In electrical installations with multiple sub-distributions and residual current circuit breakers, an economical central on-off control can be established using the specially designed devices ISK 41 and ISK 42. The central control inputs are galvanically isolated from the supply side inputs and can be operated with voltages ranging from 8-230V AC or DC. The ISK 42 additionally features a second potential-free relay contact (10A normally open) and a central pulse input. Dimensions: 18x55mm, 230V AC - 2S pf 16/10A.