A high power electrical interface unit for a robotic tool changing system has a housing, a high power electrical connector in the housing for attachment to a high power electrical cable, and a replaceable high power electrical contact removably attachable to the electrical connector. The electrical contact extends into an opening in the housing and may be replaced through the opening without other disassembly of the interface unit. The contact may be threadably attachable to the connector, and the interface unit may include a member for preventing the electrical connector from rotating when the contact is threaded to the connector. The contact may include a head portion having a spheroidal or spherical contact surface, and a side surface configured for ready engagement by a hand tool such as a socket wrench. The interface unit may be removably secured to either a robot or tooling adaptor, or the interface unit may be integral to the robot or tool adaptor.