What happens when an attic exhaust fan fails?

My roof fan failed and it just stopped working. My neighbors failed and it set fire to his roof. This was about 1 am and if it were not for our neighbor across the street coming home late and seeing the flames, who knows. When I got new roof shingles, I put in passive ventilation. Frank

Mine failed and I unplugged it, but there is little chance of it starting a fire as it is well away from any combustible material.

The wiring is another matter, so I will have my new one on a surge protector with a circuit breaker.

Surge protectors protect electronics from spikes, but is there any spike so big it can cause fires in a motor?

Yep.

It is exactly this risk of fire that the only active attic vent I would consider is one of those little self-contained solar powered units. That and the wired ones suck a lot of juice, possibly more than you'd save on your A/C bill.

The motor should not be creating EMI. If was creating radio interference typically because it was failing. Maybe something as simple as worn brushes. Maybe arcing on a loose wire. Or maybe a hall effective sensor was not properly positioned.

No one can say if it is a fire hazard. But EMI was a precursor to fan failure.

Only person who can answer the OP's question with authority is one who opens that fan or who obtains a detailed autopsy report of that fan. Most would simply replace the defecive motor.

It might've been 8-10 years w/o EMI. Then about 10 yrs in the garage after the EMI started.

Methinks you are correct, kind sir. I turned the fan off yesterday.

I would if practical and cost-effective, as I need the garage air circ. and the window frame unit is built and functional. If I were able to find a bolt-up motor replacement at maybe Grainger, it'd likely cost twice the price of a new exhaust fan from a bigbox store?

Thx, Puddin'

"Mit der Dummheit kaempfen Goetter selbst vergebens!" -Friedrich Schiller

Isn't it called a necropsy when it's a fan? :)

Just out of curiosity, are you asking because you WANT to start a fire in your garage. If so, keep it running until something happens, If not, then a very, very small risk isn't work the possibility of it happening.