GFCI at 1200 amp main tripping when inverters come online.

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efrntzl

Member
Hi, I am working on project that is utilizing (5) Sunny Boy 15000TL's in Los Angeles. They are connected through a PV distribution panel, and then via 100A, 480V fused switch on the main 1200A swbd.

Its installed, and at the moment, whenever the inverters come online in the morning, it causes the GFCI circuitry on the 1200A main breaker to trip - shutting down the whole building. There were no issues with this breaker prior to install of PV system.

Curious if anyone has any suggestions on what might be causing this?

Thanks for any help you can offer!
 

GoldDigger

Moderator
Staff member
Location
Placerville, CA, USA
Occupation
Retired PV System Designer
Q: Does the trip happen when only one inverter comes online?
Q: What happens when you switch an inverter on after the normal morning turn on? If it trips then does it trip at turn on or when the inverter starts working after the five minute delay to qualify the grid?
Q: What is the GF current trip level set to on the breaker?

The "usual suspect" would be a redundant ground to neutral bond that only causes problems when the inverters are sourcing power.
 

ggunn

PE (Electrical), NABCEP certified
Location
Austin, TX, USA
Occupation
Electrical Engineer - Photovoltaic Systems
Q: Does the trip happen when only one inverter comes online?
Q: What happens when you switch an inverter on after the normal morning turn on? If it trips then does it trip at turn on or when the inverter starts working after the five minute delay to qualify the grid?
Q: What is the GF current trip level set to on the breaker?

The "usual suspect" would be a redundant ground to neutral bond that only causes problems when the inverters are sourcing power.

Assuming that there is an AC combiner panel to aggregate the inverters' output, is maybe a neutral to ground tie in that panel?
 

jaggedben

Senior Member
Location
Northern California
Occupation
Solar and Energy Storage Installer
I will just point out that interconnection on the load side of the building GFP is also a code violation. 705.32

Curious to see what the problem seems to be.
 

GoldDigger

Moderator
Staff member
Location
Placerville, CA, USA
Occupation
Retired PV System Designer
I will just point out that interconnection on the load side of the building GFP is also a code violation. 705.32

Curious to see what the problem seems to be.
A violation unless there is a separate GFP on the combined output of the inverters, which would maintain the GF protection for the building wiring system.
Or at least some inspectors will accept that argument.
 
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