Manual standby generator

Where we live the ESB power is not as reliable as I would like.
5+ outages in the past year, average time out 3-4 hours.

I am considering the idea of buying a petrol standalone generator (manual start/stop), and having an automatic switch over unit that when mains fails disconnect part of the house wiring from the mains feed and provide a direct connection from the generator to the fridge, freezer and part of the lighting circuit.
For safety it will NEVER connect the generator directly to the grid.
Are there any suitable control units that do this?

Hoagy

The ETCI Wiring Rules stipulate that the entire installation must be disconnected from the incoming mains before a generator can be connected to any part of the installation.
So the first thing you will need is a changeover switch on the supply to your cinsumer unit, changing it over entirely from ESB to generator.
To do what you then want automatically will mean splitting the circuits on your consumer unit into essential and non-essential circuits and then some arrangement of contactors to only feed the essential circuits.
It would probably be easier to do that manually since you have to do the changeover and start the generator by hand anyway.
You will also need some means of identfying when the ESB returns.

Yes, I was comptemplating the idea of having a split or two CU's one for essential supply and the other for everything else.

The essential supply unit being fed from the other CU via a change over switch in the garage, would that type of setup be acceptable.

Hoagy

Once your c/o switch isolates the ESB supply entirely it's ok.