Bonding/grounding and AFCI breakers

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Phillip Land

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Location
Rome, Ga, US
Hi,
So I have a problem that I need help with. I am going to layout the installation as I saw it and leave out my attempts to correct problem.

New single family dwelling unit

200 amp service with main breaker outside in combination meter/disconnect can

* 2 ground rods with #6 copper to neutral/ground
buss in outside disconnect

* 40 circuit interior panel fed with 4/0 4-wire al
ser feeder in garage
* neutrals and eq grounds separated in panel
* 2 eq ground bars connected with #4 copper
looping around panel (I don't know why the
can wasn't sufficient)
* #4 copper from rebar ground in garage to eq
ground bar in inside panel
* #8 copper from gas manifold in crawlspace to
neutral bar in panel

Problem:
Multiple Afci breakers randomly trip every couple of months for no apparent reason, even on sunny days
I have tried a few solutions that did not correct problem

Any suggestions?
 
Brand and age of breakers?

Simple experiment: swap tripping AFCI breakers with non-tripping ones to see whether the breaker(s) or the circuit(s) is the problem.
 
If these aren't dual function (AFCI & GFCI) breakers, then you might try as an experiment, replacing the breakers with a GFCI only breaker. If they still trip, you know its a ground fault problem.

But to be honest, since the trips are random, I would suspect the breakers themselves or some sort of interference such as a Ham radio or similar near by.

You could also contact the breaker mfg and ask them for the latest model of the breakers and see if that helps.
 
Phillip Land said:
Hi,
So I have a problem that I need help with. I am going to layout the installation as I saw it and leave out my attempts to correct problem.

New single family dwelling unit

200 amp service with main breaker outside in combination meter/disconnect can

* 2 ground rods with #6 copper to neutral/ground
buss in outside disconnect

* 40 circuit interior panel fed with 4/0 4-wire al
ser feeder in garage
* neutrals and eq grounds separated in panel
* 2 eq ground bars connected with #4 copper
looping around panel (I don't know why the
can wasn't sufficient)
* #4 copper from rebar ground in garage to eq
ground bar in inside panel
* #8 copper from gas manifold in crawlspace to
neutral bar in panel

Problem:
Multiple Afci breakers randomly trip every couple of months for no apparent reason, even on sunny days
I have tried a few solutions that did not correct problem

Any suggestions?
Click to expand...
Rebar #4 should be to MM.
Gas #8 should be to EG bar in panel.
IDK of that will change why or when the AFCIs trip.
 
Phillip Land said:
Hi,
So I have a problem that I need help with. I am going to layout the installation as I saw it and leave out my attempts to correct problem.

New single family dwelling unit

200 amp service with main breaker outside in combination meter/disconnect can

* 2 ground rods with #6 copper to neutral/ground
buss in outside disconnect

* 40 circuit interior panel fed with 4/0 4-wire al
ser feeder in garage
* neutrals and eq grounds separated in panel
* 2 eq ground bars connected with #4 copper
looping around panel (I don't know why the
can wasn't sufficient)
* #4 copper from rebar ground in garage to eq
ground bar in inside panel
* #8 copper from gas manifold in crawlspace to
neutral bar in panel

Problem:
Multiple Afci breakers randomly trip every couple of months for no apparent reason, even on sunny days
I have tried a few solutions that did not correct problem

Any suggestions?
Click to expand...
The grounding connections and the AFCI tripping are not related each other. AFCIs nuisance trip.
 
LarryFine said:
Brand and age of breakers?

Simple experiment: swap tripping AFCI breakers with non-tripping ones to see whether the breaker(s) or the circuit(s) is the problem.
Click to expand...
Homeline about 3 years old and they are DF not just AFCI
It's not the same ones that trip each time - sometimes only 5 trip and sometimes its as many as 8
 
electrofelon said:
FIFY 🐈.
I am not a fan whatsoever of AFCI's but everyone jumps to nuisance tripping when, IMO, vast majority of problems are wiring issues.
Click to expand...
What wiring problems could exist where this would happen like that?
I have heard that incorrect grounding and bonding can lead to these issues and I've ruled out Ham radio interference because none of his neighbors are having problems

I've also made sure that all the connections in the panels are tight
 
ptonsparky said:
Rebar #4 should be to MM.
Gas #8 should be to EG bar in panel.
IDK of that will change why or when the AFCIs trip.
Click to expand...
I told him that about bringing the rebar ground to the MM and I already moved the gas bonding to the eq ground bar even though, IMO, it should go out to the MM
He doesn't want to spend the money patching at this point
 
Phillip Land said:
What wiring problems could exist where this would happen like that?
I have heard that incorrect grounding and bonding can lead to these issues and I've ruled out Ham radio interference because none of his neighbors are having problems

I've also made sure that all the connections in the panels are tight
Click to expand...
I'll bet 90% of the time AFCI trips (assuming relatively new breakers, last four or five years or newer) are either neutrals from different circuits tied together in a box somewhere, or a neutral to ground bond from say a neutral hitting the EGC in a recep box or a nail thru a cable. That said, it is odd to have a bunch of different circuits trip. Did you do the wiring in this place?
 
Last one with several circuits I had turned out to be the siding/deck guys used the longest nails/screws I have ever seen!
I know were allowed a 1 -1/4 from the surface or whatever but I dont think any siding guys know this or care.
I had to turn a beautiful living room into Swiss cheese, cutting access holes with the 4" hole saw.
I finally found it by disconnecting the home runs in question, at both ends and using a megger on the low setting, 1000V I think.
Just a hour of prep, 30 second test and you'll know if the romex is bad.
 
tortuga said:
Last one with several circuits I had turned out to be the siding/deck guys used the longest nails/screws I have ever seen!
I know were allowed a 1 -1/4 from the surface or whatever but I dont think any siding guys know this or care.
I had to turn a beautiful living room into Swiss cheese, cutting access holes with the 4" hole saw.
I finally found it by disconnecting the home runs in question, at both ends and using a megger on the low setting, 1000V I think.
Just a hour of prep, 30 second test and you'll know if the romex is bad.
Click to expand...
Use your fault locator. stick Probes to sheetrock. It works just as if you were looking for a ground fault on buried underground. Saves a lot of holes.
 
electrofelon said:
I'll bet 90% of the time AFCI trips (assuming relatively new breakers, last four or five years or newer) are either neutrals from different circuits tied together in a box somewhere, or a neutral to ground bond from say a neutral hitting the EGC in a recep box or a nail thru a cable. That said, it is odd to have a bunch of different circuits trip. Did you do the wiring in this place?
Click to expand...
No I didn't do the wiring and the breakers would immediately trip under the circumstances you suggested. Sometimes a whole month will go by with no tripping
 
Phillip Land said:
I told him that about bringing the rebar ground to the MM and I already moved the gas bonding to the eq ground bar even though, IMO, it should go out to the MM
He doesn't want to spend the money patching at this point
Click to expand...
Gas lines do not qualify as a GEC, it is only being bonded, so taking it to the panel ground bar is ok.
 
hillbilly1 said:
I’ve seen those used outdoors on underground cables, how well do they work indoors? I know the guy trying to sell them said you had to wet the ground sometimes to get it to work. Seemed to work real well outdoors though.
Click to expand...
I used mine to find a nail the siding guys drove into a 14/3. Isolated both ends and proceeded as normal putting the probes to the sheet rock.

I taped saltwater spoked sponges to the probes for a fault located under a concrete driveway.
 
hillbilly1 said:
Gas lines do not qualify as a GEC, it is only being bonded, so taking it to the panel ground bar is ok.
Click to expand...
Yes, I know the gas line is just "bonded" but if you look at the codebook that they follow, it specifies taking it to the service neutral not the eq ground bar which is where they landed it, except it should have been outside in the MM, not the mlo panel. it's redundant anyway, IMO, because it's already bonded through eq grounding conductors at the furnace, stove, dryer..., etc
All bonding and grounding should be done at one point when practical. Oh, and I just love that you can use an eq grounding conductor as a gec. And they wonder why grounding/bonding is one of the most misunderstood articles in the codebook...
 
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