Changeover switches reccomendations (and what do the regs say)

[jimseng]

Hello.
My electrician was questioning the regs regarding changeover switches as he has not fitted one to an inverter before. I intend to have two changeover switches, one to connect my grid DB to the load output of the inverter in the case of a long term power cut and one to connect the load DB to the grid in case of an inverter failure. I know others on here have done exactly this so I thought I would ask for recommendations as to what make/model of switch people feel is suitable. My inverter is a 10k single phase and the supply breakers will most likely be rated at 63 amp.

The electrician has always fitted large 3 position changeovers for large generator installations. His concern is whether there is a regulation that the changeover switch should have an off position, in other words a 3 position switch.

 
I was considering something that would be along the lines of the image below, din mounted in a neat box. rated at 125a. However this unit is £17 + vat which he thought sounded cheap and nasty.
It also seems to be a one or other position, not and on - off -on. Does anybody know if there is any reg or code of practice that prohibits this type of changeover for what I want to do?

Any particular units I should be looking at?

 

[JohnMo]

42 minutes ago, jimseng said:

output of the inverter

So is this an inverter that will run in Island mode, most don't