Weird AFCI tripping problem


Old 04-28-15, 08:15 AM
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Join Date: Apr 2015
Location: USA
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Weird AFCI tripping problem

I purchased a home that was built in Georgia in 2014 and ever since moving in the AFCI breakers trip a lot. Though they are not as sensitive now (used to be we would turn on one light switch and count a couple seconds before turning on another) they still trip fairly often. All the electrical work is under warranty so I have had it looked at. Of course the day the electrician came none of the breakers would trip, but he tightened up a couple connections and the breakers trip less frequently. It has probably been six months and I'm about to have the electrician come back because I do not think the problems happening should be occurring. I am looking for some opinions on what could be wrong so I can ask the electrician. My concerns I am looking for input on:
1. Some light switches (mainly the ones that control bathroom fans) will cause multiple AFCI breakers to trip and not just the one that the light switch in question is on. Five AFCI breakers all at once when all the other lights and appliances in the house are off is typical. Usually this happens at night and can be difficult to replicate during the day. There are no daylight controlled features in the house or appliances that only come on at night.
2. One light switch/bathroom fan combo imparticular will trip other circuits with AFCI breakers and continue running without tripping its own AFCI protected circuit.

How is a light or fan on one circuit able to affect other circuits?
Your input is greatly appreciated.
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Old 04-28-15, 10:52 PM
Nashkat1's Avatar
Join Date: Mar 2012
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How is a light or fan on one circuit able to affect other circuits?
It sounds like you may have a wiring problem. Because AFCI protection is provided from the panel for the entire circuit, any problem anywhere down the line can cause the breaker to trip.

Also, no contact can exist between an AFCI protected circuit and any other circuit. Sometimes even close proximity can cause tripping, if the insulation or the conductor cross-section is compromised.

A common problem in many installations is that the installer will overtorque the bonding screws on the breakers. More tightening won't help that, of course. Cutting off the damaged piece, stripping a new section, and tightening that to the specification printed on the panel label usually will.

Usually this happens at night and can be difficult to replicate during the day.
Have you noticed whether it happens more when it's raining? Or more during one season of the year?

The root question here is whether you notice a change in the occurrence with any environmental change. If so, that could point to the nature of the problem.
Old 04-29-15, 06:09 AM
Tolyn Ironhand's Avatar
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Is this a new home or just an upgraded electrical service? What brand of panel/breakers are they?
Old 04-29-15, 07:15 AM
chandler's Avatar
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If you even have one grounding wire touching a neutral at a fixture, it will trip one if not more AFCI's. Found this out when upgrading my cabin electrical. The PO tried to use a ground for a neutral at a switch. Constantly tripped two AFCI's until I dug deeper to find the error. Not sure if that is your problem, but I'd check to be sure.
Old 04-29-15, 08:37 AM
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Join Date: Apr 2015
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I should have been a little more clear. The house itself was built in 2014, so yes, new construction. The panel is Siemens, and the breakers are all Siemens. From what I can tell GFIs for many of the outlets and big appliances and AFCIs for the lights. It is one panel - I have read in places that some sort of sub panel is becoming popular that helps with nuisance tripping, and I definitely don't have one of those. The builder was pretty cheap with the materials used, so I suspect the quality of the panel is no different.

Thanks for the input so far from everyone. In regard to the problem occurring at night and weather related causes, it has tripped more frequently lately with some rain we have been having. Also it is starting to get humid again now that summer is approaching, so that could be having an effect too. I'll have to keep it in mind.

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