The invention provides for a method of multiplexing a plurality of intrinsically safe inputs for the purpose of functional redundancy using: a plurality of switching modules connected to an intrinsically safe output; and a plurality of substantially identical inputs from a plurality of intrinsically safe input sources to the plurality of respective switching modules; wherein a plurality of interlock signals between each of the switching modules are employed to permit a maximum of one of the switching modules to be active at any point in time, thereby permitting a maximum of one of the plurality of inputs from the plurality of input sources to be connected to the intrinsically safe output; and further including the step of providing a guaranteed minimum period where no input is connected to the intrinsically safe output during switching to an alternative switching module.
