AFCI breakers tripping every 7 days

[rgsgww]

Hey hmk123 what really happened? Have you found out yet? I have this afci laying around that I never got the time to install...I want to know what happened before I slide this in.

[hmk123]

Sorry, we had visitors so I wasn't on here. It did trip again yesterday (Saturday). Both always trip at the same time. So this time, five minutes before I turned off the one to the plugs. Sure enought at exactly 8:48pm last night the other one tripped. So that breaker is supposed to only feed the lights (most of them recess lights). I checked the clock and it was to the minute. So next week (it will be now on Friday since it is on the seventh, not eighst day) I am going to turn the other breaker off (the ones with the lights) and see if the one that was shut off yesterday will trip by itself. I will take a look at the meter in the morning and see if it says DCSI .

[scrunchielaura]

Q1: The AT&T settop box, is it plugged into the "plugs" circuit that you turned off yesterday/Saturday?

Q2: Reading between the lines, I assume you have another TV and settop box elsewhere, correct?

[hmk123]

Yes, that settop box was on that circuit that was turned off. And yes, there are 3 other of their boxes in the house.

[RRW]

How a about a refrigerator going in to defrost mode on a regular schedule?

[hmk123]

The fridge was on the circuit that I turned off a few minutes before the one with the lights tripped. Also, the two breakers already did this when there were no appliances in the room (only the occasional tool usage). The lights have been in there ever since it has been doing this. I just don't get how anything on that circuit could be keeping time. We changed the light switches from dimmers to normal switches and it did not make a difference.

I still need to do a photo of the meter. But it does not say DCSI or TWACS on it.

[Mikey]

So next week (it will be now on Friday since it is on the seventh, not eighst day) I am going to turn the other breaker off (the ones with the lights) and see if the one that was shut off yesterday will trip by itself.

God, this is getting exciting!

[hmk123]

Sorry, no update last week because I forgot to pay attention. But both tripped again at the same time. I didn't realize it right away. So I did reset both breakers about 30 minutes later. Tonight, about 15 before they were supposed to trip, I turned off the other one (this is the circuit for the lights). Sure enough, now right to the minute the breaker with the plugs still tripped. I assume it now has to do something with the ground, since it is shared by both? I guess next thing is to swap one of them for a regular breaker and see if the regular one stays ok and the AFCI trips. This for sure is strange.

[Mikey]

I would repeat the experiment turning off the receptacles. I assume you haven't swapped one of them to the other service leg?

[hmk123]

I did that two weeks ago. I turned off the one with the receptacles and that time the lights tripped. So it is either one of them (or both if both are turned on) that trip exactly 7 days later.

[Mikey]

I'm betting on a problem on the common leg -- nothing to do with the two circuits.

[hmk123]

I agree. Unfortunately I don't know much about that. Where do I learn about the common leg? I guess I will google it :-) And what could cause that?

[Mikey]

Most of what you need to know has been previously posted in this thread. Summarizing everything -- all the 120V circuits in your house are divided between 2 "legs"; both of your problem breakers are connected to the same leg; I, for one (maybe the only one), suspect that a real arc fault is occuring on this leg somewhere else in the house, and your breakers are reacting to it.

[cattledog]

Mikey--

If the problem is somewhere else in the house and not on the two specific circuits which fault, how can the problem occur exactly seven days after the breakers are reset? You may be right, but what other circuits on that line would know when the breakers are reset?

Here's how I understand the problem statement. If, for example, he leaves the breakers off for two days after they trip, and then resets them, they will trip again after the same period of time as they would have if he reset them immediately after the fault. It is a fixed time from the reset, and not a fixed time in relationship to an external clock, or the first incident.

[Mikey]

I agree, and thought that originally, but somewhere along the line I got the idea that the problem occured on Sunday night, no matter when they were reset. Rereading the thread, I'm back to thinking it's 7 days --to the minute -- after they're reset. What happens, I wonder, if you reset breaker A at one time, and Breaker B 24 hours later?