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Actually reldas, there is a general misconception about the level of protection an RCD offers - some think it makes an electrical circuit perfectly safe and is a panacea for any and all electrical faults, including bad practice.

In reality, it doesn't. A 30mA unit doesn't even guarantee you won't get a shock - it does however mean that there is far less likelihood of that shock being fatal (but note that it does not guarantee that the shock won't be fatal)

Frank

Actually I was pretty sure that's what you meant, but you can't be too careful as they say - after all, others may be reading this too (although judging by some of the posts earlier, maybe not  )

George

One other small point (and I'm sure you've already thought of this, but just in case), is to be sure of the behaviour of your auto-switchover unit - it would be all too easy to overlook a connection this may make with everything plugged in.

The system I propose to use leaves the invertor has is in effect it only supplies Phase and neutral, same with the genny, this does not require a ground peg as it is an onboard unit.

It is my understanding that the phase would not give a shock because without an earth there could be no leakage thru me or anyone else, no circuit = no shock.

George

What I meant was that you need to ensure that your auto-crossover unit does not leave all the neutrals connected (ie just switches the live conductor), because if it does that, your genny and inverter neutrals will become bonded to earth through the "still connected" mains cable.

Also, in the case of the genny, you said it needs a chassis to chassis connection - if the chassis and neutral are bonded together at the genny, you'll essentially have a Circuit Protective Conductor (CPC) anyway (technically it may not be a true earth though).

however short of grabbing Phase and neutral lines togethor it is my understanding that it would not be possible to get a shock.

Usually, this is true, but it's still actually possible to get a shock from such a system by touching phase alone, despite popular belief to the contrary (even if unlikely). This is because of stray capacitance between the neutral and general mass of earth. Again, the level of shock would depend on many factors.

See http://www.tlc-direct.co.uk/Book/5.1.3.htm 

This offers an explanation with a nice little piccie (as they say a piccie can paint a thousand words). In fact, looking around that site, there's quite a bit of useful info there.

Is there a way of making Live and neutral dual contact safe (or at least safer?)

None that I am aware of - the problem is that electricty supply systems are designed to supply loads connected across phase and neutral, which is exactly what you become if you touch both live and neutral at the same time - the supply doesn't know if that load is a lamp, toaster, kettle, heater, TV, etc etc, or a person.

In the case of the mains, you hope that there is enough earth leakage through you to trip the RCD, but this is by no means certain.  The worst kind of shock (on any supply) would be to touch live with one hand, while touching neutral with the other (you'd take the full belt right across your chest - very very bad). All you can hope is that your own muscle spasms from the shock throw you off the contact before it's too late, but shocks like this can be fatal (and if fibrillation occurs, even being thrown off may not be enough).