Two in one out switching advice needed.

[ellal]

Thanks for the replies, but I'm still confused as to which switch would suffice.
Tbh I don't want to lay out that much on the TLC item if it's not necessary.

And this..

What are you supposed to do with the earths?

It's always been a question that the 240V output shows up an earth fault even when both methods of earthing suggested by the inverter manual (System earth or earthing rod) don't seem to work.

 

[flameport]

but I'm still confused as to which switch would suffice.

Any of them

Tbh I don't want to lay out that much on the TLC item if it's not necessary.

The Fusebox one is £50 - pretty much as cheap as you will get for such a thing.

The only other safe method is to have the whole garage on a suitably rated plug, and then have 2 socket outlets, one from the mains supply and the other for the inverter.
Changing over involves unplugging from one supply and plugging into the other one.