Helmet fire:
I've talked to the flight test dept @ the CAA and also our certification authority for NVIS.
Basically it all revolves around DO275, but remember that the NVG's are only a small (though crucial) element of the NVIS. There is a bottom line and that is in THIS country it would seem that certification will not cater for common power supplies to the two tubes.
The suggested industry standard too, is GEN III. However GEN2+ might work dependent on the operating environment (urban/rural etc).
I'll give you the contact details of the NVG guru over here who is only too happy to assist you personally - especially as he is a bloody aussie too! - PM me for more.