FI residual current circuit breaker, 4-pole, Type A, selective, In: 80 A, 300 mA, Un AC: 400 V. The residual current circuit breaker is the protective device for touch protection. Siemens' patented residual current protective devices are an essential component of the SENTRON protection systems for electrical installations, as they prevent life-threatening electrical accidents by safely disconnecting dangerous fault currents to the ground. Electrically ignited fires can be prevented right from their inception. Whether through direct contact with live parts or indirect contact with operating equipment, protection is primarily achieved through rapid disconnection. The Siemens FI circuit breakers 5SV are characterized by: 1. Comprehensive protection for people and property against electric shock. 2. Whether sinusoidal alternating fault currents or smooth direct fault currents - Siemens offers the appropriate type and special designs for all requirements. 3. Reliable safety.