Abstract: A solid state motor starter assembly having controlled semiconductors mounted between heat sink members. Electrical power to the assembly can be connected an disconnected by an electrically operated solenoid that actuates a movable contact into engagement with a stationary contact mounted on the incoming heat sink. To reduce the heat generated in the semiconductor device during steady state full voltage operation, a shunting current path is established between the adjacent heat sinks by an electrically operated solenoid which moves a movable contact bar to engage stationary contact surfaces mounted directly on the heat sinks. Electrically joining the incoming line heat sink to the outgoing heat sink provides a low resistance parallel current path around the semiconductor thereby reducing the heat generated in the assembly during full voltage operation. The above contacts and solenoids can be directly mounted to a heat sink assembly thereby providing the benefits of unitized construction.