Dual online UPS System vs Separately derived system

[lhannon]

I was wondering if anyone else has run into having to determine if a larger dual online UPS is considered a separately derived system?
I thought they were until the manufacture of this particular UPS was able to confirm that the input neutral and output neutral are solidly connected and do not pass through the conversion process.
So in this particular installation, it would not be considered a separately derived system and the neutral and ground would not be re-bonded in the panel that the UPS serves.
It was not documented anywhere in their installation instructions, but lesson learned. I would appreciate any opinions.

 

[ron]

This happens often when you bring a neutral with the input to the module, which happens a lot in 120/208V systems. The neutral is often is solidly connected from input to output for the bypass'.