Inductive Kickback Shielding on Adjacent GFCI Circuit ?

[pjn]

With the historic heat wave in the Pacific NW, I plugged in a portable condensing AC unit in my home office . This panel-protected AFCI circuit also serves a switch in another room, which is in a double gang box with a switch that is on a panel-protected GFCI circuit for that room. The GFCI panel breaker has been tripping , coincidentally beginning after I began running the floor AC unit in the office AFCI circuit.

These circuits do not share a neutral - there are no shared neutrals in the house (I know, because I wired this house myself).
The GFCI breakers and AFCI breakers (both Siemens) are on the same bus on the panel, but are far apart. I have not yet opened the panel to see if their neutrals are on the same bar.

Therefore, I suspect that inductive kickback from the AC unit is the cause of the GFCI trip on the othe circuit.

I really don't want to replace the GFCI panel breaker unless I can verify it's defective, and I'd prefer not to replace it with a plain panel breaker and and add a GFCI outlet.
So, I'd like to find a way to shield the GFCI circuit from any effects of the adjacent circuit.

Is there a code-compliant way I could apply a grounded shield to protect one switch from the other in the double-gang box? Or is my best option to break the switches out into two shielded single-gang boxes ?

 

[roger]

This borders on being a DIY question so please keep suggestions to what may actually be causing the problem and a solution without providing "how to" install or wire advice. That may not be possible but we will give it a try.

Roger

 

[ptonsparky]

I have had issues in the past that we resolved by applying snubbers at the inductive device. Contactor coil or very small motors.

IDK how to give less detail.

 

[Fred B]

Mike recently sent news letter out that talked about the new code requirement for GFCI protection on 30 and 50A circuits causing issues with AC units. There are some municipalities that are now adding exception to their local code to waive that requirement. I know that is for the large hardwired units but could see that the same process at work causing the tripping on the small plug in units.

 

[gar]

210629-0715 EDT

pin:

You list yourself as a software engineer. What does that mean? Do you have an electrical engineering degree? From what school?

There is something fishy with your neutral description. Do you have an understanding of how a GFCI works? Have you open one up and studied how it works? Have you gone to the Internet to find a discussion on how GFCIs work?

.

 

[kwired]

The "snubber" mentioned earlier is basically a RC network that absorbs the "kickback". Place it near the offending item producing the kickback.

 

[ptonsparky]

The "snubber" mentioned earlier is basically a RC network that absorbs the "kickback". Place it near the offending item producing the kickback.

Someday I will remember the proper term. Don’t hold your breath though.

The ones I have used in the past had different voltage ratings. A 130 volt worked where a 120 didn’t.

 

[pjn]

Thanks for the insight , folks. The snubber does appear to be the first option to try - Does A Listed NEMA 5-20R-form-factor snubber adapter exist?

 

[paulengr]

Thanks for the insight , folks. The snubber does appear to be the first option to try - Does A Listed NEMA 5-20R-form-factor snubber adapter exist?

As stated Snubbers are RC or diode networks.

 

[pjn]

As stated Snubbers are RC or diode networks.

That much I understand , I was hoping there was an off-the-shelf Listed product out there . I know what to do from here. Thanks

 

[roger]

I know what to do from here. Thanks

Good luck, hope you can resolve the problem.

Roger