FFS - Multiple breakers tripping at same time randomly for 2 years

[Moosifer]

This has been going on 2 years.
Usually in the evening a random selection of single pole breakers will trip simultaneously.
I checked all of the neutrals, cleaned the connection in the neutral bus bar where 2 pieces join and added some sheet metal screws to replace the screw that holds it to the panel right below the utility connection (things were good for 6 months after this). Last week I replaced the screw that joins the 2 sections of neutral bus with a bigger longer self tapper since the original had finally stripped out from triple checking it 100 times. Breakers tripped that night.

Residential millbank 200a house panel. Passthrough 100amp breaker to 100amp main subpanel. Neutral for 100a main subpanel connects directly below utility connection and neutral bar is past that. RV breaker (not used) and garage subpanel breakers in meter panel also (garage is barely used and basically has no load if the lights aren't on), plus maybe a hot water heater.
Neutral wire to 100amp subpanel 30ft away is probably 2/0 aluminum. Ground wire to subpanel is probably #4.

Neutral and ground are joined in the meter panel and not in the subpanel. Neutral bar etc. are definitely getting good connection through the meter panel to ground.
Ground bar has 3 good screws going into the panel.
We replaced the ground wire and added a second ground rod last week since resistance was a little high. At the same time all neutral connections were tightened etc. since I sent a new person to go figure it out and start at the beginning and assume nobody had done anything yet. Single pole breakers tripped the next evening randomly.

This house was gutted and we rewired the majority of it 2 years ago and this has been going on since then. New main subpanel and breakers inside with almost all new wire.
There should be no shared neutrals or neutrals touching ground. There are no events that cause the breakers to trip. Only 2 people live there and it will happen while they are sleeping. Usually at night or in the afternoon not during they day when they are using things.

There was one eaton 20a normal breaker, one eaton 20a gfci breaker, and the rest were eaton afci breakers (green ones).
Yesterday we swapped out 2 of the afci breakers with new ones (same kind). We also eliminated a few on lighting circuits and put in non-afci breakers to test things out. So 7 breakers tripped twice at 10pm last night. Mostly afci but also a normal single pole breaker, afci on both legs, all single pole 20a.
The 2 pole breakers have never tripped.

I had the power company out there today and load test the feed with a superbeast and he said it is all fine. He didn't want to test it but he did. It is a bit windy and I asked him to shake the lines a bit too while he was there but I doubt he did since he did a visual inspection when he pulled up.

I am just throwing time and money at this and getting absolutely nowhere.

 

[petersonra]

I hate intermittent problems like this.

If it was just the AFCIs we could blame it on unreliable technology. But GFCI breakers and regular breakers are normally very reliable. My guess would be there is an actual problem somewhere that is eluding you.

What happened at 10 pm last night? Did a POCO capacitor bank switch off maybe?

 

[Barbqranch]

Is the subpanel outside where someone could be messing with it? How about a trail cam?

 

[synchro]

Are the breakers that are tripping only in the 200A main panel, or are there any in the 100A subpanel that are also tripping?

... I checked all of the neutrals, cleaned the connection in the neutral bus bar where 2 pieces join and added some sheet metal screws to replace the screw that holds it to the panel right below the utility connection (things were good for 6 months after this). Last week I replaced the screw that joins the 2 sections of neutral bus with a bigger longer self tapper since the original had finally stripped out from triple checking it 100 times. Breakers tripped that night.

Is the self tapping screw threading into both parts of the neutral bus or just into the one at the bottom of the screw? I would think you'd want clearance in the top hole so that the screw pulls both sections of the bus together. I assume this is making sense based on your description, but maybe not since I don't have a picture of it.

A suggestion is to apply L-N loads to the section of the neutral bus that doesn't have the neutral wire coming from the service. That way you'll be putting some current across the joint between the two sections, and you can measure if there's any significant voltage drop across the joint.

 

[tthh]

The impression I got was a combo meter panel on the outside of the house and there is 100A breaker in that with no other breakers.

Very strange though. AFCI tripping is one thing, but the non-AFCI is another. I might be inclined to replace the 100A breaker and ask for a new meter. Not that those are high probability issues, but they are a common to the subpanel.

 

[synchro]

The impression I got was a combo meter panel on the outside of the house and there is 100A breaker in that with no other breakers.

You could be right. I was reading "100 amp main subpanel" as a 100A main breaker panel being used for the subpanel, iinstead of as the main panel for house.

 

[hbiss]

I can't see anything you thought to do would have anything to do with fixing this problem. If it were AFCI's yeah. GFCI's maybe. But regular breakers don't trip unless they are defective or needed to trip. And all of these at the same time at random?

Doesn't pass the smell test.

Are you sure the breakers were tripped, not turned off? The first thing that comes to mind is somebody tampering with them and turning them off. We've had that before.

The AFCI's should have diagnostics. What do they say tripped them?

-Hal

 

[Moosifer]

I hate intermittent problems like this.

If it was just the AFCIs we could blame it on unreliable technology. But GFCI breakers and regular breakers are normally very reliable. My guess would be there is an actual problem somewhere that is eluding you.

What happened at 10 pm last night? Did a POCO capacitor bank switch off maybe?

No idea on the POCO.

 

[Moosifer]

Is the subpanel outside where someone could be messing with it? How about a trail cam?

It's inside.

 

[Moosifer]

Are the breakers that are tripping only in the 200A main panel, or are there any in the 100A subpanel that are also tripping?


Is the self tapping screw threading into both parts of the neutral bus or just into the one at the bottom of the screw? I would think you'd want clearance in the top hole so that the screw pulls both sections of the bus together. I assume this is making sense based on your description, but maybe not since I don't have a picture of it.

A suggestion is to apply L-N loads to the section of the neutral bus that doesn't have the neutral wire coming from the service. That way you'll be putting some current across the joint between the two sections, and you can measure if there's any significant voltage drop across the joint.

Just tripping in the inside main subpanel. Self tapper is threaded into both sections of buss bar and panel and beyond - 1/4 screw in much smaller hole with a nut driver and lots of hard work.

 

[Moosifer]

You could be right. I was reading "100 amp main subpanel" as a 100A main breaker panel being used for the subpanel, iinstead of as the main panel for house.

It is a meter combo outside with a couple other 240 circuits and a big passthrough 100a feeding the inside subpanel with everything else on it. The inside one is having the issues.

 

[Moosifer]

I can't see anything you thought to do would have anything to do with fixing this problem. If it were AFCI's yeah. GFCI's maybe. But regular breakers don't trip unless they are defective or needed to trip. And all of these at the same time at random?

Doesn't pass the smell test.

Are you sure the breakers were tripped, not turned off? The first thing that comes to mind is somebody tampering with them and turning them off. We've had that before.

The AFCI's should have diagnostics. What do they say tripped them?

-Hal

The AFCI's just have the test button.

 

[Moosifer]

So yesterday afternoon things were tripping over and over (5pm Friday, why the heck wouldn't they trip at that time if they were gonna trip?).
It would be better if it wasn't 45 minutes away.

He sent pictures (all afci this time) Living room and master bedroom outlet afci breakers were the 2 constant ones.
I'm thinking maybe intermittent neutral to ground contact at an outlet or maybe there are shared neutrals and something plugged into an outlet in the house only draws a load and trips things every so often??? The additional breaker thing is just weird, why not just 2 breakers if it's a shared neutral?

Or rats, but it is a fairly small single story house and I believe they would have heard the scurrying. I've known these people previous to doing their electrical and I don't think they would have rats and not know it. It's clean and pretty quite in there. I had rats at my office and it would be hard not to notice. Electric traps that zap them work pretty awesomely.

Or as tthh said, perhaps it is the 100a breaker feeding the main subpanel. Or the meter?

 

[Moosifer]

Now 7:30am a single gfci for dining just tripped. Which was occasionally tripped with others but not every time.

 

[Dennis Alwon]

I would bet that there are a few neutrals being shared with other circuits. Of course they only trip when a load is added to it. Did you take a drill or something and go around and test every circuit? Bad power from the power company could be an issue but other houses in the neighborhood would have a similar issue.

If they are the only home on the transformer than I would beg the power company to change the trany out. Electronics are like voodoo-- since most are afci there must be something going on either in the trany or in some of the electronics in the home. i have seen phone chargers trip gfci receptacles. It happened at my home and at least 2 customers home. Also TV's, stereo, etc can have issues.

You can also try an older generation of the eaton afci. You may need to contact eatons afci support group

 

[synchro]

... There are no events that cause the breakers to trip. Only 2 people live there and it will happen while they are sleeping. Usually at night or in the afternoon not during they day when they are using things.

There was one eaton 20a normal breaker, one eaton 20a gfci breaker, and the rest were eaton afci breakers (green ones).
Yesterday we swapped out 2 of the afci breakers with new ones (same kind). We also eliminated a few on lighting circuits and put in non-afci breakers to test things out. So 7 breakers tripped twice at 10pm last night. Mostly afci but also a normal single pole breaker, afci on both legs, all single pole 20a.

A suggestion would be to put an in-line fuse of 10A or 15A in series with one of the breakers that's been tripping and has a relatively light load. Then if the fuse blows we can conclude that there was definitely an event which exceeded the current rating of the fuse, but we don't know by how much.
If the breaker trips and the fuse doesn't blow, it tends to point toward some other issue like an overvoltage or electrical noise causing AFCIs to trip without the presence of a large current. If the fuse doesn't blow you could then try an even smaller fuse if the load allows. This experiment wouldn't be 100% conclusive because we don't no how well the breaker and fuse would coordinate. But at least it might provide a clue about which direction you should proceed.

 

[hbiss]

Self tapper is threaded into both sections of buss bar and panel and beyond - 1/4 screw in much smaller hole with a nut driver and lots of hard work.

Or as tthh said, perhaps it is the 100a breaker feeding the main subpanel. Or the meter?

None of that makes any sense!

This sounds like the blind leading the blind here. Sounds like you are relying on the customer to provide your information. Have you actually witnessed a breaker trip?

Somethings not right with your story.

-Hal

 

[Moosifer]

I would bet that there are a few neutrals being shared with other circuits. Of course they only trip when a load is added to it. Did you take a drill or something and go around and test every circuit? Bad power from the power company could be an issue but other houses in the neighborhood would have a similar issue.

If they are the only home on the transformer than I would beg the power company to change the trany out. Electronics are like voodoo-- since most are afci there must be something going on either in the trany or in some of the electronics in the home. i have seen phone chargers trip gfci receptacles. It happened at my home and at least 2 customers home. Also TV's, stereo, etc can have issues.

You can also try an older generation of the eaton afci. You may need to contact eatons afci support group

I'll get someone to test some plugs before pulling them this morning.

 

[Moosifer]

None of that makes any sense!

This sounds like the blind leading the blind here. Sounds like you are relying on the customer to provide your information. Have you actually witnessed a breaker trip?

Somethings not right with your story.

-Hal

I agree. But they are very cool people and he has been sending me pictures with tripped breakers marked. I wonder if he isn't leaving some off part time to stop the tripping and eliminating shared neutrals in the process....

 

[Moosifer]

A suggestion would be to put an in-line fuse of 10A or 15A in series with one of the breakers that's been tripping and has a relatively light load. Then if the fuse blows we can conclude that there was definitely an event which exceeded the current rating of the fuse, but we don't know by how much.
If the breaker trips and the fuse doesn't blow, it tends to point toward some other issue like an overvoltage or electrical noise causing AFCIs to trip without the presence of a large current. If the fuse doesn't blow you could then try an even smaller fuse if the load allows. This experiment wouldn't be 100% conclusive because we don't no how well the breaker and fuse would coordinate. But at least it might provide a clue about which direction you should proceed.

I like that idea. I had a power meter on it for a few months after I sheet metal screwed the neutral and it never tripped at all. I will find and reinstall that.