In electrical installations with several sub-distribution boards and residual current circuit breakers, an economical central ON-OFF control can be set up using the ISK 41 and ISK 42 switching devices developed for this purpose. The central control inputs are galvanically isolated from the inputs and outputs on the supply side by optocouplers. This means that, in contrast to conventional impulse switches with central control, ISK 41 and ISK 42 can also be connected between different networks, residual current circuit breakers or potentials without a decoupling relay. ISK 41: 1 NO contact 230V AC 16A, potential-free, dimensions: 18x55mm, 230V AC - 1S pf 16A