includes a housing portion, an obturator shaft mounted with respect to the housing portion and having proximal and distal ends, a conductor element extending at least partially along the obturator shaft for conducting energy from an energy source and a conductive tip member associated with the distal end of the obturator shaft for penetrating tissue. The conductive tip member is mounted for movement relative to the obturator shaft between a first position in communication with the conductor element and a second position disassociated from the conductor element.