A re-usable ultrasonic medical device comprising: a handle assembly; an elongated shaft assembly, mechanically coupled to the handle assembly, having an interior distal portion over-molded with an electrically insulating material, wherein at least a portion of a proximal interior surface of the elongated shaft assembly is electrically conducting; a second electrical contact electrically coupled to the electrically conducting interior surface of the elongated shaft assembly; an electrically conducting waveguide disposed within the elongated shaft assembly; a first electrical contact electrically coupled to the electrically conducting waveguide; an electrically conducting ultrasonic knife acoustically and electrically coupled to the waveguide, having a distal portion coated with an electrically insulating coating; a generator configured to deliver power to an ultrasonic transducer acoustically coupled to the waveguide; and a controller module configured to control the generator, wherein the controller module comprises: a processor; and a memory circuit configured to contain instructions which, when executed by the processor, causes the processor to: apply an electrical potential between the first contact and the second contact; measure an electrical current flowing between the first contact and the second contact; and notify a user of the re-usable ultrasonic medical device when the electrical current has a value outside a tolerance range. a handle assembly; an elongated shaft assembly, mechanically coupled to the handle assembly, having an interior distal portion over-molded with an electrically insulating material, wherein at least a portion of a proximal interior surface of the elongated shaft assembly is electrically conducting; a second electrical contact electrically coupled to the electrically conducting interior surface of the elongated shaft assembly; an electrically conducting waveguide disposed within the elongated shaft assembly; a first electrical contact electrically coupled to the electrically conducting waveguide; an electrically conducting ultrasonic knife acoustically and electrically coupled to the waveguide, having a distal portion coated with an electrically insulating coating; a generator configured to deliver power to an ultrasonic transducer acoustically coupled to the waveguide; and a controller module configured to control the generator, wherein the controller module comprises: a processor; and a memory circuit configured to contain instructions which, when executed by the processor, causes the processor to: apply an electrical potential between the first contact and the second contact; measure an electrical current flowing between the first contact and the second contact; and notify a user of the re-usable ultrasonic medical device when the electrical current has a value outside a tolerance range. a processor; and a memory circuit configured to contain instructions which, when executed by the processor, causes the processor to: apply an electrical potential between the first contact and the second contact; measure an electrical current flowing between the first contact and the second contact; and notify a user of the re-usable ultrasonic medical device when the electrical current has a value outside a tolerance range. apply an electrical potential between the first contact and the second contact; measure an electrical current flowing between the first contact and the second contact; and notify a user of the re-usable ultrasonic medical device when the electrical current has a value outside a tolerance range.