Feed power in through one circuit back to the main board, on a different circuit cause a short, main breaker trips, main board is now isolated from the grid.
Technically possible, irresponsible, bad advice, and probably won’t work in most scenarios.
Technically possible, irresponsible, bad advice, and probably won’t work in most scenarios.
First the smaller circuits will trip first, that's where the current is actually flowing, there wouldn't be any actually flowing through the whole house breaker in your idea. The main circuit to your house is 100+ Amps (this would be a tiny old circuit most houses have larger main feeds these days) at least. You'd have to feed at that much through the main disconnect for it to trip.
Second even if you could push that many amps through the main breaker somehow to trip it you'd be feeding it through wires designed for 15-20 amp nominal loads which would cook them.
Well, you'd end up tripping the 15-20 amp breaker protecting those wires first.
The fault current that a breaker is required to be able to interrupt is two orders of magnitude larger than we're talking about feeding into the wire, and a 15 amp breaker is designed to _not_ interrupt a 150 amp load until a second has passed (there's a rating curve for this): some loads might require that much current briefly, and the wire in the wall is not going to overheat in that time (that's why the breaker has the curve that it does: to model and therefore protect the allowable heating of the wiring).
Doubly so because it doesn't even do what we want it to which would be to switch the main breaker off.