All Square D QO120 DF breakers tripping simultaneously, when they do trip.

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11bgrunt

Pragmatist
Location
TEXAS
Occupation
Electric Utility Reliability Coordinator
New house, less than six months old. QO dual function breakers were used on every single pole circuit. HVAC has been replaced and EC is almost camped out there. The trips are random but when one trips, they all trip. We isolated the four wire feeder and found random continuity between the bare #6 EGC and the insulated 2/0al neutral. All on source side of the panel. The dryer cord was found connected with white and green under the same screw but that plug was wired correctly. We have not been able to control the trip to determine cause.
HVAC manufacture said filters are in place, not their fault. Schneider said they never even heard of such a thing, can't be them.
We are looking for RFI as a possible cause. Panel loading has not lined up with trip times. Has anyone experienced this before?
This week the DF combos that can be AFCI only will be replaced with new AFCIs and we will see if that has an effect. This house is in a rural area far from town for what that is worth.
 
I guarantee the problem is on the line side of the breaker (Re : poco, utility, neighbor). AFCI's are bi-directional in the sense that they will trip even with a line side disturbance.
 
I guarantee the problem is on the line side of the breaker (Re : poco, utility, neighbor). AFCI's are bi-directional in the sense that they will trip even with a line side disturbance.

If a jumper was installed at the downline panel between the insulated neutral buss and the EGC, should these DF combos trip? As far as I know, this has not been tried yet.
 
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