Nuisance Tripping AFCI Circuit Breakers

[Leo1]

I have a new single family dwelling with Square D single-pole dual function AFCI and GFCI circuit breakers that over the period of a week approx. 12 will trip. I reset them and within appox. a week they trip again. Some the AFCI and GFCI circuit breakers are in rooms not occupied and have no load on them. The home is off the grid, its primary power is by an 8kW photo-voltaic and battery system that handles the home well for about 80% of time. When the dryer or range is used (or protracted period of cloud cover) a supplemental small diesel generator handles the surge in loads.

I would greatly appreciate all troubleshooting tips to help me address the tripping AFCI and GFCI circuit breakers. The home was completed new in early 2017 and went through multiple state electrical inspections passing all with Green tags. The PV system and diesel generator factory reps have been to the home and verified wiring of their respective systems are correct. No obvious defective equipment/loads on the CBs have been found causing the problem.

Thank you.

 

[Ponchik]

If you have ZERO load on the circuits then it most likely is an EGC touching the grounded conductor. It does not have to be a good solid connection.

Is the circuit dedicated to the unoccupied rooms only?

 

[Daniel malack]

I had a similar problem with a portable generator on a new construction job. I kept finding the breakers tripped. I'm thinking it was a grounding problem at the generator. If you drove a rod at gen set disconnect it. If you didn't drive a rod drive one..

Sent from my SM-T350 using Tapatalk

 

[Ponchik]

I had a similar problem with a portable generator on a new construction job. I kept finding the breakers tripped. I'm thinking it was a grounding problem at the generator. If you drove a rod at gen set disconnect it. If you didn't drive a rod drive one..

Sent from my SM-T350 using Tapatalk

How does the generator on the line side of the breaker have any effect on the AFCI/GFCI breaker? Both breakers manage their load side only.

 

[Daniel malack]

Once had an elevator trip a gfi breaker. Wasn't even in same panel. When I pressed the button on the elevator the breaker tripped. Took me weeks to find do it. I don't know why.

Sent from my SM-T350 using Tapatalk

 

[peter d]

I can pretty much guarantee that the problem is on the line side of the breakers, not the load side.

Driving a ground rod is a waste of time, it will not solve the problem. The problem is dirty power causing the electronics in the DF breakers to go haywire.

 

[ramsy]

1) If inverted secondary DC power causes noise in Alternating-Current loads, it could trigger an AFCI fault algorithm.
Dual-Function breakers should indicate if the trip was triggered by AFCI or GFCI functions.

2) If neutral current could bypasses a GFCI breaker, returning to a secondary power supply, it would trip the GFCI.
If circuits pass Megger, some secondary power neutral current may not be returning thru the breaker pigtail

 

[curt swartz]

I can pretty much guarantee that the problem is on the line side of the breakers, not the load side.

Driving a ground rod is a waste of time, it will not solve the problem. The problem is dirty power causing the electronics in the DF breakers to go haywire.

I agree with Peter.

I wired an off the grid house a couple for years ago. There are probably 80+ standard Square D AFCI breakers and to my knowledge none have ever tripped.
There was a separate building that the homeowner wanted to use as a big kids bedroom when they had parties. The building was originally classified as a workshop on the plans and because of some politics in the city it was going to take months to go through the process to get it reclassified as living space. The building met all the building/safety codes to be a bedroom (egress windows, closet, fire sprinklers, HVAC, Lutron Homeworks shades lighting). Since the city considered it a workshop and the homeowner considered it living space I decided to us a DF breaker so provide GFCI protection for workshop and AFCI for living space.

The DF breaker was tripping at least one a week.
the only thing on this circuit was 8 receptacles and the wires did not share boxes with any other circuits other than in the panel. I megged the circuit and could not find any problems. I replaced the breaker with a standard AFCI and it hasn't tripped since.

Moral of the story..........Square D DF breakers are crap.

 

[Leo1]

Thanks everyone for the great input!