Amazing Little-Known Circuit Breaker Test 

I actually never heard of that trick. Where I work we usually use Eaton BR style panels and breakers. For those that aren't familiar with this particular panel, the AFCI, Dual function and also GFCI, if I'm not mistaken, breakers have a small red LED in the test button that blinks a specific number of times after you reset it following a trip. The number of blinks corresponds to the type of fault that caused it to trip. What I've experienced, not so much now, but about 8 to 10 years ago when I was first getting into the trade as an electrician, motors, vacuum cleaners being the largest culprit, caused most nuisance trips with AFCIs in the days before the technology matured enough to tell the difference between normal arcing and dangerous arcing conditions. Another thing I've heard but never experienced myself, in the early days of AFCI, were dimmer switches. Because a dimmer switch works by chopping off part of the AC sine wave thereby varying the RMS voltage supplied to the luminaire, supposedly this didn't work as well with some brands of AFCIs when dimmed to a certain level, with some brands of dimmers having more trouble than others.

Cool tip, had no idea👍🏻. Is this true for all brands or just square D dual function breakers?