[fox46]

I believe your analysis is correct. Assuming that the pulse width is sufficiently long enough to over come rise time caused by the inductance/resistance of the motor, full power is being applied during the pulse. i.e. 12 volts * 86 amps=1032 watts. That power is being dissipated only 20% of the time so the average power is 213.6 watts over the full period of the PWM. This does not account for other losses. That amounts to a lot of heat over a two minute match. Please remember that the current is also heating the circuit breaker. Since the breaker is a heat sensitive device, it may trip well before the motor hits the fail point. As the breaker resets fairly quickly, that adds more to equation than simply the motor and the more a breaker resets, the hotter it becomes. Also if you are using a Jaguar, you may trigger a fault condition there due to high temperature or sustained high current which shuts the Jaguar down for 3.5 seconds.
Leav, to answer your other question, fans are allowed if they follow all the other electrical rules for wire and breakers.

Thanks Al. Good call on the circuit breakers. When I was reading up on chopper style speed controls last night the inductance/resistance of the motor was where things started to get messy, differential equations began popping up and my desire to keep reading was all of a sudden non-existent lol. I don't believe the rise/fall time would have a significant effect on current consumption but its definitely a factor, especially at low power settings when the chopping frequency is high.