In article , "N_Cook"
wrote:

800 watt toroidal transformer operating at say 400 watts. Secondaries lead
to conventional bridge rectifier and smoothing caps for +/- rails. A break
appears in the DC rails central 0V return to the transformer, could that
lead to a blown mains fuse, via inductive action?

N_Cook-

It depends on the circuit. If the center tap opens, then voltage
between each side and ground will be determined by the ratio of each
side's resistance to ground. If one side's voltage gets so high that it
causes components to break down, resulting high current might blow the
mains fuse.

An open center tap might upset circuit balance so that everything is
turned on hard, resulting in too much current. On the other hand,
balanced resistances between each side and ground might not cause any
problem other than the circuit not working correctly.

Fred