Hi doccuke, I also have a Proform 600 LT tradmill and I am facing the same issue with tripping of AFCI breaker. Can you please let me the model of tripp-lit Isobar surge protector u bought? There are quite a few so wanted to confirm. On another note, Proform recommends using surge protector with one outlet. I went across tripp-lit website but didn't found one outlet, all were multi outlet.

I had a similar problem with a projector screen motor, that was knocking the AFCI off on a *different* circuit. In other words, this was a crosstalk effect from one circuit to another. The problem only happened if the AFCI circuit was running at least ~100 watts of power (either incandescent lights, and/or my laptop charger and other minor electronics), and the project screen was moved up or down. If the AFCI circuit had no significant power (ie just some minor electronics), it would not trip.

I bought a Tripp-Lite isobar "isoblock-2.0" surge suppressor, installed it on the outlet for the projector screen motor and haven't had any problems since then.

The project screen motor was a Draper Access motor.