WiremanWireman · AFCI breaker keeps tripping: troubleshooting for electricians · 2023 NEC ·
AFCI breaker keeps tripping
Real arcs, shared neutrals, neutral-to-ground contact and appliance trips.
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How it works
An AFCI watches the current waveform for the signature of arcing: a loose connection sparking or damaged cord insulation. Most also trip on a small ground fault (around 30 mA). Many “nuisance” trips turn out to be wiring problems the AFCI is correctly catching.
Every question and answer in this guide. Tap “Step by step” to walk through it.
- When does it trip?
- When one appliance runsThe appliance’s arc signature
- Right away, with nothing onTest: Check the neutralExpect: Neutral on the breaker, used only by this circuit, and open (OL) to ground.
- Neutral on the bar, not the breakerNeutral landed wrong
- Neutral shared with another circuitShared neutral (multiwire circuit)
- Neutral near 0 Ω to groundNeutral touching ground
- All correctBreaker off: open the receptacles and switches on the circuit. Any loose, back-stabbed or darkened connections?
- YesA real arcing connection
- NoPossibly a bad AFCI
- RandomlyTest: Check the neutralExpect: Neutral on the breaker, used only by this circuit, and open (OL) to ground.
- Neutral on the bar, not the breakerNeutral landed wrong
- Neutral shared with another circuitShared neutral (multiwire circuit)
- Neutral near 0 Ω to groundNeutral touching ground
- All correctBreaker off: open the receptacles and switches on the circuit. Any loose, back-stabbed or darkened connections?
- YesA real arcing connection
- NoPossibly a bad AFCI