Backup Generator connection

[John Noble]

At our previous house we had a small generator used successfully during power cuts to power the essentials - fridge, heating, some lights, tv. We just plugged the generator output into a socket in the kitchen.
Our present house has a 3 phase supply to 2 consumer units. One has a few non-essential connections -sauna, steam shower, spa bath pump and will be left unpowered during mains failures. The other powers the rest of the house - including the garage with an 11kw car charger using all 3 phases. This would be tripped out if using the generator and the rest of the loads restricted to less than the 3kw rating of the generator.
During the couple of power cuts so far, I have just connected a lead from the generator to a socket in the kitchen to power the fridge freezer etc and some lights and sockets in the rest of the house on that phase with no problems.
Clearly that is not very satisfactory so we have just installed a 3 phase changeover switch to the essentials consumer unit with a couple of outdoor sockets by the back door a few feet away from the changeover switch. The generator sockets are both earthed to main earth pin outside the back door The generator would be just outside the door with 5ft cables from its 2 outputs into the 2 sockets. All 3 phases would be powered from the generator which should work with the car charger tripped and suitable load restriction.
RCDs are fitted to the 2 cables between the changeover switch and the generator supply. One cable is connected to one phase and the other to the other two. This is not really necessary as the 2 sockets on the generator are wired in parallel but at least either output CB can operate independently. At present alas any attempt to connect the generator trips the RCDs.
The generator is an inverter type where I understand both live and neutral outputs are 115 v to earth, giving the desired 230v between them.
I do not think the RCDs are essential but are confused by the inverter generator output. So is the answer to remove them?
Any advice would be most welcome.

 

[poni]

We just plugged the generator output into a socket in the kitchen.

5ft cables from its 2 outputs into the 2 sockets

I do not think the RCDs are essential

close the door and walk away slowly

 

[poni]

One cable is connected to one phase and the other to the other two

3 phases

????

 

[kerching]

To prevent an unwanted visit from Trumpton and even possibly half an hour out with a Vicar/Celebrant I advise getting in an electrician that knows about generators and C/O or ATS Control

 

[binky]

is the generator a 3 phase unit?

Can you post a picture ofthe board supplying essentials, and the other boards ideally showing the MCB labels.

To be frank your electrical system doesn't sound too clever. Either way, I would connect via a commando socket, 16A or higher depending on the genie. output.

 

[nicebutdim]

Realistically the most important reference here should be manufacturer's instructions as they should tell you how the generator is wired internally. I emphasise 'should' as in reality those instructions will likely be useless, but it's still important to have someone figure this out to determine exactly what can be achieved and how the generator should be earthed.

From your description I'm guessing it uses a centre tapped earth, which would give you 230V between lines and 115V between either line and earth.

If the above is correct, I'd forget about the set up you propose, with the two lines wired seperately to three phases and most certainly would not recommend omitting RCD protection. Without more information I don't think anyone here is going to be able to provide empirical answers to your questions, so we'd either need much more information or, more likely, you need someone on site who really knows their onions. Picking a random spark form the yellow pages wouldn't be an ideal way of getting you up and running with a reliable temporary supply.