An ultrasonic surgical instrument and method of assembly with a predetermined alignment includes first and second modular assemblies and an electrical lockout. The first modular assembly includes at least a portion of an end effector configured to manipulate a tissue. The second modular assembly includes a transducer power circuit and an activation switch electrically connected to the transducer power circuit. The electrical lockout is electrically connected to the transducer power circuit and configured to inhibit the activation switch from powering the ultrasonic transducer with the first and second modular assemblies misaligned from the predetermined alignment such that the first and second modular assemblies are in a locked-out state. The electrical lockout is further configured to allow the activation switch to power the ultrasonic transducer with the first and second modular assemblies in the predetermined alignment such that the first and second modular assemblies are in an operational state.
