right ok, here goes, well as you hopefully know, I fitted a Hager Invicta 3 board in my house... See photo below for circuits to show what I mean.
What I am going to do is put everything on L1 that I would like to have UPS power, so basically if i put all the light circuits on L1 and maybe the alarm too, then the incomer at the bottom, remove the link to L1, so the Grid only feeds on to L2 and L3, that means there will be nothing on L1 ok.
So, what I then propose is to have an MCB on L2 in the board feed a wall mount UPS supply of say 3000VA and the load side of the UPS connect to L1 in the bottom of the main switch.
So basically all the light circuits are still independent of each other in terms of earth faults etc, but L1 is ok fed via the same supply, but all the circuits will be via the UPS, so in the event of power failure all L1 circuits will remain running.
No need for contactors or relays etc, this is much better and simpler, and if i was to switch off the main switch, everything will be dead. I see this to be the easiest, safest and most compliant option as the circuits will all be running via the UPS as if they were plugged in the back of it essentially.
as for the earth and neutral and earth, this is where I am not 100% sure, I can take the line from the load side of the UPS and connect it to L1, the earth, I suppose just connect it back on to the earth bar, and the neutral, I can't see it doing any harm putting it back on to the neutral bar?
I don't know though, does that sound ok with the neutral?
Reason for doing this is... Ok we hardly every get a power cut, but I want to be the one house in the street that has all its lights inside and out on like a beacon when the rest of the estate is in darkness!
Its not going to cost a great deal of money for a UPS as thats all I need as have everything else.
I would just need to move a couple of circuits around so that only lights were on L1.
