Hello Bluetti Forum People,
I have finally activated Split Phase mode on my 2 AC300 Power Stations. Everything seems to be working well except the AC output from one side of the Fusion Box Pro is indicating “open ground”. One of the 2 surge protectors/circuit analyzers connected to each of the AC300 head units NEMA TT-30 AC outputs is indicating “open ground”. I believe this is the same issue that has made some people to not use the Fusion Box for connecting to a transfer switch or power distribution panel? Anyway, should I just use a neutral / ground bonding plug on the side that is having the “open ground” issue, or do I need to build or purchase the Y cable setup without the fusion box? Thank you. Greg
@knightstale04 Connecting the surge protector shows “open ground” because it does require grounding, and you cannot use a neutral grounding plug. The neutral grounding plug is not actually grounded.
Thank you so much for responding, but I am not sure I fully understand why the X phase output from one AC300 would not have the open ground, but the Y phase output from the other AC300 does have the open ground?
@knightstale04
In a split-phase system, the X and Y phases typically represent the two different firewires. The AC300’s TT-30 AC output receptacle is also single-phase, not part of a split-phase system.
Are you referring that one AC300 shows an open circuit while the other is grounded? Could it be because one of the AC300 units is connected to the grid? As the machine would also be grounded when connected to the grid.
Yes, the 2 TT-30 outputs send 120 volts to the master single phase (X) on one side and 120 volts to the slave single phase (Y) on the other. The master’s left side of the box, TT-30 (X) 120 v single phase output is grounded, but the slave’s right side of the box TT-30 (Y) 120 v output has the open ground. The very top four pronged, 240 volt L14-30 output produces the split phase that connects to my male L14-30 input plug that powers my distribution panel. The distribution panel’s grounding buss is connected to a grounding rod. This main panel also is the power entry point where the ground and neutral are bonded.
There are other AC300 users who have posted to this forum that the Fusion Box Pro has an issue with the slave side open ground, like I experienced with my Fusion box. My original question was to verify if I should use the same solution they recommended in plugging a neutral/ground bonding plug into one of the AC outputs on the slave AC300? Maybe this is not even an issue, because all my branch circuits terminate to GFCI AC outlets, and when I test the GFCI outlets they work perfectly on both (X and Y) sides of the split phase the AC300’s send into my distribution panel.
@knightstale04
Please avoid using a neutral-grounded plug, and it’s best not to use a GFCI plug, as it may cause tripping.
We recommend installing a dedicated outlet directly from the distribution panel for charging, bypassing the GFCI.