Out of no where, starting today, my Siemens AFCI breaker tripped. It trips immediately every time I attempt to reset it. Nothing has changed in my house. I turned off all light switches and unplugged everything on the circuit yet it still trips. The breaker is probably about 8 years old (when the house was completely rewired by the previous homeowner). Are these breakers known to fail or become overly sensitive as they age? What's the life expectancy of these breakers? Any thoughts or recommendations? Thanks in advance.

Siemens Breaker


I'm at a lost...I bought a new AFCI breaker (expensive) but before swapping it out, I confirmed that the issue still exists. Also, before swapping it out, I swapped the two circuits since the bedrooms are split between two 15amp AFCI breakers (1 that keeps tripping and the other remains closed; no issue). When I powered back up the house, the breaker stays closed (unlike the other breaker). When I went back up stair to turn a light on to test, the breaker would trip immediately (this happened two more times/resets). This is where it gets weird, after the third time, the breaker stopped tripping. Any thoughts?

  • Base case test - what happens when you disconnect the circuit connected to it - does it then reset, or not? Use appropriate care and turn off the main when messing with the wiring, preferably,
    – Ecnerwal
    Commented Oct 11, 2017 at 1:46
  • It resets without tripping.
    – Paul
    Commented Oct 11, 2017 at 2:02
  • Can you swap the 15A QAF that's tripping for a 15A QAF2 and report back to us which LEDs on the new breaker light when the breaker trips? Either that, or you may need to start unwiring things from the circuit and capping them off one at a time, working your way from the far end towards the panel until you isolate where it's tripping... Commented Oct 11, 2017 at 2:44
  • Two thoughts, not enough for an answer. (1) You've got some exposed wiring there. While you're messing with this, absolutely consider trimming that down a bit. (Exposed wiring always makes me nervous; high-voltage wiring even more so.) (2) Try turning the master power off, then reset the AFCI, then turn master power back on while not touching the AFCI. Doing so will at the very least ensure that you aren't holding the AFCI closed when it wants to trip. (It's my preferred way to reset GFCIs. It may or may not actually help, but I can't see how it would hurt.)
    – user
    Commented Oct 11, 2017 at 19:56
  • @Paul Any second update? From reading your first update, I would guess the switch toggling the light had a bad contact, causing a fluctuating series arc when on...was that possibly the problem?
    – bobuhito
    Commented Jun 18 at 7:41

2 Answers 2


There is an easy way to find out if your AFCI is bad. Disconnect the circuit but not the neutral from the breaker and see if it resets. If it does reset your AFCI is working and somewhere in your circuit you are getting an arc. Exactly where can take some work.

Employ the normal troubleshooting method of disconnecting half of the devices and see if the AFCI trips. The you take half of the half and try it again. Whether the AFCI trips or not tells you which direction to trace. No trip you add to the circuit. Yes trip you work toward the breaker. Eventually you will find the problem device. If that's a little hard to digest then just start at one end of the circuit and begin disconnecting fixtures one at a time until you find the problem.

Good luck.


Put the circuits back where they were. You may be and try again. Always do one thing at a time when trouble shooting. AFCI can be finicky and can have issues if you cross phase. Bathrooms were split for a reason a/b phase.

  • Hello, and welcome to Home Improvement. Thanks for the answer; keep 'em coming. And, you should probably take our tour so you'll know how best to contribute here. Commented Jul 22, 2019 at 12:56

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