• We will be performing upgrades on the forums and server over the weekend. The forums may be unavailable multiple times for up to an hour each. Thank you for your patience and understanding as we work to make the forums even better.

Inductive Kickback Shielding on Adjacent GFCI Circuit ?

Status
Not open for further replies.
P

pjn

Member
Location
Oregon
Occupation
Software Engineer
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

roger

Moderator
Staff member
Location
Fl
Occupation
Retired Electrician
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
 
Fred B

Fred B

Senior Member
Location
Upstate, NY
Occupation
Electrician
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.
 
G

gar

Senior Member
Location
Ann Arbor, Michigan
Occupation
EE
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

kwired

Electron manager
Location
NE Nebraska
Occupation
EC
The "snubber" mentioned earlier is basically a RC network that absorbs the "kickback". Place it near the offending item producing the kickback.
 
P

pjn

Member
Location
Oregon
Occupation
Software Engineer
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?
 
Status
Not open for further replies.
Top