AFCI faults caused by rural power outages

[Jake44]

In a new home out in the country the customer tells me that whenever the rural electric supplier has an outage on his line he experiences random tripping of AFCI breakers. The service is a 200 A meter pedestal with a 200A main and an additional space. A properly sized grounding conductor was ran about 100 ft with the feeder to the house. In the house panel the neutral is bonded to the can. there is an footing ground and a driven ground rod also. I am wondering if removing the bonding screw and putting all grounds on a grounding bar would correct this problem. I have no idea what nature of faults the power company is having. They seem to be pretty frequent. Does anyone have any other ideas as to what could cause random tripping of AFCIs?

 

[Little Bill]

I don't know what to tell you about the AFCIs tripping but there is a problem here. You said there was a disconnect outside at the meter. If that's the case, the inside panel is a subpanel and the neutral should not be bonded to the can or the EGC bar. Can't imagine this causing the trips but is certainly not correct.

 

[ActionDave]

In a new home out in the country the customer tells me that whenever the rural electric supplier has an outage on his line he experiences random tripping of AFCI breakers. The service is a 200 A meter pedestal with a 200A main and an additional space. A properly sized grounding conductor was ran about 100 ft with the feeder to the house. In the house panel the neutral is bonded to the can. there is an footing ground and a driven ground rod also. I am wondering if removing the bonding screw and putting all grounds on a grounding bar would correct this problem. I have no idea what nature of faults the power company is having. They seem to be pretty frequent. Does anyone have any other ideas as to what could cause random tripping of AFCIs?

The neutral has to be bonded to the grounding electrode and the can somewhere and only once to make the electrical system safe. There is no magic about connecting anything to the earth so moving equipment grounding conductors inside the panel isn't going to change nuisance tripping of AFCIs. There is well known and documented issues with AFCIs. All you can do is make sure there are no neutral to ground faults on any of the circuits and start swapping them out with the newer AFCIs.

 

[Jake44]

The neutral has to be bonded to the grounding electrode and the can somewhere and only once to make the electrical system safe. There is no magic about connecting anything to the earth so moving equipment grounding conductors inside the panel isn't going to change nuisance tripping of AFCIs. There is well known and documented issues with AFCIs. All you can do is make sure there are no neutral to ground faults on any of the circuits and start swapping them out with the newer AFCIs.

Currently the neutral is bonded to ground at both ends. The meter pedestal is the actual service panel. My understanding is that is where the main bonding jumper should be. Beyond that point neutral and ground should not tie together, isolating the neutral in any downstream panel. So in the house the bonding screw should be removed and all grounds removed from the neutral buss and bonded to the can along with the service ground, the footing ground and the ground rod. This is doable, but I just don't know if that will fix the problem.

 

[texie]

Currently the neutral is bonded to ground at both ends. The meter pedestal is the actual service panel. My understanding is that is where the main bonding jumper should be. Beyond that point neutral and ground should not tie together, isolating the neutral in any downstream panel. So in the house the bonding screw should be removed and all grounds removed from the neutral buss and bonded to the can along with the service ground, the footing ground and the ground rod. This is doable, but I just don't know if that will fix the problem.

Correct assuming you have a n EGC run from the main to the house. But likely not the issue with your AFCIs tripping.

 

[ActionDave]

Currently the neutral is bonded to ground at both ends. The meter pedestal is the actual service panel. My understanding is that is where the main bonding jumper should be. Beyond that point neutral and ground should not tie together, isolating the neutral in any downstream panel. So in the house the bonding screw should be removed and all grounds removed from the neutral buss and bonded to the can along with the service ground, the footing ground and the ground rod. This is doable, but I just don't know if that will fix the problem.

It won't fix your problem and as has been said you need to make sure there is an EGC back to the meter ped. This is an area that is a little fuzzy. In Colorado, for a long time the wires between the meter ped and the house or structure were considered power company wires and the bond was made at the main at the house or structure. This was perfectly safe because there was never going to be any other metallic paths between them.

 

[mbrooke]

In a new home out in the country the customer tells me that whenever the rural electric supplier has an outage on his line he experiences random tripping of AFCI breakers. The service is a 200 A meter pedestal with a 200A main and an additional space. A properly sized grounding conductor was ran about 100 ft with the feeder to the house. In the house panel the neutral is bonded to the can. there is an footing ground and a driven ground rod also. I am wondering if removing the bonding screw and putting all grounds on a grounding bar would correct this problem. I have no idea what nature of faults the power company is having. They seem to be pretty frequent. Does anyone have any other ideas as to what could cause random tripping of AFCIs?

When short circuits occur on overhead power lines there is typically an arc. The ripple from that arc will show up on the secondary 120/240, where the AFCIs will think its taking place on a branch circuit and trip.

 

[ramsy]

There is well known and documented issues with AFCIs. All you can do is make sure there are no neutral to ground faults on any of the circuits and start swapping them out with the newer AFCIs.

Yes, AFCI instructions document the device pigtail is landed on neutral bus, and load neutral Is landed on AFCI breaker.

AFCI load neutral must float until terminated at breaker or load.

New AFCi's will do the same thing, If Sub-panels bond neutral to ground.

 

[Jake44]

Yes, AFCI instructions document the device pigtail is landed on neutral bus, and load neutral Is landed on AFCI breaker.

AFCI load neutral must float until terminated at breaker or load.

New AFCi's will do the same thing, If Sub-panels bond neutral to ground.

in addition to correcting the bonding, does any one think a surge suppressor installed at the service panel (1st Panel) would help cut down on the nuisance tripping?

 

[ramsy]

Did you contact the breaker manufacturer technical support, who may be familiar with tis issue?

 

[Briney]

in addition to correcting the bonding, does any one think a surge suppressor installed at the service panel (1st Panel) would help cut down on the nuisance tripping?

I just built new home with Square D QiO 200 amp panel with back up generator.
I installed SQ D surge protector and used AFCI breakers in some required circuits as well as AFCI receptacles at the first device of some other circuits.
We’ve had multiple outages up here in northern Adirondacks due to heave rains and downed trees on power lines.
Had to disconnect generator for issues from manufacturer , and during recent outage due to tree fall, had issue only with arc fault breakers tripping, but not AFCI breakers( AFCI breakers didn’t trip when Generator was operational). So, apparently the breakers located at panel may have more sensitivity , while regular breakers didn’t affect the receptacles..
But to answer, your original question- the surge protector was a non issue.

 

[Briney]

I just built new home with Square D QiO 200 amp panel with back up generator.
I installed SQ D surge protector and used AFCI breakers in some required circuits as well as AFCI receptacles at the first device of some other circuits.
We’ve had multiple outages up here in northern Adirondacks due to heave rains and downed trees on power lines.
Had to disconnect generator for issues from manufacturer , and during recent outage due to tree fall, had issue only with arc fault breakers tripping, but not AFCI breakers( AFCI breakers didn’t trip when Generator was operational). So, apparently the breakers located at panel may have more sensitivity , while regular breakers didn’t affect the receptacles..
But to answer, your original question- the surge protector was a non issue.

Typo in last response- should read “had issue only with arc fault breakers tripping, but not AFCI RECEPTACLES ( AFCI breakers didn’t trip when Generator was operational).”

 

[don_resqcapt19]

AFCIs can see arc signatures that originate on the line side of the AFCI, but there would be a lot of attenuation of the arc signature from a fault on the primary side of the transformer.

 

[Briney]

AFCIs can see arc signatures that originate on the line side of the AFCI, but there would be a lot of attenuation of the arc signature from a fault on the primary side of the transformer.

So , apparently, a tree did come down across both lines at 4160v which caused tree to go on fire. There was a transformer nearby at pole. So I assume this was enough to cause a condition for AFCI breaker to go into a tripped position but not affect AFCI receptacle feed from regular breaker.