Steve.,

You did bring up a good poing with secondary injection as far from my experince the secondary injection is done best when the 1600 amp brekaer is drawed out { removed } and do the test and really one thing I will addressed to OP is get the power monitor and record for next couple days to see if the surge or dip of voltage show up ditto with current drawage.

Now for ground fault you have to check it very carefully with it I will not set the GFI over 200 amp the most any higher you have to get the RFI from the manufacter to advoid any issue with the set up.

I have see plenty 277v ground fault show up from time to time and you will have to look at the 277 lighting circuit that useally most common curpits.

Merci,Marc

Pas de problme,il marche n'est-ce pas?"(No problem, it works doesn't it?)