So, got my Flex 3403 in the other day and been playing around with it in my apartment bedroom...yeah...well the circuit breaker for the room is 15 amps and the Flex will flip it if I go to speed 2 and put some pressure on it. Turned off the TV and everything other than my notebook which is just on and plugged in. Next time may try unplug that and see if it goes off. Oh well...:doh:
You may have an issue with your circuit or maybe the breaker is old. I have a dedicated 15A circuit I use in my shop and even on sticky paint with a soft pad ( can you say drag ) I can get the Flex to overheat and turn off without popping the breaker.
Hmmm, thinking that as it is a apartment that college students are in that breaker has gone a few too many time and may be "weak". I will see if maintenance can come out and change it out or run a 12 gauge extension cord from the outside GFI outlet to my window (right outside my window) and see if it pops.
I've got a good fat cable going into my garage, so no issues there, but when I plug in my electric mower in the front of the house, it'll trip the breaker in the third bedroom!