I recently replaced my home's load center. As part of that surgery, my breakers were also updated to (combination) AFCI breakers. My house has many Multi-wire branch circuits, so I also got a couple double-pole AFCI breakers to accomodate this wiring. I'll be re-wiring my house in the near future as part of a more comprehensive renovation that I'm planning, but I'm hoping to not have to do any re-writing currently since it'll be throwaway work.

My basement lights are on one of these multi-wire circuits. There is a three-way switch in the hall that, when turned on, immediately trips the (double pole) AFCI breaker. Are there any specific troubleshooting steps that I should take, or do I just investigate it like any other AFCI trip? All the other lights/outlets on the circuit are OK -- the breaker only trips (and will always trip) if the hallway light is turned on.

Here's the first switch. The problematic one is the bottom switch of the tandem switch. first switch box first switch box interior

The second of the switches is the one on the right. I removed the switch on the left, it's not related (it controls a different light).

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  • Did you check the wires in the light yet ? Problem may be in light. – user101687 Jun 20 '19 at 4:42
  • What type of lighting? The wiring may be fine, I have had issues with several brands of arc fault’s not working with modern fluorescent ballast and even more problems with dimmers on arc fault circuits. The manufacturer(s) said it was because of the method the electronics used that caused the issue. My state has an exception to the NEC regarding arc faults on devices known to have tripping issues (standard breakers are allowed in this case). Oregon amendments section 305 table 1E. – Ed Beal Jun 20 '19 at 13:47
  • I'll remove the bulbs to see if it changes anything as per robert's and ed's suggestion. AFAIK it's LED bulbs in there. I pulled two of them and one is an IKEA bulb and the other is a Philips bulb, both LEDs. – atanamir Jun 20 '19 at 18:03

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