A cascaded fuel cell stack (9a) includes a plurality of groups (10-12) of fuel cells (13) connected electrically in series by means of conductive separator plates (58, 59) and current collecting pressure plates (56, 57). Each group has an inlet fuel distributing fuel inlet manifold (17a, 19c, 20c), a fuel exit manifold (19a, 20a) of each group except the last feeding the inlet manifold of each subsequent group. A microcontroller responds to signals from a plurality of voltage sensing devices (48a-48c) to cause corresponding switches (50a-50c) (a) to connect each group, and all preceding groups in the sequence, to a voltage limiting device (VLD) (45), or (b) to connect each group to its own (VLD (45a-45c), in response to sensing a predetermined average cell voltage across the corresponding group. When normal operation occurs, the microcontroller connects the main load and disconnects the voltage limiting device (53) (25).