It seems not everyone has current standard wiring and an up-to-date board with circuit breakers inside their unit. I get occasional requests 'out of hours' to let people into the switch room because a failed appliance has cut their power off completely. I am not an electrician, but it seems a good quality individual circuit breaker should deal with the problem inside the apartment; if they have to get to the main switchboard (which I regard as a backup and a last resort), then they probably have a problem with the individual unit's wiring, which needs urgent attention beyond resetting the circuit breaker on the main switchboard. Perhaps a FlatChatter who is an electrician can comment – and put me right if necessary.