On Tue, 1 Oct 2013 19:06:20 -0700, "bob"
wrote:

If I set up an exhaust fan in the crawlspace that runs non stop, eventually
the motor would wear out and fail.
Would it go up in flame? Or are all motors used in the usa required to
shutdown gracefully?

Alot of fans/motors are used in commercial applications. I can't imagine
them going up in flames at the end of their lives.

The motor in a swamp-cooler of mine quietly stopped in the
middle of the night a few years back. I woke up and
happened to notice that it wasn't running, and went to
investigate. Thick, dark smoke was roiling from the
swamp-cooler. I immediately unplugged it and went back out
to take the shrouds off. I got the hose and started
squirting the motor down, but it took about 15 minutes
before it stopped spitting and steaming.

This cooler was on a 1950s 15a circuit shared with other
outlets and lighting. The breaker didn't pop.

I don't leave swamp-coolers on overnite anymore!

--
croy